cauldron 0.0.1

Pure Rust Audio Decoder
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

use super::{Result, errors};

/// Converts an unsigned integer in the range 0-255 to a signed one in the range -128-127.
#[inline(always)]
pub fn signed_from_u8(x: u8) -> i8 {
    (x as i16 - 128) as i8
}

/// Converts a signed integer in the range -128-127 to an unsigned one in the range 0-255.
#[inline(always)]
pub fn u8_from_signed(x: i8) -> u8 {
    (x as i16 + 128) as u8
}

#[test]
fn u8_sign_conversion() {
    for x in 0..255 {
        assert_eq!(x, u8_from_signed(signed_from_u8(x)));
    }
    for x in -128..127 {
        assert_eq!(x, signed_from_u8(u8_from_signed(x)));
    }
}

/// Tries to cast the sample to an 8-bit signed integer, returning an error on overflow.
#[inline(always)]
pub fn narrow_to_i8(x: i32) -> Result<i8> {
    use std::i8;
    if x < i8::MIN as i32 || x > i8::MAX as i32 {
        errors::parse_error::<i8>("Too Wide to cast to i8")
    } else {
        Ok(x as i8)
    }
}

#[test]
fn verify_narrow_to_i8() {
    assert!(narrow_to_i8(127).is_ok());
    assert!(narrow_to_i8(128).is_err());
    assert!(narrow_to_i8(-128).is_ok());
    assert!(narrow_to_i8(-129).is_err());
}

/// Tries to cast the sample to a 16-bit signed integer, returning an error on overflow.
#[inline(always)]
pub fn narrow_to_i16(x: i32) -> Result<i16> {
    use std::i16;
    if x < i16::MIN as i32 || x > i16::MAX as i32 {
        errors::parse_error::<i16>("Too Wide to cast to i16")
    } else {
        Ok(x as i16)
    }
}

#[test]
fn verify_narrow_to_i16() {
    assert!(narrow_to_i16(32767).is_ok());
    assert!(narrow_to_i16(32768).is_err());
    assert!(narrow_to_i16(-32768).is_ok());
    assert!(narrow_to_i16(-32769).is_err());
}

/// Tries to cast the sample to a 24-bit signed integer, returning an error on overflow.
#[inline(always)]
pub fn narrow_to_i24(x: i32) -> Result<i32> {
    if x < -(1 << 23) || x > (1 << 23) - 1 {
        errors::parse_error::<i32>("Too Wide to cast to i24")
    } else {
        Ok(x)
    }
}

#[test]
fn verify_narrow_to_i24() {
    assert!(narrow_to_i24(8_388_607).is_ok());
    assert!(narrow_to_i24(8_388_608).is_err());
    assert!(narrow_to_i24(-8_388_608).is_ok());
    assert!(narrow_to_i24(-8_388_609).is_err());
}