oxigdal-gpu 0.1.6

GPU-accelerated geospatial operations for OxiGDAL using WGPU
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132

//! CPU-only tests for f16 buffer support in oxigdal-gpu.
//!
//! None of these tests require an actual GPU device.  They verify:
//! - `BufferElementType` metadata correctness
//! - f16 ↔ f32 conversion round-trips
//! - WGSL shader source generation (enable directive, type tokens)

use half::f16;
use oxigdal_gpu::BufferElementType;

// ---------------------------------------------------------------------------
// BufferElementType metadata
// ---------------------------------------------------------------------------

#[test]
fn test_buffer_element_type_byte_sizes() {
    assert_eq!(BufferElementType::F32.byte_size(), 4);
    assert_eq!(BufferElementType::F16.byte_size(), 2);
    assert_eq!(BufferElementType::U8.byte_size(), 1);
    assert_eq!(BufferElementType::U16.byte_size(), 2);
    assert_eq!(BufferElementType::U32.byte_size(), 4);
    assert_eq!(BufferElementType::I32.byte_size(), 4);
}

#[test]
fn test_buffer_element_type_wgsl_type_strings() {
    assert_eq!(BufferElementType::F32.wgsl_type(), "f32");
    assert_eq!(BufferElementType::F16.wgsl_type(), "f16");
    assert_eq!(BufferElementType::U32.wgsl_type(), "u32");
    assert_eq!(BufferElementType::I32.wgsl_type(), "i32");
    // u8 and u16 degrade to u32 in WGSL
    assert_eq!(BufferElementType::U8.wgsl_type(), "u32");
    assert_eq!(BufferElementType::U16.wgsl_type(), "u32");
}

// ---------------------------------------------------------------------------
// f16 ↔ f32 round-trip conversions
// ---------------------------------------------------------------------------

#[test]
fn test_f16_round_trip_within_1bit_lsb_via_widening() {
    use oxigdal_gpu::{f16_to_f32_slice, f32_to_f16_slice};
    let original: Vec<f16> = vec![f16::from_f32(1.5), f16::from_f32(2.25), f16::from_f32(-0.5)];
    let widened = f16_to_f32_slice(&original);
    let narrowed = f32_to_f16_slice(&widened);
    for (a, b) in original.iter().zip(narrowed.iter()) {
        assert_eq!(
            a.to_bits(),
            b.to_bits(),
            "bits must be exactly equal after round-trip for value {:?}",
            a
        );
    }
}

#[test]
fn test_f16_fallback_widens_to_f32_conversion_is_correct() {
    use oxigdal_gpu::f16_to_f32_slice;
    // Use 1.1 — not exactly representable in f16 but well within range.
    // f16 has ~3.3 decimal digits of precision, so 1.1 should round-trip
    // with an absolute error less than 0.01.
    let input_val = 1.1_f32;
    let halfs = vec![f16::from_f32(input_val)];
    let f32s = f16_to_f32_slice(&halfs);
    assert!(
        (f32s[0] - input_val).abs() < 0.01,
        "widened value {} is too far from {}",
        f32s[0],
        input_val
    );
}

#[test]
fn test_f16_to_f32_to_f16_idempotent_for_representable_values() {
    use oxigdal_gpu::{f16_to_f32_slice, f32_to_f16_slice};
    // Values that are exactly representable in f16
    let representable = vec![0.0_f32, 1.0, 2.0, -4.0, 0.5, 0.25];
    let as_f16 = f32_to_f16_slice(&representable);
    let as_f32 = f16_to_f32_slice(&as_f16);
    let back = f32_to_f16_slice(&as_f32);
    for (a, b) in as_f16.iter().zip(back.iter()) {
        assert_eq!(
            a.to_bits(),
            b.to_bits(),
            "idempotent round-trip failed for {:?}",
            a
        );
    }
}

// ---------------------------------------------------------------------------
// WGSL shader source generation
// ---------------------------------------------------------------------------

#[test]
fn test_f16_kernel_source_contains_enable_directive_when_f16() {
    use oxigdal_gpu::make_element_wise_shader_source;
    let src = make_element_wise_shader_source(BufferElementType::F16);
    assert!(
        src.contains("enable f16"),
        "WGSL source must contain 'enable f16'; got:\n{src}"
    );
    assert!(
        src.contains("array<f16>"),
        "WGSL source must reference array<f16>; got:\n{src}"
    );
}

#[test]
fn test_f32_kernel_source_does_not_contain_enable_f16() {
    use oxigdal_gpu::make_element_wise_shader_source;
    let src = make_element_wise_shader_source(BufferElementType::F32);
    assert!(
        !src.contains("enable f16"),
        "F32 shader must not have 'enable f16'; got:\n{src}"
    );
    assert!(
        src.contains("array<f32>"),
        "F32 shader must reference array<f32>; got:\n{src}"
    );
}

#[test]
fn test_u32_kernel_source_does_not_contain_enable_f16() {
    use oxigdal_gpu::make_element_wise_shader_source;
    let src = make_element_wise_shader_source(BufferElementType::U32);
    assert!(
        !src.contains("enable f16"),
        "U32 shader must not have 'enable f16'; got:\n{src}"
    );
    assert!(src.contains("array<u32>"));
}