spvirit_codec/
spvd_decode.rs

1//! PVD (pvData) Type Introspection and Value Decoding
2//!
3//! Implements parsing of PVAccess field descriptions and value decoding
4//! according to the pvData serialization specification.
5
6use std::fmt;
7use tracing::debug;
8
9/// Re-export the free-standing `decode_string` from `epics_decode` for
10/// discoverability alongside the other decode helpers in this module.
11pub use crate::epics_decode::decode_string;
12
13/// PVD type codes from the specification
14#[repr(u8)]
15#[derive(Debug, Clone, Copy, PartialEq, Eq)]
16pub enum TypeCode {
17    Null = 0xFF,
18    Boolean = 0x00,
19    Int8 = 0x20,
20    Int16 = 0x21,
21    Int32 = 0x22,
22    Int64 = 0x23,
23    UInt8 = 0x24,
24    UInt16 = 0x25,
25    UInt32 = 0x26,
26    UInt64 = 0x27,
27    Float32 = 0x42,
28    Float64 = 0x43,
29    String = 0x60,
30    // Bounded string has 0x83 prefix followed by size
31    Variant = 0xFE, // Union with no fixed type (0xFF is Null)
32}
33
34impl TypeCode {
35    pub fn from_byte(b: u8) -> Option<Self> {
36        // Clear scalar-array mode bits (variable/bounded/fixed array)
37        let base = b & 0xE7;
38        match base {
39            0x00 => Some(TypeCode::Boolean),
40            0x20 => Some(TypeCode::Int8),
41            0x21 => Some(TypeCode::Int16),
42            0x22 => Some(TypeCode::Int32),
43            0x23 => Some(TypeCode::Int64),
44            0x24 => Some(TypeCode::UInt8),
45            0x25 => Some(TypeCode::UInt16),
46            0x26 => Some(TypeCode::UInt32),
47            0x27 => Some(TypeCode::UInt64),
48            0x42 => Some(TypeCode::Float32),
49            0x43 => Some(TypeCode::Float64),
50            0x60 => Some(TypeCode::String),
51            _ => None,
52        }
53    }
54
55    pub fn size(&self) -> Option<usize> {
56        match self {
57            TypeCode::Boolean | TypeCode::Int8 | TypeCode::UInt8 => Some(1),
58            TypeCode::Int16 | TypeCode::UInt16 => Some(2),
59            TypeCode::Int32 | TypeCode::UInt32 | TypeCode::Float32 => Some(4),
60            TypeCode::Int64 | TypeCode::UInt64 | TypeCode::Float64 => Some(8),
61            TypeCode::String | TypeCode::Null | TypeCode::Variant => None,
62        }
63    }
64}
65
66/// Field type description
67#[derive(Debug, Clone)]
68pub enum FieldType {
69    Scalar(TypeCode),
70    ScalarArray(TypeCode),
71    String,
72    StringArray,
73    Structure(StructureDesc),
74    StructureArray(StructureDesc),
75    Union(Vec<FieldDesc>),
76    UnionArray(Vec<FieldDesc>),
77    Variant,
78    VariantArray,
79    BoundedString(u32),
80}
81
82impl FieldType {
83    pub fn type_name(&self) -> &'static str {
84        match self {
85            FieldType::Scalar(tc) => match tc {
86                TypeCode::Boolean => "boolean",
87                TypeCode::Int8 => "byte",
88                TypeCode::Int16 => "short",
89                TypeCode::Int32 => "int",
90                TypeCode::Int64 => "long",
91                TypeCode::UInt8 => "ubyte",
92                TypeCode::UInt16 => "ushort",
93                TypeCode::UInt32 => "uint",
94                TypeCode::UInt64 => "ulong",
95                TypeCode::Float32 => "float",
96                TypeCode::Float64 => "double",
97                TypeCode::String => "string",
98                _ => "unknown",
99            },
100            FieldType::ScalarArray(tc) => match tc {
101                TypeCode::Float64 => "double[]",
102                TypeCode::Float32 => "float[]",
103                TypeCode::Int64 => "long[]",
104                TypeCode::Int32 => "int[]",
105                _ => "array",
106            },
107            FieldType::String => "string",
108            FieldType::StringArray => "string[]",
109            FieldType::Structure(_) => "structure",
110            FieldType::StructureArray(_) => "structure[]",
111            FieldType::Union(_) => "union",
112            FieldType::UnionArray(_) => "union[]",
113            FieldType::Variant => "any",
114            FieldType::VariantArray => "any[]",
115            FieldType::BoundedString(_) => "string",
116        }
117    }
118}
119
120/// Field description (name + type)
121#[derive(Debug, Clone)]
122pub struct FieldDesc {
123    pub name: String,
124    pub field_type: FieldType,
125}
126
127/// Structure description with optional ID
128#[derive(Debug, Clone)]
129pub struct StructureDesc {
130    pub struct_id: Option<String>,
131    pub fields: Vec<FieldDesc>,
132}
133
134impl StructureDesc {
135    pub fn new() -> Self {
136        Self {
137            struct_id: None,
138            fields: Vec::new(),
139        }
140    }
141
142    /// Look up a field by name.
143    pub fn field(&self, name: &str) -> Option<&FieldDesc> {
144        self.fields.iter().find(|f| f.name == name)
145    }
146}
147
148impl Default for StructureDesc {
149    fn default() -> Self {
150        Self::new()
151    }
152}
153
154impl fmt::Display for StructureDesc {
155    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
156        fn write_indent(f: &mut fmt::Formatter<'_>, depth: usize) -> fmt::Result {
157            for _ in 0..depth {
158                write!(f, "    ")?;
159            }
160            Ok(())
161        }
162
163        fn write_field_type(
164            f: &mut fmt::Formatter<'_>,
165            ft: &FieldType,
166            depth: usize,
167        ) -> fmt::Result {
168            match ft {
169                FieldType::Structure(desc) => write_structure(f, desc, depth),
170                FieldType::StructureArray(desc) => {
171                    write_structure(f, desc, depth)?;
172                    write!(f, "[]")
173                }
174                FieldType::Union(fields) => {
175                    writeln!(f, "union")?;
176                    for field in fields {
177                        write_indent(f, depth + 1)?;
178                        write!(f, "{} ", field.name)?;
179                        write_field_type(f, &field.field_type, depth + 1)?;
180                        writeln!(f)?;
181                    }
182                    Ok(())
183                }
184                FieldType::UnionArray(fields) => {
185                    writeln!(f, "union[]")?;
186                    for field in fields {
187                        write_indent(f, depth + 1)?;
188                        write!(f, "{} ", field.name)?;
189                        write_field_type(f, &field.field_type, depth + 1)?;
190                        writeln!(f)?;
191                    }
192                    Ok(())
193                }
194                other => write!(f, "{}", other.type_name()),
195            }
196        }
197
198        fn write_structure(
199            f: &mut fmt::Formatter<'_>,
200            desc: &StructureDesc,
201            depth: usize,
202        ) -> fmt::Result {
203            if let Some(id) = &desc.struct_id {
204                write!(f, "structure «{}»", id)?;
205            } else {
206                write!(f, "structure")?;
207            }
208            if desc.fields.is_empty() {
209                return Ok(());
210            }
211            writeln!(f)?;
212            for field in &desc.fields {
213                write_indent(f, depth + 1)?;
214                write!(f, "{} ", field.name)?;
215                write_field_type(f, &field.field_type, depth + 1)?;
216                writeln!(f)?;
217            }
218            Ok(())
219        }
220
221        write_structure(f, self, 0)
222    }
223}
224
225/// Decoded value
226#[derive(Debug, Clone)]
227pub enum DecodedValue {
228    Null,
229    Boolean(bool),
230    Int8(i8),
231    Int16(i16),
232    Int32(i32),
233    Int64(i64),
234    UInt8(u8),
235    UInt16(u16),
236    UInt32(u32),
237    UInt64(u64),
238    Float32(f32),
239    Float64(f64),
240    String(String),
241    Array(Vec<DecodedValue>),
242    Structure(Vec<(String, DecodedValue)>),
243    Raw(Vec<u8>),
244}
245
246impl fmt::Display for DecodedValue {
247    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
248        match self {
249            DecodedValue::Null => write!(f, "null"),
250            DecodedValue::Boolean(v) => write!(f, "{}", v),
251            DecodedValue::Int8(v) => write!(f, "{}", v),
252            DecodedValue::Int16(v) => write!(f, "{}", v),
253            DecodedValue::Int32(v) => write!(f, "{}", v),
254            DecodedValue::Int64(v) => write!(f, "{}", v),
255            DecodedValue::UInt8(v) => write!(f, "{}", v),
256            DecodedValue::UInt16(v) => write!(f, "{}", v),
257            DecodedValue::UInt32(v) => write!(f, "{}", v),
258            DecodedValue::UInt64(v) => write!(f, "{}", v),
259            DecodedValue::Float32(v) => write!(f, "{:.6}", v),
260            DecodedValue::Float64(v) => write!(f, "{:.6}", v),
261            DecodedValue::String(v) => write!(f, "\"{}\"", v),
262            DecodedValue::Array(arr) => {
263                write!(f, "[")?;
264                for (i, v) in arr.iter().enumerate() {
265                    if i > 0 {
266                        write!(f, ", ")?;
267                    }
268                    write!(f, "{}", v)?;
269                }
270                write!(f, "]")
271            }
272            DecodedValue::Structure(fields) => {
273                write!(f, "{{")?;
274                for (i, (name, val)) in fields.iter().enumerate() {
275                    if i > 0 {
276                        write!(f, ", ")?;
277                    }
278                    write!(f, "{}={}", name, val)?;
279                }
280                write!(f, "}}")
281            }
282            DecodedValue::Raw(data) => {
283                if data.len() <= 8 {
284                    write!(f, "<{} bytes: {}>", data.len(), hex::encode(data))
285                } else {
286                    write!(f, "<{} bytes>", data.len())
287                }
288            }
289        }
290    }
291}
292
293/// PVD Decoder state
294pub struct PvdDecoder {
295    is_be: bool,
296    /// IntrospectionRegistry: maps int16 keys to previously seen FieldTypes.
297    /// Populated when parsing `0xFD` (full-with-id) entries, looked up on `0xFE` (only-id).
298    registry: std::cell::RefCell<std::collections::HashMap<u16, FieldType>>,
299}
300
301impl PvdDecoder {
302    pub fn new(is_be: bool) -> Self {
303        Self {
304            is_be,
305            registry: std::cell::RefCell::new(std::collections::HashMap::new()),
306        }
307    }
308
309    /// Decode a size value (PVA variable-length encoding)
310    pub fn decode_size(&self, data: &[u8]) -> Option<(usize, usize)> {
311        if data.is_empty() {
312            return None;
313        }
314        let first = data[0];
315        if first == 0xFF {
316            // Special: -1 (null)
317            return Some((0, 1)); // Treat as 0 for simplicity
318        }
319        if first < 254 {
320            return Some((first as usize, 1));
321        }
322        if first == 254 {
323            // 4-byte size follows
324            if data.len() < 5 {
325                return None;
326            }
327            let size = if self.is_be {
328                u32::from_be_bytes([data[1], data[2], data[3], data[4]]) as usize
329            } else {
330                u32::from_le_bytes([data[1], data[2], data[3], data[4]]) as usize
331            };
332            return Some((size, 5));
333        }
334        // first == 255 is null marker, handled above.
335        None
336    }
337
338    /// Decode a string
339    pub fn decode_string(&self, data: &[u8]) -> Option<(String, usize)> {
340        let (size, size_bytes) = self.decode_size(data)?;
341        if size == 0 {
342            return Some((String::new(), size_bytes));
343        }
344        if data.len() < size_bytes + size {
345            return None;
346        }
347        let s = std::str::from_utf8(&data[size_bytes..size_bytes + size]).ok()?;
348        Some((s.to_string(), size_bytes + size))
349    }
350
351    /// Parse field description from introspection data
352    pub fn parse_field_desc(&self, data: &[u8]) -> Option<(FieldDesc, usize)> {
353        if data.is_empty() {
354            return None;
355        }
356
357        let mut offset = 0;
358
359        // Parse field name
360        let (name, consumed) = self.decode_string(&data[offset..])?;
361        offset += consumed;
362
363        if offset >= data.len() {
364            return None;
365        }
366
367        // Parse type descriptor
368        let (field_type, type_consumed) = self.parse_type_desc(&data[offset..])?;
369        offset += type_consumed;
370
371        Some((FieldDesc { name, field_type }, offset))
372    }
373
374    /// Parse type descriptor
375    fn parse_type_desc(&self, data: &[u8]) -> Option<(FieldType, usize)> {
376        if data.is_empty() {
377            return None;
378        }
379
380        let type_byte = data[0];
381        let mut offset = 1;
382
383        // Check for NULL type
384        if type_byte == 0xFF {
385            return Some((FieldType::Variant, 1));
386        }
387
388        // Full-with-id from IntrospectionRegistry:
389        // 0xFD + int16 key + type descriptor payload.
390        if type_byte == 0xFD {
391            if data.len() < 3 {
392                return None;
393            }
394            let key = if self.is_be {
395                u16::from_be_bytes([data[1], data[2]])
396            } else {
397                u16::from_le_bytes([data[1], data[2]])
398            };
399            if let Some((field_type, consumed)) = self.parse_type_desc(&data[3..]) {
400                self.registry.borrow_mut().insert(key, field_type.clone());
401                return Some((field_type, 3 + consumed));
402            }
403            return None;
404        }
405
406        // Only-id from IntrospectionRegistry:
407        // 0xFE + int16 key — reference to a previously seen type.
408        if type_byte == 0xFE {
409            if data.len() < 3 {
410                return None;
411            }
412            let key = if self.is_be {
413                u16::from_be_bytes([data[1], data[2]])
414            } else {
415                u16::from_le_bytes([data[1], data[2]])
416            };
417            if let Some(ft) = self.registry.borrow().get(&key) {
418                return Some((ft.clone(), 3));
419            }
420            debug!("Type descriptor ONLY_ID (0xFE) key={} not found in registry", key);
421            return None;
422        }
423
424        // Check for structure (0x80) or structure array (0x88)
425        if type_byte == 0x80 || type_byte == 0x88 {
426            let is_array = (type_byte & 0x08) != 0;
427            if is_array {
428                // Skip the inner structure element tag (0x80)
429                if offset >= data.len() || data[offset] != 0x80 {
430                    return None;
431                }
432                offset += 1;
433            }
434            let (struct_desc, consumed) = self.parse_structure_desc(&data[offset..])?;
435            offset += consumed;
436            if is_array {
437                return Some((FieldType::StructureArray(struct_desc), offset));
438            } else {
439                return Some((FieldType::Structure(struct_desc), offset));
440            }
441        }
442
443        // Check for union (0x81) or union array (0x89)
444        if type_byte == 0x81 || type_byte == 0x89 {
445            let is_array = (type_byte & 0x08) != 0;
446            if is_array {
447                // Skip the inner union element tag (0x81)
448                if offset >= data.len() || data[offset] != 0x81 {
449                    return None;
450                }
451                offset += 1;
452            }
453            // Parse union fields (same as structure)
454            let (struct_desc, consumed) = self.parse_structure_desc(&data[offset..])?;
455            offset += consumed;
456            if is_array {
457                return Some((FieldType::UnionArray(struct_desc.fields), offset));
458            } else {
459                return Some((FieldType::Union(struct_desc.fields), offset));
460            }
461        }
462
463        // Check for variant/any (0x82) or variant array (0x8A)
464        if type_byte == 0x82 {
465            return Some((FieldType::Variant, 1));
466        }
467        if type_byte == 0x8A {
468            return Some((FieldType::VariantArray, 1));
469        }
470
471        // Check for bounded string (0x83, legacy 0x86 accepted for compatibility)
472        if type_byte == 0x83 || type_byte == 0x86 {
473            let (bound, consumed) = self.decode_size(&data[offset..])?;
474            offset += consumed;
475            return Some((FieldType::BoundedString(bound as u32), offset));
476        }
477
478        // Scalar / scalar-array with mode bits:
479        // 0x00=not-array, 0x08=variable, 0x10=bounded, 0x18=fixed
480        let scalar_or_array = type_byte & 0x18;
481        let is_array = scalar_or_array != 0;
482        if is_array && scalar_or_array != 0x08 {
483            // Consume bounded/fixed max length for alignment, even if we don't model it.
484            let (_bound, consumed) = self.decode_size(&data[offset..])?;
485            offset += consumed;
486        }
487        let base_type = type_byte & 0xE7;
488
489        // String type
490        if base_type == 0x60 {
491            if is_array {
492                return Some((FieldType::StringArray, offset));
493            } else {
494                return Some((FieldType::String, offset));
495            }
496        }
497
498        // Numeric types
499        if let Some(tc) = TypeCode::from_byte(base_type) {
500            if is_array {
501                return Some((FieldType::ScalarArray(tc), offset));
502            } else {
503                return Some((FieldType::Scalar(tc), offset));
504            }
505        }
506
507        debug!("Unknown type byte: 0x{:02x}", type_byte);
508        None
509    }
510
511    /// Parse structure description
512    fn parse_structure_desc(&self, data: &[u8]) -> Option<(StructureDesc, usize)> {
513        let mut offset = 0;
514
515        // Parse optional struct ID
516        let (struct_id, consumed) = self.decode_string(&data[offset..])?;
517        offset += consumed;
518
519        let struct_id = if struct_id.is_empty() {
520            None
521        } else {
522            Some(struct_id)
523        };
524
525        // Parse field count
526        let (field_count, consumed) = self.decode_size(&data[offset..])?;
527        offset += consumed;
528
529        let mut fields = Vec::with_capacity(field_count);
530
531        for _ in 0..field_count {
532            if offset >= data.len() {
533                break;
534            }
535            if let Some((field, consumed)) = self.parse_field_desc(&data[offset..]) {
536                offset += consumed;
537                fields.push(field);
538            } else {
539                break;
540            }
541        }
542
543        Some((StructureDesc { struct_id, fields }, offset))
544    }
545
546    /// Parse the full type introspection from INIT response
547    pub fn parse_introspection(&self, data: &[u8]) -> Option<StructureDesc> {
548        self.parse_introspection_with_len(data)
549            .map(|(desc, _)| desc)
550    }
551
552    /// Parse full type introspection and return consumed bytes.
553    pub fn parse_introspection_with_len(&self, data: &[u8]) -> Option<(StructureDesc, usize)> {
554        if data.is_empty() {
555            return None;
556        }
557
558        // The introspection starts with a type byte
559        let type_byte = data[0];
560
561        // Should be a structure (0x80)
562        if type_byte == 0x80 {
563            let (desc, consumed) = self.parse_structure_desc(&data[1..])?;
564            return Some((desc, 1 + consumed));
565        }
566
567        // Full-with-id from IntrospectionRegistry:
568        // 0xFD + int16 key + field type descriptor payload.
569        if type_byte == 0xFD {
570            if data.len() < 3 {
571                return None;
572            }
573            let key = if self.is_be {
574                u16::from_be_bytes([data[1], data[2]])
575            } else {
576                u16::from_le_bytes([data[1], data[2]])
577            };
578            if let Some((desc, consumed)) = self.parse_introspection_with_len(&data[3..]) {
579                // Register this structure type for later 0xFE references
580                if !desc.fields.is_empty() {
581                    self.registry.borrow_mut().insert(
582                        key,
583                        FieldType::Structure(desc.clone()),
584                    );
585                } else {
586                    self.registry.borrow_mut().insert(
587                        key,
588                        FieldType::Structure(desc.clone()),
589                    );
590                }
591                return Some((desc, 3 + consumed));
592            }
593            return None;
594        }
595
596        // Only-id from IntrospectionRegistry:
597        // 0xFE + int16 key — reference to a previously seen type.
598        if type_byte == 0xFE {
599            if data.len() < 3 {
600                return None;
601            }
602            let key = if self.is_be {
603                u16::from_be_bytes([data[1], data[2]])
604            } else {
605                u16::from_le_bytes([data[1], data[2]])
606            };
607            if let Some(ft) = self.registry.borrow().get(&key) {
608                if let FieldType::Structure(desc) = ft {
609                    return Some((desc.clone(), 3));
610                }
611            }
612            debug!("Introspection ONLY_ID (0xFE) key={} not found in registry", key);
613            return None;
614        }
615
616        debug!("Unexpected introspection type byte: 0x{:02x}", type_byte);
617        None
618    }
619
620    /// Decode a scalar value
621    fn decode_scalar(&self, data: &[u8], tc: TypeCode) -> Option<(DecodedValue, usize)> {
622        let size = tc.size()?;
623        if data.len() < size {
624            return None;
625        }
626
627        let value = match tc {
628            TypeCode::Boolean => DecodedValue::Boolean(data[0] != 0),
629            TypeCode::Int8 => DecodedValue::Int8(data[0] as i8),
630            TypeCode::UInt8 => DecodedValue::UInt8(data[0]),
631            TypeCode::Int16 => {
632                let v = if self.is_be {
633                    i16::from_be_bytes([data[0], data[1]])
634                } else {
635                    i16::from_le_bytes([data[0], data[1]])
636                };
637                DecodedValue::Int16(v)
638            }
639            TypeCode::UInt16 => {
640                let v = if self.is_be {
641                    u16::from_be_bytes([data[0], data[1]])
642                } else {
643                    u16::from_le_bytes([data[0], data[1]])
644                };
645                DecodedValue::UInt16(v)
646            }
647            TypeCode::Int32 => {
648                let v = if self.is_be {
649                    i32::from_be_bytes(data[0..4].try_into().unwrap())
650                } else {
651                    i32::from_le_bytes(data[0..4].try_into().unwrap())
652                };
653                DecodedValue::Int32(v)
654            }
655            TypeCode::UInt32 => {
656                let v = if self.is_be {
657                    u32::from_be_bytes(data[0..4].try_into().unwrap())
658                } else {
659                    u32::from_le_bytes(data[0..4].try_into().unwrap())
660                };
661                DecodedValue::UInt32(v)
662            }
663            TypeCode::Int64 => {
664                let v = if self.is_be {
665                    i64::from_be_bytes(data[0..8].try_into().unwrap())
666                } else {
667                    i64::from_le_bytes(data[0..8].try_into().unwrap())
668                };
669                DecodedValue::Int64(v)
670            }
671            TypeCode::UInt64 => {
672                let v = if self.is_be {
673                    u64::from_be_bytes(data[0..8].try_into().unwrap())
674                } else {
675                    u64::from_le_bytes(data[0..8].try_into().unwrap())
676                };
677                DecodedValue::UInt64(v)
678            }
679            TypeCode::Float32 => {
680                let v = if self.is_be {
681                    f32::from_be_bytes(data[0..4].try_into().unwrap())
682                } else {
683                    f32::from_le_bytes(data[0..4].try_into().unwrap())
684                };
685                DecodedValue::Float32(v)
686            }
687            TypeCode::Float64 => {
688                let v = if self.is_be {
689                    f64::from_be_bytes(data[0..8].try_into().unwrap())
690                } else {
691                    f64::from_le_bytes(data[0..8].try_into().unwrap())
692                };
693                DecodedValue::Float64(v)
694            }
695            _ => return None,
696        };
697
698        Some((value, size))
699    }
700
701    /// Decode value according to field type
702    pub fn decode_value(
703        &self,
704        data: &[u8],
705        field_type: &FieldType,
706    ) -> Option<(DecodedValue, usize)> {
707        match field_type {
708            FieldType::Scalar(tc) => self.decode_scalar(data, *tc),
709            FieldType::String | FieldType::BoundedString(_) => {
710                let (s, consumed) = self.decode_string(data)?;
711                Some((DecodedValue::String(s), consumed))
712            }
713            FieldType::ScalarArray(tc) => {
714                let (count, size_consumed) = self.decode_size(data)?;
715                let mut offset = size_consumed;
716                let limit = count.min(4_000_000);
717                let mut values = Vec::with_capacity(limit);
718                let elem_size = tc.size().unwrap_or(1);
719                for _ in 0..limit {
720                    if let Some((val, consumed)) = self.decode_scalar(&data[offset..], *tc) {
721                        values.push(val);
722                        offset += consumed;
723                    } else {
724                        break;
725                    }
726                }
727                // Skip past any remaining elements we didn't store, so the
728                // stream stays aligned for the next field.
729                let remaining = count.saturating_sub(limit);
730                offset += remaining * elem_size;
731                Some((DecodedValue::Array(values), offset))
732            }
733            FieldType::StringArray => {
734                let (count, size_consumed) = self.decode_size(data)?;
735                let mut offset = size_consumed;
736                let max_items = count.min(4096);
737                let mut values = Vec::with_capacity(max_items);
738                for _ in 0..max_items {
739                    if let Some((s, consumed)) = self.decode_string(&data[offset..]) {
740                        values.push(DecodedValue::String(s));
741                        offset += consumed;
742                    } else {
743                        break;
744                    }
745                }
746                Some((DecodedValue::Array(values), offset))
747            }
748            FieldType::Structure(desc) => self.decode_structure(data, desc),
749            FieldType::StructureArray(desc) => {
750                let (count, size_consumed) = self.decode_size(data)?;
751                let mut offset = size_consumed;
752                let mut values = Vec::with_capacity(count.min(256));
753                for _ in 0..count.min(256) {
754                    // Read per-element null indicator (0 = null, non-zero = present)
755                    if offset >= data.len() {
756                        return None;
757                    }
758                    let null_indicator = data[offset];
759                    offset += 1;
760                    if null_indicator == 0 {
761                        // null element – push empty structure placeholder
762                        values.push(DecodedValue::Structure(Vec::new()));
763                        continue;
764                    }
765                    let (item, consumed) = self.decode_structure(&data[offset..], desc)?;
766                    values.push(item);
767                    offset += consumed;
768                }
769                Some((DecodedValue::Array(values), offset))
770            }
771            FieldType::Union(fields) => {
772                let (selector, consumed) = self.decode_size(data)?;
773                let field = fields.get(selector)?;
774                let (value, val_consumed) =
775                    self.decode_value(&data[consumed..], &field.field_type)?;
776                Some((
777                    DecodedValue::Structure(vec![(field.name.clone(), value)]),
778                    consumed + val_consumed,
779                ))
780            }
781            FieldType::UnionArray(fields) => {
782                let (count, size_consumed) = self.decode_size(data)?;
783                let mut offset = size_consumed;
784                let mut values = Vec::with_capacity(count.min(128));
785                for _ in 0..count.min(128) {
786                    let (selector, consumed) = self.decode_size(&data[offset..])?;
787                    offset += consumed;
788                    let field = fields.get(selector)?;
789                    let (value, val_consumed) =
790                        self.decode_value(&data[offset..], &field.field_type)?;
791                    offset += val_consumed;
792                    values.push(DecodedValue::Structure(vec![(field.name.clone(), value)]));
793                }
794                Some((DecodedValue::Array(values), offset))
795            }
796            FieldType::Variant => {
797                if data.is_empty() {
798                    return None;
799                }
800                if data[0] == 0xFF {
801                    return Some((DecodedValue::Null, 1));
802                }
803                let (variant_type, type_consumed) = self.parse_type_desc(data)?;
804                let (variant_value, value_consumed) =
805                    self.decode_value(&data[type_consumed..], &variant_type)?;
806                Some((variant_value, type_consumed + value_consumed))
807            }
808            FieldType::VariantArray => {
809                let (count, size_consumed) = self.decode_size(data)?;
810                let mut offset = size_consumed;
811                let mut values = Vec::with_capacity(count.min(128));
812                for _ in 0..count.min(128) {
813                    let (v, consumed) = self.decode_value(&data[offset..], &FieldType::Variant)?;
814                    values.push(v);
815                    offset += consumed;
816                }
817                Some((DecodedValue::Array(values), offset))
818            }
819        }
820    }
821
822    /// Decode a structure value using the field descriptions
823    pub fn decode_structure(
824        &self,
825        data: &[u8],
826        desc: &StructureDesc,
827    ) -> Option<(DecodedValue, usize)> {
828        let mut offset = 0;
829        let mut fields: Vec<(String, DecodedValue)> = Vec::new();
830
831        for field in &desc.fields {
832            if offset >= data.len() {
833                break;
834            }
835            if let Some((value, consumed)) = self.decode_value(&data[offset..], &field.field_type) {
836                fields.push((field.name.clone(), value));
837                offset += consumed;
838            } else {
839                // Can't decode this field, stop
840                break;
841            }
842        }
843
844        Some((DecodedValue::Structure(fields), offset))
845    }
846
847    /// Decode a structure with a bitset indicating which fields are present
848    /// This is used for delta updates in MONITOR
849    pub fn decode_structure_with_bitset(
850        &self,
851        data: &[u8],
852        desc: &StructureDesc,
853    ) -> Option<(DecodedValue, usize)> {
854        if data.is_empty() {
855            return None;
856        }
857
858        let mut offset = 0;
859
860        // Parse the bitset - PVA uses size-encoded bitset
861        let (bitset_size, size_consumed) = self.decode_size(data)?;
862        offset += size_consumed;
863
864        if bitset_size == 0 || offset + bitset_size > data.len() {
865            return Some((DecodedValue::Structure(vec![]), offset));
866        }
867
868        let bitset = &data[offset..offset + bitset_size];
869        offset += bitset_size;
870
871        let (value, consumed) =
872            self.decode_structure_with_bitset_body(&data[offset..], desc, bitset)?;
873        Some((value, offset + consumed))
874    }
875
876    /// Decode a structure with changed and overrun bitsets (MONITOR updates)
877    pub fn decode_structure_with_bitset_and_overrun(
878        &self,
879        data: &[u8],
880        desc: &StructureDesc,
881    ) -> Option<(DecodedValue, usize)> {
882        if data.is_empty() {
883            return None;
884        }
885        let mut offset = 0usize;
886        let (changed_size, consumed1) = self.decode_size(&data[offset..])?;
887        offset += consumed1;
888        if offset + changed_size > data.len() {
889            return None;
890        }
891        let changed = &data[offset..offset + changed_size];
892        offset += changed_size;
893
894        let (overrun_size, consumed2) = self.decode_size(&data[offset..])?;
895        offset += consumed2;
896        if offset + overrun_size > data.len() {
897            return None;
898        }
899        offset += overrun_size;
900
901        let (value, consumed) =
902            self.decode_structure_with_bitset_body(&data[offset..], desc, changed)?;
903        Some((value, offset + consumed))
904    }
905
906    /// Decode a structure with changed bitset, data, then overrun bitset (spec order)
907    pub fn decode_structure_with_bitset_then_overrun(
908        &self,
909        data: &[u8],
910        desc: &StructureDesc,
911    ) -> Option<(DecodedValue, usize)> {
912        if data.is_empty() {
913            return None;
914        }
915        let mut offset = 0usize;
916        let (changed_size, consumed1) = self.decode_size(&data[offset..])?;
917        offset += consumed1;
918        if offset + changed_size > data.len() {
919            return None;
920        }
921        let changed = &data[offset..offset + changed_size];
922        offset += changed_size;
923
924        let (value, consumed) =
925            self.decode_structure_with_bitset_body(&data[offset..], desc, changed)?;
926        offset += consumed;
927
928        let (overrun_size, consumed2) = self.decode_size(&data[offset..])?;
929        offset += consumed2;
930        if offset + overrun_size > data.len() {
931            return None;
932        }
933        offset += overrun_size;
934
935        Some((value, offset))
936    }
937
938    fn decode_structure_with_bitset_body(
939        &self,
940        data: &[u8],
941        desc: &StructureDesc,
942        bitset: &[u8],
943    ) -> Option<(DecodedValue, usize)> {
944        // Bit 0 is for the whole structure, field bits start at bit 1
945        debug!(
946            "Bitset: {:02x?} (size={}), total_fields={}",
947            bitset,
948            bitset.len(),
949            count_structure_fields(desc)
950        );
951        debug!(
952            "Structure fields: {:?}",
953            desc.fields.iter().map(|f| &f.name).collect::<Vec<_>>()
954        );
955
956        // Special case: bitset contains only bit0 (whole structure) and no field bits.
957        let mut has_field_bits = false;
958        if !bitset.is_empty() {
959            for (i, b) in bitset.iter().enumerate() {
960                let mask = if i == 0 { *b & !0x01 } else { *b };
961                if mask != 0 {
962                    has_field_bits = true;
963                    break;
964                }
965            }
966        }
967        if !has_field_bits && !bitset.is_empty() && (bitset[0] & 0x01) != 0 {
968            if let Some((value, consumed)) = self.decode_structure(data, desc) {
969                return Some((value, consumed));
970            }
971        }
972
973        let mut fields: Vec<(String, DecodedValue)> = Vec::new();
974        let mut offset = 0usize;
975
976        fn decode_with_bitset_recursive(
977            decoder: &PvdDecoder,
978            data: &[u8],
979            offset: &mut usize,
980            desc: &StructureDesc,
981            bitset: &[u8],
982            bit_offset: &mut usize,
983            fields: &mut Vec<(String, DecodedValue)>,
984        ) -> bool {
985            for field in &desc.fields {
986                let byte_idx = *bit_offset / 8;
987                let bit_idx = *bit_offset % 8;
988                let current_bit = *bit_offset;
989                *bit_offset += 1;
990
991                let field_present = if byte_idx < bitset.len() {
992                    (bitset[byte_idx] & (1 << bit_idx)) != 0
993                } else {
994                    false
995                };
996
997                debug!(
998                    "Field '{}' at bit {}: present={}",
999                    field.name, current_bit, field_present
1000                );
1001
1002                if let FieldType::Structure(nested_desc) = &field.field_type {
1003                    let child_start_bit = *bit_offset;
1004                    let child_field_count = count_structure_fields(nested_desc);
1005
1006                    let mut any_child_bits_set = false;
1007                    for i in 0..child_field_count {
1008                        let check_byte = (child_start_bit + i) / 8;
1009                        let check_bit = (child_start_bit + i) % 8;
1010                        if check_byte < bitset.len() && (bitset[check_byte] & (1 << check_bit)) != 0
1011                        {
1012                            any_child_bits_set = true;
1013                            break;
1014                        }
1015                    }
1016
1017                    debug!(
1018                        "Nested structure '{}': parent_present={}, child_start_bit={}, child_count={}, any_child_bits_set={}",
1019                        field.name,
1020                        field_present,
1021                        child_start_bit,
1022                        child_field_count,
1023                        any_child_bits_set
1024                    );
1025
1026                    if field_present && !any_child_bits_set {
1027                        *bit_offset += child_field_count;
1028                        if *offset < data.len() {
1029                            if let Some((value, consumed)) =
1030                                decoder.decode_structure(&data[*offset..], nested_desc)
1031                            {
1032                                debug!(
1033                                    "Decoded full nested structure '{}', consumed {} bytes",
1034                                    field.name, consumed
1035                                );
1036                                fields.push((field.name.clone(), value));
1037                                *offset += consumed;
1038                            } else {
1039                                debug!("Failed to decode full nested structure '{}'", field.name);
1040                                return false;
1041                            }
1042                        }
1043                    } else if any_child_bits_set {
1044                        let mut nested_fields: Vec<(String, DecodedValue)> = Vec::new();
1045                        if !decode_with_bitset_recursive(
1046                            decoder,
1047                            data,
1048                            offset,
1049                            nested_desc,
1050                            bitset,
1051                            bit_offset,
1052                            &mut nested_fields,
1053                        ) {
1054                            return false;
1055                        }
1056                        debug!(
1057                            "Nested structure '{}' decoded {} fields",
1058                            field.name,
1059                            nested_fields.len()
1060                        );
1061                        if !nested_fields.is_empty() {
1062                            fields
1063                                .push((field.name.clone(), DecodedValue::Structure(nested_fields)));
1064                        }
1065                    } else {
1066                        *bit_offset += child_field_count;
1067                    }
1068                } else if field_present {
1069                    if *offset >= data.len() {
1070                        debug!(
1071                            "Data exhausted at offset {} for field '{}'",
1072                            *offset, field.name
1073                        );
1074                        return false;
1075                    }
1076                    if let Some((value, consumed)) =
1077                        decoder.decode_value(&data[*offset..], &field.field_type)
1078                    {
1079                        fields.push((field.name.clone(), value));
1080                        *offset += consumed;
1081                    } else {
1082                        return false;
1083                    }
1084                }
1085            }
1086            true
1087        }
1088
1089        let mut bit_offset = 1;
1090        decode_with_bitset_recursive(
1091            self,
1092            data,
1093            &mut offset,
1094            desc,
1095            bitset,
1096            &mut bit_offset,
1097            &mut fields,
1098        );
1099        Some((DecodedValue::Structure(fields), offset))
1100    }
1101}
1102
1103/// Count total fields in a structure (including nested)
1104fn count_structure_fields(desc: &StructureDesc) -> usize {
1105    let mut count = 0;
1106    for field in &desc.fields {
1107        count += 1;
1108        if let FieldType::Structure(nested) = &field.field_type {
1109            count += count_structure_fields(nested);
1110        }
1111    }
1112    count
1113}
1114
1115/// Extract a sub-field from a StructureDesc by dot-separated path.
1116/// Returns the sub-field as an owned StructureDesc. For leaf (non-structure)
1117/// fields, returns a single-field StructureDesc wrapping the matched field.
1118/// Returns the full desc if path is empty.
1119pub fn extract_subfield_desc(desc: &StructureDesc, path: &str) -> Option<StructureDesc> {
1120    if path.is_empty() {
1121        return Some(desc.clone());
1122    }
1123    let mut parts = path.splitn(2, '.');
1124    let head = parts.next()?;
1125    let tail = parts.next().unwrap_or("");
1126    for field in &desc.fields {
1127        if field.name == head {
1128            match &field.field_type {
1129                FieldType::Structure(nested) | FieldType::StructureArray(nested) => {
1130                    return extract_subfield_desc(nested, tail);
1131                }
1132                _ => {
1133                    if tail.is_empty() {
1134                        return Some(StructureDesc {
1135                            struct_id: None,
1136                            fields: vec![field.clone()],
1137                        });
1138                    }
1139                    return None;
1140                }
1141            }
1142        }
1143    }
1144    None
1145}
1146
1147/// Format a structure description for display
1148pub fn format_structure_desc(desc: &StructureDesc) -> String {
1149    let mut parts = Vec::new();
1150    if let Some(ref id) = desc.struct_id {
1151        parts.push(id.clone());
1152    }
1153    for field in &desc.fields {
1154        parts.push(format!("{}:{}", field.name, field.field_type.type_name()));
1155    }
1156    parts.join(", ")
1157}
1158
1159pub fn format_structure_tree(desc: &StructureDesc) -> String {
1160    fn push_fields(out: &mut Vec<String>, fields: &[FieldDesc], indent: usize) {
1161        let prefix = "  ".repeat(indent);
1162        for field in fields {
1163            match &field.field_type {
1164                FieldType::Structure(nested) => {
1165                    out.push(format!("{}{}: structure", prefix, field.name));
1166                    push_fields(out, &nested.fields, indent + 1);
1167                }
1168                FieldType::StructureArray(nested) => {
1169                    out.push(format!("{}{}: structure[]", prefix, field.name));
1170                    push_fields(out, &nested.fields, indent + 1);
1171                }
1172                FieldType::Union(variants) => {
1173                    out.push(format!("{}{}: union", prefix, field.name));
1174                    push_fields(out, variants, indent + 1);
1175                }
1176                FieldType::UnionArray(variants) => {
1177                    out.push(format!("{}{}: union[]", prefix, field.name));
1178                    push_fields(out, variants, indent + 1);
1179                }
1180                FieldType::BoundedString(bound) => {
1181                    out.push(format!("{}{}: string<={}", prefix, field.name, bound));
1182                }
1183                _ => {
1184                    out.push(format!(
1185                        "{}{}: {}",
1186                        prefix,
1187                        field.name,
1188                        field.field_type.type_name()
1189                    ));
1190                }
1191            }
1192        }
1193    }
1194
1195    let mut lines = Vec::new();
1196    if let Some(id) = &desc.struct_id {
1197        lines.push(format!("struct {}", id));
1198    } else {
1199        lines.push("struct <anonymous>".to_string());
1200    }
1201    push_fields(&mut lines, &desc.fields, 0);
1202    lines.join("\n")
1203}
1204
1205/// Extract the "value" field from a decoded NTScalar structure
1206pub fn extract_nt_scalar_value(decoded: &DecodedValue) -> Option<&DecodedValue> {
1207    if let DecodedValue::Structure(fields) = decoded {
1208        for (name, value) in fields {
1209            if name == "value" {
1210                return Some(value);
1211            }
1212        }
1213    }
1214    None
1215}
1216
1217/// Compact display of decoded value for logging - shows only updated fields concisely
1218pub fn format_compact_value(decoded: &DecodedValue) -> String {
1219    match decoded {
1220        DecodedValue::Structure(fields) => {
1221            if fields.is_empty() {
1222                return "{}".to_string();
1223            }
1224
1225            let mut parts = Vec::new();
1226
1227            for (name, val) in fields {
1228                let formatted = format_field_value_compact(name, val);
1229                if !formatted.is_empty() {
1230                    parts.push(formatted);
1231                }
1232            }
1233
1234            parts.join(", ")
1235        }
1236        _ => format!("{}", decoded),
1237    }
1238}
1239
1240/// Format a single field value compactly - shows key info for known structures
1241fn format_field_value_compact(name: &str, val: &DecodedValue) -> String {
1242    match val {
1243        DecodedValue::Structure(fields) => {
1244            // For known EPICS NTScalar structures, show only key fields
1245            match name {
1246                "alarm" => {
1247                    // Show severity and message if non-zero/non-empty
1248                    let severity = fields.iter().find(|(n, _)| n == "severity");
1249                    let message = fields.iter().find(|(n, _)| n == "message");
1250                    let mut parts = Vec::new();
1251                    if let Some((_, DecodedValue::Int32(s))) = severity {
1252                        if *s != 0 {
1253                            parts.push(format!("sev={}", s));
1254                        }
1255                    }
1256                    if let Some((_, DecodedValue::String(m))) = message {
1257                        if !m.is_empty() {
1258                            parts.push(format!("\"{}\"", m));
1259                        }
1260                    }
1261                    if parts.is_empty() {
1262                        String::new() // Don't show alarm if it's OK
1263                    } else {
1264                        format!("alarm={{{}}}", parts.join(", "))
1265                    }
1266                }
1267                "timeStamp" => {
1268                    // Show just seconds or skip entirely for brevity
1269                    let secs = fields.iter().find(|(n, _)| n == "secondsPastEpoch");
1270                    if let Some((_, DecodedValue::Int64(s))) = secs {
1271                        format!("ts={}", s)
1272                    } else {
1273                        String::new()
1274                    }
1275                }
1276                "display" | "control" | "valueAlarm" => {
1277                    // Skip verbose metadata structures in compact view
1278                    String::new()
1279                }
1280                _ => {
1281                    // For other structures, show all fields
1282                    let nested: Vec<String> = fields
1283                        .iter()
1284                        .map(|(n, v)| format!("{}={}", n, format_scalar_value(v)))
1285                        .collect();
1286
1287                    if nested.is_empty() {
1288                        String::new()
1289                    } else {
1290                        format!("{}={{{}}}", name, nested.join(", "))
1291                    }
1292                }
1293            }
1294        }
1295        _ => {
1296            format!("{}={}", name, format_scalar_value(val))
1297        }
1298    }
1299}
1300
1301/// Format a scalar value concisely
1302fn format_scalar_value(val: &DecodedValue) -> String {
1303    match val {
1304        DecodedValue::Null => "null".to_string(),
1305        DecodedValue::Boolean(v) => format!("{}", v),
1306        DecodedValue::Int8(v) => format!("{}", v),
1307        DecodedValue::Int16(v) => format!("{}", v),
1308        DecodedValue::Int32(v) => format!("{}", v),
1309        DecodedValue::Int64(v) => format!("{}", v),
1310        DecodedValue::UInt8(v) => format!("{}", v),
1311        DecodedValue::UInt16(v) => format!("{}", v),
1312        DecodedValue::UInt32(v) => format!("{}", v),
1313        DecodedValue::UInt64(v) => format!("{}", v),
1314        DecodedValue::Float32(v) => format!("{:.4}", v),
1315        DecodedValue::Float64(v) => format!("{:.6}", v),
1316        DecodedValue::String(v) => format!("\"{}\"", v),
1317        DecodedValue::Array(arr) => {
1318            if arr.is_empty() {
1319                "[]".to_string()
1320            } else {
1321                let items: Vec<String> = arr.iter().map(|v| format_scalar_value(v)).collect();
1322                format!("[{}]", items.join(", "))
1323            }
1324        }
1325        DecodedValue::Structure(fields) => {
1326            let nested: Vec<String> = fields
1327                .iter()
1328                .map(|(n, v)| format!("{}={}", n, format_scalar_value(v)))
1329                .collect();
1330            format!("{{{}}}", nested.join(", "))
1331        }
1332        DecodedValue::Raw(data) => {
1333            if data.len() <= 4 {
1334                format!("<{}>", hex::encode(data))
1335            } else {
1336                format!("<{}B>", data.len())
1337            }
1338        }
1339    }
1340}
1341
1342#[cfg(test)]
1343mod tests {
1344    use super::*;
1345
1346    #[test]
1347    fn test_decode_size() {
1348        let decoder = PvdDecoder::new(false);
1349
1350        // Small size (single byte)
1351        assert_eq!(decoder.decode_size(&[5]), Some((5, 1)));
1352        assert_eq!(decoder.decode_size(&[253]), Some((253, 1)));
1353
1354        // Medium/large size (5 bytes, 254 prefix + uint32)
1355        assert_eq!(
1356            decoder.decode_size(&[254, 0x00, 0x01, 0x00, 0x00]),
1357            Some((256, 5))
1358        );
1359    }
1360
1361    #[test]
1362    fn test_parse_introspection_full_with_id() {
1363        let decoder = PvdDecoder::new(false);
1364        let data = vec![
1365            0xFD, // FULL_WITH_ID
1366            0x06, 0x00, // registry key (little-endian)
1367            0x80, // structure type follows
1368            0x00, // empty struct id
1369            0x01, // one field
1370            0x05, b'v', b'a', b'l', b'u', b'e', // field name
1371            0x43, // float64
1372        ];
1373        let desc = decoder
1374            .parse_introspection(&data)
1375            .expect("parsed introspection");
1376        assert_eq!(desc.fields.len(), 1);
1377        assert_eq!(desc.fields[0].name, "value");
1378        match desc.fields[0].field_type {
1379            FieldType::Scalar(TypeCode::Float64) => {}
1380            _ => panic!("expected float64 value field"),
1381        }
1382    }
1383
1384    #[test]
1385    fn test_decode_string() {
1386        let decoder = PvdDecoder::new(false);
1387
1388        // Empty string
1389        assert_eq!(decoder.decode_string(&[0]), Some((String::new(), 1)));
1390
1391        // "hello"
1392        let data = [5, b'h', b'e', b'l', b'l', b'o'];
1393        assert_eq!(decoder.decode_string(&data), Some(("hello".to_string(), 6)));
1394    }
1395
1396    #[test]
1397    fn decode_variant_accepts_full_with_id_type_tag() {
1398        let decoder = PvdDecoder::new(false);
1399        // Variant payload: 0xFD + int16 key + string type + "ok"
1400        let data = [0xFD, 0x02, 0x00, 0x60, 0x02, b'o', b'k'];
1401        let (value, consumed) = decoder
1402            .decode_value(&data, &FieldType::Variant)
1403            .expect("decode variant");
1404        assert_eq!(consumed, data.len());
1405        assert!(matches!(value, DecodedValue::String(ref s) if s == "ok"));
1406    }
1407
1408    #[test]
1409    fn test_decode_bitset_whole_structure() {
1410        let decoder = PvdDecoder::new(false);
1411        let desc = StructureDesc {
1412            struct_id: None,
1413            fields: vec![FieldDesc {
1414                name: "value".to_string(),
1415                field_type: FieldType::Scalar(TypeCode::Float64),
1416            }],
1417        };
1418        // bitset_size=1, bitset=0x01 (whole structure), then float64 value.
1419        let mut data = Vec::new();
1420        data.push(0x01);
1421        data.push(0x01);
1422        data.extend_from_slice(&1.25f64.to_le_bytes());
1423
1424        let (decoded, _consumed) = decoder
1425            .decode_structure_with_bitset(&data, &desc)
1426            .expect("decoded");
1427        if let DecodedValue::Structure(fields) = decoded {
1428            assert_eq!(fields.len(), 1);
1429            assert_eq!(fields[0].0, "value");
1430        } else {
1431            panic!("expected structure");
1432        }
1433    }
1434
1435    #[test]
1436    fn format_structure_tree_includes_nested_fields() {
1437        let desc = StructureDesc {
1438            struct_id: Some("epics:nt/NTScalar:1.0".to_string()),
1439            fields: vec![
1440                FieldDesc {
1441                    name: "value".to_string(),
1442                    field_type: FieldType::Scalar(TypeCode::Float64),
1443                },
1444                FieldDesc {
1445                    name: "alarm".to_string(),
1446                    field_type: FieldType::Structure(StructureDesc {
1447                        struct_id: None,
1448                        fields: vec![
1449                            FieldDesc {
1450                                name: "severity".to_string(),
1451                                field_type: FieldType::Scalar(TypeCode::Int32),
1452                            },
1453                            FieldDesc {
1454                                name: "message".to_string(),
1455                                field_type: FieldType::String,
1456                            },
1457                        ],
1458                    }),
1459                },
1460            ],
1461        };
1462
1463        let rendered = format_structure_tree(&desc);
1464        assert!(rendered.contains("struct epics:nt/NTScalar:1.0"));
1465        assert!(rendered.contains("value: double"));
1466        assert!(rendered.contains("alarm: structure"));
1467        assert!(rendered.contains("severity: int"));
1468        assert!(rendered.contains("message: string"));
1469    }
1470
1471    #[test]
1472    fn decode_string_array_not_capped_at_100_items() {
1473        fn encode_size(size: usize) -> Vec<u8> {
1474            if size == 0 {
1475                return vec![0x00];
1476            }
1477            if size < 254 {
1478                return vec![size as u8];
1479            }
1480            let mut out = vec![0xFE];
1481            out.extend_from_slice(&(size as u32).to_le_bytes());
1482            out
1483        }
1484
1485        let item_count = 150usize;
1486        let mut raw = encode_size(item_count);
1487        for idx in 0..item_count {
1488            let s = format!("PV:{}", idx);
1489            raw.extend_from_slice(&encode_size(s.len()));
1490            raw.extend_from_slice(s.as_bytes());
1491        }
1492
1493        let decoder = PvdDecoder::new(false);
1494        let (decoded, _consumed) = decoder
1495            .decode_value(&raw, &FieldType::StringArray)
1496            .expect("decoded");
1497
1498        let DecodedValue::Array(items) = decoded else {
1499            panic!("expected decoded array");
1500        };
1501        assert_eq!(items.len(), item_count);
1502    }
1503}
spvirit_codec/spvd_decode.rs

spvirit_codec/
spvd_decode.rs
