diff options
Diffstat (limited to 'gsk/ngl/fp16.c')
| -rw-r--r-- | gsk/ngl/fp16.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/gsk/ngl/fp16.c b/gsk/ngl/fp16.c new file mode 100644 index 0000000000..e9a8c8fbce --- /dev/null +++ b/gsk/ngl/fp16.c @@ -0,0 +1,150 @@ +/* fp16.c + * + * Copyright 2021 Red Hat, Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this program. If not, see <http://www.gnu.org/licenses/>. + * + * SPDX-License-Identifier: LGPL-2.1-or-later + */ + +#include <config.h> + +#include "fp16private.h" + +#ifdef HAVE_F16C +#include <immintrin.h> +#endif + +static inline guint +as_uint (const float x) +{ + return *(guint*)&x; +} + +static inline float +as_float (const guint x) +{ + return *(float*)&x; +} + +// IEEE-754 16-bit floating-point format (without infinity): 1-5-10 + +static inline float +half_to_float (const guint16 x) +{ + const guint e = (x&0x7C00)>>10; // exponent + const guint m = (x&0x03FF)<<13; // mantissa + const guint v = as_uint((float)m)>>23; + return as_float((x&0x8000)<<16 | (e!=0)*((e+112)<<23|m) | ((e==0)&(m!=0))*((v-37)<<23|((m<<(150-v))&0x007FE000))); +} + +static inline guint16 +float_to_half (const float x) +{ + const guint b = as_uint(x)+0x00001000; // round-to-nearest-even + const guint e = (b&0x7F800000)>>23; // exponent + const guint m = b&0x007FFFFF; // mantissa + return (b&0x80000000)>>16 | (e>112)*((((e-112)<<10)&0x7C00)|m>>13) | ((e<113)&(e>101))*((((0x007FF000+m)>>(125-e))+1)>>1) | (e>143)*0x7FFF; // sign : normalized : denormalized : saturate +} + +static void +float_to_half4_c (const float f[4], + guint16 h[4]) +{ + h[0] = float_to_half (f[0]); + h[1] = float_to_half (f[1]); + h[2] = float_to_half (f[2]); + h[3] = float_to_half (f[3]); +} + +static void +half_to_float4_c (const guint16 h[4], + float f[4]) +{ + f[0] = half_to_float (h[0]); + f[1] = half_to_float (h[1]); + f[2] = half_to_float (h[2]); + f[3] = half_to_float (h[3]); +} + +#ifdef HAVE_F16C + +static void +float_to_half4_f16c (const float f[4], + guint16 h[4]) +{ + __m128 s = _mm_loadu_ps (f); + __m128i i = _mm_cvtps_ph (s, 0); + _mm_storel_epi64 ((__m128i*)h, i); +} + +static void +half_to_float4_f16c (const guint16 h[4], + float f[4]) +{ + __m128i i = _mm_loadl_epi64 ((__m128i_u const *)h); + __m128 s = _mm_cvtph_ps (i); + _mm_store_ps (f, s); +} + +void float_to_half4 (const float f[4], guint16 h[4]) __attribute__((ifunc ("resolve_float_to_half4"))); +void half_to_float4 (const guint16 h[4], float f[4]) __attribute__((ifunc ("resolve_half_to_float4"))); + +static void * +resolve_float_to_half4 (void) +{ + __builtin_cpu_init (); + if (__builtin_cpu_supports ("f16c")) + return float_to_half4_f16c; + else + return float_to_half4_c; +} + +static void * +resolve_half_to_float4 (void) +{ + __builtin_cpu_init (); + if (__builtin_cpu_supports ("f16c")) + return half_to_float4_f16c; + else + return half_to_float4_c; +} + +#else + +#ifdef __APPLE__ +// turns out aliases don't work on Darwin + +void +float_to_half4 (const float f[4], + guint16 h[4]) +{ + float_to_half4_c (f, h); +} + +void +half_to_float4 (const guint16 h[4], + float f[4]) +{ + half_to_float4_c (h, f); +} + +#else + +void float_to_half4 (const float f[4], guint16 h[4]) __attribute__((alias ("float_to_half4_c"))); +void half_to_float4 (const guint16 h[4], float f[4]) __attribute__((alias ("half_to_float4_c"))); + +#endif + +#endif /* GTK_HAS_F16C */ |