cosmopolitan/third_party/compiler_rt/floatsidf.c

65 lines
1.9 KiB
C

/* clang-format off */
//===-- lib/floatsidf.c - integer -> double-precision conversion --*- C -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements integer to double-precision conversion for the
// compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even
// mode.
//
//===----------------------------------------------------------------------===//
STATIC_YOINK("huge_compiler_rt_license");
#define DOUBLE_PRECISION
#include "third_party/compiler_rt/fp_lib.inc"
#include "third_party/compiler_rt/int_lib.h"
COMPILER_RT_ABI fp_t
__floatsidf(int a) {
const int aWidth = sizeof a * CHAR_BIT;
// Handle zero as a special case to protect clz
if (a == 0)
return fromRep(0);
// All other cases begin by extracting the sign and absolute value of a
rep_t sign = 0;
if (a < 0) {
sign = signBit;
a = -a;
}
// Exponent of (fp_t)a is the width of abs(a).
const int exponent = (aWidth - 1) - __builtin_clz(a);
rep_t result;
// Shift a into the significand field and clear the implicit bit. Extra
// cast to unsigned int is necessary to get the correct behavior for
// the input INT_MIN.
const int shift = significandBits - exponent;
result = (rep_t)(unsigned int)a << shift ^ implicitBit;
// Insert the exponent
result += (rep_t)(exponent + exponentBias) << significandBits;
// Insert the sign bit and return
return fromRep(result | sign);
}
#if defined(__ARM_EABI__)
#if defined(COMPILER_RT_ARMHF_TARGET)
AEABI_RTABI fp_t __aeabi_i2d(int a) {
return __floatsidf(a);
}
#else
AEABI_RTABI fp_t __aeabi_i2d(int a) COMPILER_RT_ALIAS(__floatsidf);
#endif
#endif