1//
2// Copyright (c) 2002-2011 The ANGLE Project Authors. All rights reserved.
3// Use of this source code is governed by a BSD-style license that can be
4// found in the LICENSE file.
5//
6
7#include "compiler/translator/BuiltInFunctionEmulatorGLSL.h"
8
9#include "angle_gl.h"
10#include "compiler/translator/BuiltInFunctionEmulator.h"
11#include "compiler/translator/VersionGLSL.h"
12#include "compiler/translator/tree_util/BuiltIn_autogen.h"
13
14namespace sh
15{
16
17void InitBuiltInAbsFunctionEmulatorForGLSLWorkarounds(BuiltInFunctionEmulator *emu,
18 sh::GLenum shaderType)
19{
20 if (shaderType == GL_VERTEX_SHADER)
21 {
22 emu->addEmulatedFunction(BuiltInId::abs_Int1, "int abs_emu(int x) { return x * sign(x); }");
23 }
24}
25
26void InitBuiltInIsnanFunctionEmulatorForGLSLWorkarounds(BuiltInFunctionEmulator *emu,
27 int targetGLSLVersion)
28{
29 // isnan() is supported since GLSL 1.3.
30 if (targetGLSLVersion < GLSL_VERSION_130)
31 return;
32
33 // !(x > 0.0 || x < 0.0 || x == 0.0) will be optimized and always equal to false.
34 emu->addEmulatedFunction(
35 BuiltInId::isnan_Float1,
36 "bool isnan_emu(float x) { return (x > 0.0 || x < 0.0) ? false : x != 0.0; }");
37 emu->addEmulatedFunction(
38 BuiltInId::isnan_Float2,
39 "bvec2 isnan_emu(vec2 x)\n"
40 "{\n"
41 " bvec2 isnan;\n"
42 " for (int i = 0; i < 2; i++)\n"
43 " {\n"
44 " isnan[i] = (x[i] > 0.0 || x[i] < 0.0) ? false : x[i] != 0.0;\n"
45 " }\n"
46 " return isnan;\n"
47 "}\n");
48 emu->addEmulatedFunction(
49 BuiltInId::isnan_Float3,
50 "bvec3 isnan_emu(vec3 x)\n"
51 "{\n"
52 " bvec3 isnan;\n"
53 " for (int i = 0; i < 3; i++)\n"
54 " {\n"
55 " isnan[i] = (x[i] > 0.0 || x[i] < 0.0) ? false : x[i] != 0.0;\n"
56 " }\n"
57 " return isnan;\n"
58 "}\n");
59 emu->addEmulatedFunction(
60 BuiltInId::isnan_Float4,
61 "bvec4 isnan_emu(vec4 x)\n"
62 "{\n"
63 " bvec4 isnan;\n"
64 " for (int i = 0; i < 4; i++)\n"
65 " {\n"
66 " isnan[i] = (x[i] > 0.0 || x[i] < 0.0) ? false : x[i] != 0.0;\n"
67 " }\n"
68 " return isnan;\n"
69 "}\n");
70}
71
72void InitBuiltInAtanFunctionEmulatorForGLSLWorkarounds(BuiltInFunctionEmulator *emu)
73{
74 emu->addEmulatedFunction(BuiltInId::atan_Float1_Float1,
75 "emu_precision float atan_emu(emu_precision float y, emu_precision "
76 "float x)\n"
77 "{\n"
78 " if (x > 0.0) return atan(y / x);\n"
79 " else if (x < 0.0 && y >= 0.0) return atan(y / x) + 3.14159265;\n"
80 " else if (x < 0.0 && y < 0.0) return atan(y / x) - 3.14159265;\n"
81 " else return 1.57079632 * sign(y);\n"
82 "}\n");
83 static const std::array<TSymbolUniqueId, 4> ids = {
84 BuiltInId::atan_Float1_Float1,
85 BuiltInId::atan_Float2_Float2,
86 BuiltInId::atan_Float3_Float3,
87 BuiltInId::atan_Float4_Float4,
88 };
89 for (int dim = 2; dim <= 4; ++dim)
90 {
91 std::stringstream ss = sh::InitializeStream<std::stringstream>();
92 ss << "emu_precision vec" << dim << " atan_emu(emu_precision vec" << dim
93 << " y, emu_precision vec" << dim << " x)\n"
94 << "{\n"
95 " return vec"
96 << dim << "(";
97 for (int i = 0; i < dim; ++i)
98 {
99 ss << "atan_emu(y[" << i << "], x[" << i << "])";
100 if (i < dim - 1)
101 {
102 ss << ", ";
103 }
104 }
105 ss << ");\n"
106 "}\n";
107 emu->addEmulatedFunctionWithDependency(BuiltInId::atan_Float1_Float1, ids[dim - 1],
108 ss.str().c_str());
109 }
110}
111
112// Emulate built-in functions missing from GLSL 1.30 and higher
113void InitBuiltInFunctionEmulatorForGLSLMissingFunctions(BuiltInFunctionEmulator *emu,
114 sh::GLenum shaderType,
115 int targetGLSLVersion)
116{
117 // Emulate packUnorm2x16 and unpackUnorm2x16 (GLSL 4.10)
118 if (targetGLSLVersion < GLSL_VERSION_410)
119 {
120 // clang-format off
121 emu->addEmulatedFunction(BuiltInId::packUnorm2x16_Float2,
122 "uint packUnorm2x16_emu(vec2 v)\n"
123 "{\n"
124 " int x = int(round(clamp(v.x, 0.0, 1.0) * 65535.0));\n"
125 " int y = int(round(clamp(v.y, 0.0, 1.0) * 65535.0));\n"
126 " return uint((y << 16) | (x & 0xFFFF));\n"
127 "}\n");
128
129 emu->addEmulatedFunction(BuiltInId::unpackUnorm2x16_UInt1,
130 "vec2 unpackUnorm2x16_emu(uint u)\n"
131 "{\n"
132 " float x = float(u & 0xFFFFu) / 65535.0;\n"
133 " float y = float(u >> 16) / 65535.0;\n"
134 " return vec2(x, y);\n"
135 "}\n");
136 // clang-format on
137 }
138
139 // Emulate packSnorm2x16, packHalf2x16, unpackSnorm2x16, and unpackHalf2x16 (GLSL 4.20)
140 // by using floatBitsToInt, floatBitsToUint, intBitsToFloat, and uintBitsToFloat (GLSL 3.30).
141 if (targetGLSLVersion >= GLSL_VERSION_330 && targetGLSLVersion < GLSL_VERSION_420)
142 {
143 // clang-format off
144 emu->addEmulatedFunction(BuiltInId::packSnorm2x16_Float2,
145 "uint packSnorm2x16_emu(vec2 v)\n"
146 "{\n"
147 " #if defined(GL_ARB_shading_language_packing)\n"
148 " return packSnorm2x16(v);\n"
149 " #else\n"
150 " int x = int(round(clamp(v.x, -1.0, 1.0) * 32767.0));\n"
151 " int y = int(round(clamp(v.y, -1.0, 1.0) * 32767.0));\n"
152 " return uint((y << 16) | (x & 0xFFFF));\n"
153 " #endif\n"
154 "}\n");
155 emu->addEmulatedFunction(BuiltInId::unpackSnorm2x16_UInt1,
156 "#if !defined(GL_ARB_shading_language_packing)\n"
157 " float fromSnorm(uint x)\n"
158 " {\n"
159 " int xi = (int(x) & 0x7FFF) - (int(x) & 0x8000);\n"
160 " return clamp(float(xi) / 32767.0, -1.0, 1.0);\n"
161 " }\n"
162 "#endif\n"
163 "\n"
164 "vec2 unpackSnorm2x16_emu(uint u)\n"
165 "{\n"
166 " #if defined(GL_ARB_shading_language_packing)\n"
167 " return unpackSnorm2x16(u);\n"
168 " #else\n"
169 " uint y = (u >> 16);\n"
170 " uint x = u;\n"
171 " return vec2(fromSnorm(x), fromSnorm(y));\n"
172 " #endif\n"
173 "}\n");
174 // Functions uint f32tof16(float val) and float f16tof32(uint val) are
175 // based on the OpenGL redbook Appendix Session "Floating-Point Formats Used in OpenGL".
176 emu->addEmulatedFunction(BuiltInId::packHalf2x16_Float2,
177 "#if !defined(GL_ARB_shading_language_packing)\n"
178 " uint f32tof16(float val)\n"
179 " {\n"
180 " uint f32 = floatBitsToUint(val);\n"
181 " uint f16 = 0u;\n"
182 " uint sign = (f32 >> 16) & 0x8000u;\n"
183 " int exponent = int((f32 >> 23) & 0xFFu) - 127;\n"
184 " uint mantissa = f32 & 0x007FFFFFu;\n"
185 " if (exponent == 128)\n"
186 " {\n"
187 " // Infinity or NaN\n"
188 " // NaN bits that are masked out by 0x3FF get discarded.\n"
189 " // This can turn some NaNs to infinity, but this is allowed by the spec.\n"
190 " f16 = sign | (0x1Fu << 10);\n"
191 " f16 |= (mantissa & 0x3FFu);\n"
192 " }\n"
193 " else if (exponent > 15)\n"
194 " {\n"
195 " // Overflow - flush to Infinity\n"
196 " f16 = sign | (0x1Fu << 10);\n"
197 " }\n"
198 " else if (exponent > -15)\n"
199 " {\n"
200 " // Representable value\n"
201 " exponent += 15;\n"
202 " mantissa >>= 13;\n"
203 " f16 = sign | uint(exponent << 10) | mantissa;\n"
204 " }\n"
205 " else\n"
206 " {\n"
207 " f16 = sign;\n"
208 " }\n"
209 " return f16;\n"
210 " }\n"
211 "#endif\n"
212 "\n"
213 "uint packHalf2x16_emu(vec2 v)\n"
214 "{\n"
215 " #if defined(GL_ARB_shading_language_packing)\n"
216 " return packHalf2x16(v);\n"
217 " #else\n"
218 " uint x = f32tof16(v.x);\n"
219 " uint y = f32tof16(v.y);\n"
220 " return (y << 16) | x;\n"
221 " #endif\n"
222 "}\n");
223 emu->addEmulatedFunction(BuiltInId::unpackHalf2x16_UInt1,
224 "#if !defined(GL_ARB_shading_language_packing)\n"
225 " float f16tof32(uint val)\n"
226 " {\n"
227 " uint sign = (val & 0x8000u) << 16;\n"
228 " int exponent = int((val & 0x7C00u) >> 10);\n"
229 " uint mantissa = val & 0x03FFu;\n"
230 " float f32 = 0.0;\n"
231 " if(exponent == 0)\n"
232 " {\n"
233 " if (mantissa != 0u)\n"
234 " {\n"
235 " const float scale = 1.0 / (1 << 24);\n"
236 " f32 = scale * mantissa;\n"
237 " }\n"
238 " }\n"
239 " else if (exponent == 31)\n"
240 " {\n"
241 " return uintBitsToFloat(sign | 0x7F800000u | mantissa);\n"
242 " }\n"
243 " else\n"
244 " {\n"
245 " exponent -= 15;\n"
246 " float scale;\n"
247 " if(exponent < 0)\n"
248 " {\n"
249 " // The negative unary operator is buggy on OSX.\n"
250 " // Work around this by using abs instead.\n"
251 " scale = 1.0 / (1 << abs(exponent));\n"
252 " }\n"
253 " else\n"
254 " {\n"
255 " scale = 1 << exponent;\n"
256 " }\n"
257 " float decimal = 1.0 + float(mantissa) / float(1 << 10);\n"
258 " f32 = scale * decimal;\n"
259 " }\n"
260 "\n"
261 " if (sign != 0u)\n"
262 " {\n"
263 " f32 = -f32;\n"
264 " }\n"
265 "\n"
266 " return f32;\n"
267 " }\n"
268 "#endif\n"
269 "\n"
270 "vec2 unpackHalf2x16_emu(uint u)\n"
271 "{\n"
272 " #if defined(GL_ARB_shading_language_packing)\n"
273 " return unpackHalf2x16(u);\n"
274 " #else\n"
275 " uint y = (u >> 16);\n"
276 " uint x = u & 0xFFFFu;\n"
277 " return vec2(f16tof32(x), f16tof32(y));\n"
278 " #endif\n"
279 "}\n");
280 // clang-format on
281 }
282}
283
284} // namespace sh
285