181 lines · c
1//===-lib/fp_extend.h - low precision -> high precision conversion -*- C2//-*-===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9//10// Set source and destination setting11//12//===----------------------------------------------------------------------===//13 14#ifndef FP_EXTEND_HEADER15#define FP_EXTEND_HEADER16 17#include "int_lib.h"18 19#if defined SRC_SINGLE20typedef float src_t;21typedef uint32_t src_rep_t;22#define SRC_REP_C UINT32_C23static const int srcBits = sizeof(src_t) * CHAR_BIT;24static const int srcSigFracBits = 23;25// -1 accounts for the sign bit.26// srcBits - srcSigFracBits - 127static const int srcExpBits = 8;28#define src_rep_t_clz clzsi29 30#elif defined SRC_DOUBLE31typedef double src_t;32typedef uint64_t src_rep_t;33#define SRC_REP_C UINT64_C34static const int srcBits = sizeof(src_t) * CHAR_BIT;35static const int srcSigFracBits = 52;36// -1 accounts for the sign bit.37// srcBits - srcSigFracBits - 138static const int srcExpBits = 11;39 40static inline int src_rep_t_clz_impl(src_rep_t a) { return __builtin_clzll(a); }41#define src_rep_t_clz src_rep_t_clz_impl42 43#elif defined SRC_8044typedef xf_float src_t;45typedef __uint128_t src_rep_t;46#define SRC_REP_C (__uint128_t)47// sign bit, exponent and significand occupy the lower 80 bits.48static const int srcBits = 80;49static const int srcSigFracBits = 63;50// -1 accounts for the sign bit.51// -1 accounts for the explicitly stored integer bit.52// srcBits - srcSigFracBits - 1 - 153static const int srcExpBits = 15;54 55#elif defined SRC_HALF56#ifdef COMPILER_RT_HAS_FLOAT1657typedef _Float16 src_t;58#else59typedef uint16_t src_t;60#endif61typedef uint16_t src_rep_t;62#define SRC_REP_C UINT16_C63static const int srcBits = sizeof(src_t) * CHAR_BIT;64static const int srcSigFracBits = 10;65// -1 accounts for the sign bit.66// srcBits - srcSigFracBits - 167static const int srcExpBits = 5;68 69static inline int src_rep_t_clz_impl(src_rep_t a) {70 return __builtin_clz(a) - 16;71}72 73#define src_rep_t_clz src_rep_t_clz_impl74 75#elif defined SRC_BFLOAT1676#ifdef COMPILER_RT_HAS_BFLOAT1677typedef __bf16 src_t;78#else79typedef uint16_t src_t;80#endif81typedef uint16_t src_rep_t;82#define SRC_REP_C UINT16_C83static const int srcBits = sizeof(src_t) * CHAR_BIT;84static const int srcSigFracBits = 7;85// -1 accounts for the sign bit.86// srcBits - srcSigFracBits - 187static const int srcExpBits = 8;88#define src_rep_t_clz __builtin_clz89 90#else91#error Source should be half, single, or double precision!92#endif // end source precision93 94#if defined DST_SINGLE95typedef float dst_t;96typedef uint32_t dst_rep_t;97#define DST_REP_C UINT32_C98static const int dstBits = sizeof(dst_t) * CHAR_BIT;99static const int dstSigFracBits = 23;100// -1 accounts for the sign bit.101// dstBits - dstSigFracBits - 1102static const int dstExpBits = 8;103 104#elif defined DST_DOUBLE105typedef double dst_t;106typedef uint64_t dst_rep_t;107#define DST_REP_C UINT64_C108static const int dstBits = sizeof(dst_t) * CHAR_BIT;109static const int dstSigFracBits = 52;110// -1 accounts for the sign bit.111// dstBits - dstSigFracBits - 1112static const int dstExpBits = 11;113 114#elif defined DST_QUAD115typedef tf_float dst_t;116typedef __uint128_t dst_rep_t;117#define DST_REP_C (__uint128_t)118static const int dstBits = sizeof(dst_t) * CHAR_BIT;119static const int dstSigFracBits = 112;120// -1 accounts for the sign bit.121// dstBits - dstSigFracBits - 1122static const int dstExpBits = 15;123 124#else125#error Destination should be single, double, or quad precision!126#endif // end destination precision127 128// End of specialization parameters.129 130// TODO: These helper routines should be placed into fp_lib.h131// Currently they depend on macros/constants defined above.132 133static inline src_rep_t extract_sign_from_src(src_rep_t x) {134 const src_rep_t srcSignMask = SRC_REP_C(1) << (srcBits - 1);135 return (x & srcSignMask) >> (srcBits - 1);136}137 138static inline src_rep_t extract_exp_from_src(src_rep_t x) {139 const int srcSigBits = srcBits - 1 - srcExpBits;140 const src_rep_t srcExpMask = ((SRC_REP_C(1) << srcExpBits) - 1) << srcSigBits;141 return (x & srcExpMask) >> srcSigBits;142}143 144static inline src_rep_t extract_sig_frac_from_src(src_rep_t x) {145 const src_rep_t srcSigFracMask = (SRC_REP_C(1) << srcSigFracBits) - 1;146 return x & srcSigFracMask;147}148 149#ifdef src_rep_t_clz150static inline int clz_in_sig_frac(src_rep_t sigFrac) {151 const int skip = 1 + srcExpBits;152 return src_rep_t_clz(sigFrac) - skip;153}154#endif155 156static inline dst_rep_t construct_dst_rep(dst_rep_t sign, dst_rep_t exp, dst_rep_t sigFrac) {157 return (sign << (dstBits - 1)) | (exp << (dstBits - 1 - dstExpBits)) | sigFrac;158}159 160// Two helper routines for conversion to and from the representation of161// floating-point data as integer values follow.162 163static inline src_rep_t srcToRep(src_t x) {164 const union {165 src_t f;166 src_rep_t i;167 } rep = {.f = x};168 return rep.i;169}170 171static inline dst_t dstFromRep(dst_rep_t x) {172 const union {173 dst_t f;174 dst_rep_t i;175 } rep = {.i = x};176 return rep.f;177}178// End helper routines. Conversion implementation follows.179 180#endif // FP_EXTEND_HEADER181