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fpu: Add conversion routines for OCP FP4 E2M1

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Reviewed-by: Chao Liu <chao.liu.zevorn@gmail.com>
Signed-off-by: Max Chou <max.chou@sifive.com>
[rth: Update for exp_max_kind]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Max Chou
2026-02-05 21:10:46 +10:00
committed by Richard Henderson
parent 27e989f99c
commit b5fee33bbf
3 changed files with 30 additions and 1 deletions
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26
fpu/softfloat.c
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@@ -574,6 +574,11 @@ typedef struct {
.frac_shift = (-F - 1) & 63, \
.round_mask = (1ull << ((-F - 1) & 63)) - 1
static const FloatFmt float4_e2m1_params = {
FLOAT_PARAMS(2, 1),
.exp_max_kind = float_expmax_normal,
};
static const FloatFmt float8_e4m3_params = {
FLOAT_PARAMS(4, 3),
.exp_max_kind = float_expmax_e4m3
@@ -641,6 +646,11 @@ static void unpack_raw64(FloatParts64 *r, const FloatFmt *fmt, uint64_t raw)
};
}
static void QEMU_FLATTEN float4_e2m1_unpack_raw(FloatParts64 *p, float4_e2m1 f)
{
unpack_raw64(p, &float4_e2m1_params, f);
}
static void QEMU_FLATTEN float8_e4m3_unpack_raw(FloatParts64 *p, float8_e4m3 f)
{
unpack_raw64(p, &float8_e4m3_params, f);
@@ -1709,6 +1719,13 @@ static const uint16_t rsqrt_tab[128] = {
* Pack/unpack routines with a specific FloatFmt.
*/
static void float4_e2m1_unpack_canonical(FloatParts64 *p, float4_e2m1 f,
float_status *s)
{
float4_e2m1_unpack_raw(p, f);
parts_canonicalize(p, s, &float4_e2m1_params);
}
static void float8_e4m3_unpack_canonical(FloatParts64 *p, float8_e4m3 f,
float_status *s)
{
@@ -2929,6 +2946,15 @@ static void parts_float_to_float_widen(FloatParts128 *a, FloatParts64 *b,
}
}
float8_e4m3 float4_e2m1_to_float8_e4m3(float4_e2m1 a, float_status *s)
{
FloatParts64 p;
float4_e2m1_unpack_canonical(&p, a, s);
parts_float_to_float(&p, s);
return float8_e4m3_round_pack_canonical(&p, s, false);
}
bfloat16 float8_e4m3_to_bfloat16(float8_e4m3 a, float_status *s)
{
FloatParts64 p;

1
include/fpu/softfloat-types.h
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@@ -122,6 +122,7 @@ typedef uint16_t bfloat16;
/*
* Open Compute Project (OCP) Microscaling Formats
*/
typedef uint8_t float4_e2m1;
typedef uint8_t float8_e4m3;
typedef uint8_t float8_e5m2;

4
include/fpu/softfloat.h
View File

@@ -190,9 +190,11 @@ float128 uint64_to_float128(uint64_t, float_status *status);
float128 uint128_to_float128(Int128, float_status *status);
/*----------------------------------------------------------------------------
| OCP FP8 conversion routines.
| OCP FP{4,8} conversion routines.
*----------------------------------------------------------------------------*/
float8_e4m3 float4_e2m1_to_float8_e4m3(float4_e2m1, float_status *status);
bfloat16 float8_e4m3_to_bfloat16(float8_e4m3, float_status *status);
float8_e4m3 bfloat16_to_float8_e4m3(bfloat16, bool sat, float_status *status);
float8_e4m3 float32_to_float8_e4m3(float32, bool sat, float_status *status);