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
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
//! Traits and helper functions related to floats.

use crate::vector::Vector;
#[cfg(target_arch = "spirv")]
use core::arch::asm;

/// Abstract trait representing a SPIR-V floating point type.
///
/// # Safety
/// Implementing this trait on non-primitive-float types breaks assumptions of other unsafe code,
/// and should not be done.
pub unsafe trait Float: num_traits::Float + crate::scalar::Scalar + Default {
    /// Width of the float, in bits.
    const WIDTH: usize;
}

unsafe impl Float for f32 {
    const WIDTH: usize = 32;
}

unsafe impl Float for f64 {
    const WIDTH: usize = 64;
}

/// Converts two f32 values (floats) into two f16 values (halfs). The result is a u32, with the low
/// 16 bits being the first f16, and the high 16 bits being the second f16.
#[spirv_std_macros::gpu_only]
pub fn vec2_to_f16x2(vec: impl Vector<f32, 2>) -> u32 {
    let result;
    unsafe {
        asm!(
            "%glsl = OpExtInstImport \"GLSL.std.450\"",
            "%uint = OpTypeInt 32 0",
            "%vec = OpLoad _ {vec}",
            // 58 = PackHalf2x16
            "{result} = OpExtInst %uint %glsl 58 %vec",
            vec = in(reg) &vec,
            result = out(reg) result,
        );
    }
    result
}

/// Converts two f16 values (halfs) into two f32 values (floats). The parameter is a u32, with the
/// low 16 bits being the first f16, and the high 16 bits being the second f16.
#[spirv_std_macros::gpu_only]
pub fn f16x2_to_vec2<V: Vector<f32, 2>>(int: u32) -> V {
    let mut result = Default::default();
    unsafe {
        asm!(
            "%glsl = OpExtInstImport \"GLSL.std.450\"",
            "%float = OpTypeFloat 32",
            "%vec2 = OpTypeVector %float 2",
            // 62 = UnpackHalf2x16
            "%result = OpExtInst %vec2 %glsl 62 {int}",
            "OpStore {result} %result",
            int = in(reg) int,
            result = in(reg) &mut result,
        );
    }
    result
}

/// Converts an f32 (float) into an f16 (half). The result is a u32, not a u16, due to GPU support
/// for u16 not being universal - the upper 16 bits will always be zero.
#[spirv_std_macros::gpu_only]
pub fn f32_to_f16(float: f32) -> u32 {
    vec2_to_f16x2(glam::Vec2::new(float, 0.))
}

/// Converts an f16 (half) into an f32 (float). The parameter is a u32, due to GPU support for u16
/// not being universal - the upper 16 bits are ignored.
#[spirv_std_macros::gpu_only]
pub fn f16_to_f32(packed: u32) -> f32 {
    f16x2_to_vec2::<glam::Vec2>(packed).x
}

/// Packs a vec4 into 4 8-bit signed integers. See
/// [PackSnorm4x8](https://www.khronos.org/registry/SPIR-V/specs/1.0/GLSL.std.450.html) for exact
/// semantics.
#[spirv_std_macros::gpu_only]
pub fn vec4_to_u8x4_snorm(vec: impl Vector<f32, 4>) -> u32 {
    let result;
    unsafe {
        asm!(
            "%glsl = OpExtInstImport \"GLSL.std.450\"",
            "%uint = OpTypeInt 32 0",
            "%vec = OpLoad _ {vec}",
            // 54 = PackSnorm4x8
            "{result} = OpExtInst %uint %glsl 54 %vec",
            vec = in(reg) &vec,
            result = out(reg) result,
        );
    }
    result
}

/// Packs a vec4 into 4 8-bit unsigned integers. See
/// [PackUnorm4x8](https://www.khronos.org/registry/SPIR-V/specs/1.0/GLSL.std.450.html) for exact
/// semantics.
#[spirv_std_macros::gpu_only]
pub fn vec4_to_u8x4_unorm(vec: impl Vector<f32, 4>) -> u32 {
    let result;
    unsafe {
        asm!(
            "%glsl = OpExtInstImport \"GLSL.std.450\"",
            "%uint = OpTypeInt 32 0",
            "%vec = OpLoad _ {vec}",
            // 55 = PackUnorm4x8
            "{result} = OpExtInst %uint %glsl 55 %vec",
            vec = in(reg) &vec,
            result = out(reg) result,
        );
    }
    result
}

/// Packs a vec2 into 2 16-bit signed integers. See
/// [PackSnorm2x16](https://www.khronos.org/registry/SPIR-V/specs/1.0/GLSL.std.450.html) for exact
/// semantics.
#[spirv_std_macros::gpu_only]
pub fn vec2_to_u16x2_snorm(vec: impl Vector<f32, 2>) -> u32 {
    let result;
    unsafe {
        asm!(
            "%glsl = OpExtInstImport \"GLSL.std.450\"",
            "%uint = OpTypeInt 32 0",
            "%vec = OpLoad _ {vec}",
            // 56 = PackSnorm2x16
            "{result} = OpExtInst %uint %glsl 56 %vec",
            vec = in(reg) &vec,
            result = out(reg) result,
        );
    }
    result
}

/// Packs a vec2 into 2 16-bit unsigned integers. See
/// [PackUnorm2x16](https://www.khronos.org/registry/SPIR-V/specs/1.0/GLSL.std.450.html) for exact
/// semantics.
#[spirv_std_macros::gpu_only]
pub fn vec2_to_u16x2_unorm(vec: impl Vector<f32, 2>) -> u32 {
    let result;
    unsafe {
        asm!(
            "%glsl = OpExtInstImport \"GLSL.std.450\"",
            "%uint = OpTypeInt 32 0",
            "%vec = OpLoad _ {vec}",
            // 57 = PackUnorm2x16
            "{result} = OpExtInst %uint %glsl 57 %vec",
            vec = in(reg) &vec,
            result = out(reg) result,
        );
    }
    result
}

/// Unpacks 4 8-bit signed integers into a vec4. See
/// [UnpackSnorm4x8](https://www.khronos.org/registry/SPIR-V/specs/1.0/GLSL.std.450.html) for exact
/// semantics.
#[spirv_std_macros::gpu_only]
pub fn u8x4_to_vec4_snorm<V: Vector<f32, 4>>(int: u32) -> V {
    let mut result = Default::default();
    unsafe {
        asm!(
            "%glsl = OpExtInstImport \"GLSL.std.450\"",
            "%float = OpTypeFloat 32",
            "%vec4 = OpTypeVector %float 4",
            // 63 = UnpackSnorm4x8
            "%result = OpExtInst %vec4 %glsl 63 {int}",
            "OpStore {result} %result",
            int = in(reg) int,
            result = in(reg) &mut result,
        );
    }
    result
}

/// Unpacks 4 8-bit unsigned integers into a vec4. See
/// [UnpackSnorm4x8](https://www.khronos.org/registry/SPIR-V/specs/1.0/GLSL.std.450.html) for exact
/// semantics.
#[spirv_std_macros::gpu_only]
pub fn u8x4_to_vec4_unorm<V: Vector<f32, 4>>(int: u32) -> V {
    let mut result = Default::default();
    unsafe {
        asm!(
            "%glsl = OpExtInstImport \"GLSL.std.450\"",
            "%float = OpTypeFloat 32",
            "%vec4 = OpTypeVector %float 4",
            // 64 = UnpackUnorm4x8
            "%result = OpExtInst %vec4 %glsl 64 {int}",
            "OpStore {result} %result",
            int = in(reg) int,
            result = in(reg) &mut result,
        );
    }
    result
}

/// Unpacks 2 16-bit signed integers into a vec2. See
/// [UnpackSnorm2x16](https://www.khronos.org/registry/SPIR-V/specs/1.0/GLSL.std.450.html) for
/// exact semantics.
#[spirv_std_macros::gpu_only]
pub fn u16x2_to_vec2_snorm<V: Vector<f32, 2>>(int: u32) -> V {
    let mut result = Default::default();
    unsafe {
        asm!(
            "%glsl = OpExtInstImport \"GLSL.std.450\"",
            "%float = OpTypeFloat 32",
            "%vec2 = OpTypeVector %float 2",
            // 60 = UnpackSnorm2x16
            "%result = OpExtInst %vec2 %glsl 60 {int}",
            "OpStore {result} %result",
            int = in(reg) int,
            result = in(reg) &mut result,
        );
    }
    result
}

/// Unpacks 2 16-bit unsigned integers into a vec2. See
/// [UnpackUnorm2x16](https://www.khronos.org/registry/SPIR-V/specs/1.0/GLSL.std.450.html) for
/// exact semantics.
#[spirv_std_macros::gpu_only]
pub fn u16x2_to_vec2_unorm<V: Vector<f32, 2>>(int: u32) -> V {
    let mut result = Default::default();
    unsafe {
        asm!(
            "%glsl = OpExtInstImport \"GLSL.std.450\"",
            "%float = OpTypeFloat 32",
            "%vec2 = OpTypeVector %float 2",
            // 61 = UnpackUnorm2x16
            "%result = OpExtInst %vec2 %glsl 61 {int}",
            "OpStore {result} %result",
            int = in(reg) int,
            result = in(reg) &mut result,
        );
    }
    result
}