xref: /freebsd/contrib/llvm-project/compiler-rt/lib/builtins/floatsidf.c (revision 5ffd83dbcc34f10e07f6d3e968ae6365869615f4)
10b57cec5SDimitry Andric //===-- lib/floatsidf.c - integer -> double-precision conversion --*- C -*-===//
20b57cec5SDimitry Andric //
30b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
40b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
50b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
60b57cec5SDimitry Andric //
70b57cec5SDimitry Andric //===----------------------------------------------------------------------===//
80b57cec5SDimitry Andric //
90b57cec5SDimitry Andric // This file implements integer to double-precision conversion for the
100b57cec5SDimitry Andric // compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even
110b57cec5SDimitry Andric // mode.
120b57cec5SDimitry Andric //
130b57cec5SDimitry Andric //===----------------------------------------------------------------------===//
140b57cec5SDimitry Andric 
150b57cec5SDimitry Andric #define DOUBLE_PRECISION
160b57cec5SDimitry Andric #include "fp_lib.h"
170b57cec5SDimitry Andric 
180b57cec5SDimitry Andric #include "int_lib.h"
190b57cec5SDimitry Andric 
20*5ffd83dbSDimitry Andric COMPILER_RT_ABI fp_t __floatsidf(si_int a) {
210b57cec5SDimitry Andric 
220b57cec5SDimitry Andric   const int aWidth = sizeof a * CHAR_BIT;
230b57cec5SDimitry Andric 
240b57cec5SDimitry Andric   // Handle zero as a special case to protect clz
250b57cec5SDimitry Andric   if (a == 0)
260b57cec5SDimitry Andric     return fromRep(0);
270b57cec5SDimitry Andric 
280b57cec5SDimitry Andric   // All other cases begin by extracting the sign and absolute value of a
290b57cec5SDimitry Andric   rep_t sign = 0;
300b57cec5SDimitry Andric   if (a < 0) {
310b57cec5SDimitry Andric     sign = signBit;
320b57cec5SDimitry Andric     a = -a;
330b57cec5SDimitry Andric   }
340b57cec5SDimitry Andric 
350b57cec5SDimitry Andric   // Exponent of (fp_t)a is the width of abs(a).
36*5ffd83dbSDimitry Andric   const int exponent = (aWidth - 1) - clzsi(a);
370b57cec5SDimitry Andric   rep_t result;
380b57cec5SDimitry Andric 
390b57cec5SDimitry Andric   // Shift a into the significand field and clear the implicit bit.  Extra
400b57cec5SDimitry Andric   // cast to unsigned int is necessary to get the correct behavior for
410b57cec5SDimitry Andric   // the input INT_MIN.
420b57cec5SDimitry Andric   const int shift = significandBits - exponent;
43*5ffd83dbSDimitry Andric   result = (rep_t)(su_int)a << shift ^ implicitBit;
440b57cec5SDimitry Andric 
450b57cec5SDimitry Andric   // Insert the exponent
460b57cec5SDimitry Andric   result += (rep_t)(exponent + exponentBias) << significandBits;
470b57cec5SDimitry Andric   // Insert the sign bit and return
480b57cec5SDimitry Andric   return fromRep(result | sign);
490b57cec5SDimitry Andric }
500b57cec5SDimitry Andric 
510b57cec5SDimitry Andric #if defined(__ARM_EABI__)
520b57cec5SDimitry Andric #if defined(COMPILER_RT_ARMHF_TARGET)
53*5ffd83dbSDimitry Andric AEABI_RTABI fp_t __aeabi_i2d(si_int a) { return __floatsidf(a); }
540b57cec5SDimitry Andric #else
550b57cec5SDimitry Andric COMPILER_RT_ALIAS(__floatsidf, __aeabi_i2d)
560b57cec5SDimitry Andric #endif
570b57cec5SDimitry Andric #endif
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