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author | Xavier Leroy <xavier.leroy@inria.fr> | 2015-02-14 11:08:57 +0100 |
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committer | Xavier Leroy <xavier.leroy@inria.fr> | 2015-02-14 11:08:57 +0100 |
commit | fe57280950fc20b2d1650a022033484b152ae51d (patch) | |
tree | 8ac95e2b680344fdff5ff475646999270d5361e4 /runtime/c/i64_dtou.c | |
parent | f2b1c25aa56a27836652aef3feeee0856c04235c (diff) | |
download | compcert-fe57280950fc20b2d1650a022033484b152ae51d.tar.gz compcert-fe57280950fc20b2d1650a022033484b152ae51d.zip |
C reference implementation of the int64 helper functions.
In test_int64.c: don't test FP->int64 conversions when the FP argument is out of range.
Diffstat (limited to 'runtime/c/i64_dtou.c')
-rw-r--r-- | runtime/c/i64_dtou.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/runtime/c/i64_dtou.c b/runtime/c/i64_dtou.c new file mode 100644 index 00000000..c5f9df4d --- /dev/null +++ b/runtime/c/i64_dtou.c @@ -0,0 +1,69 @@ +/***************************************************************** + * + * The Compcert verified compiler + * + * Xavier Leroy, INRIA Paris-Rocquencourt + * + * Copyright (c) 2013 Institut National de Recherche en Informatique et + * en Automatique. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * * Neither the name of the <organization> nor the + * names of its contributors may be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT + * HOLDER> BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + **********************************************************************/ + +/* Helper functions for 64-bit integer arithmetic. Reference C implementation */ + +#include "i64.h" + +/* Conversion float64 -> unsigned int64 */ + +unsigned long long __i64_dtou(double d) +{ + /* Extract bits of d's representation */ + union { double d; unsigned long long i; } buf; + buf.d = d; + unsigned int h = buf.i >> 32; + /* Negative FP numbers convert to 0 */ + if ((int) h < 0) return 0ULL; + /* Extract unbiased exponent */ + int e = ((h & 0x7FF00000) >> 20) - (1023 + 52); + /* Check range of exponent */ + if (e < -52) { + /* d is less than 1.0 */ + return 0ULL; + } + if (e >= 64 - 52) { + /* d is greater or equal to 2^64 */ + return 0xFFFFFFFFFFFFFFFFULL; /* max unsigned long long */ + } + /* Extract true mantissa */ + unsigned long long m = + (buf.i & ~0xFFF0000000000000LL) | 0x0010000000000000LL; + /* Shift it appropriately */ + if (e >= 0) + return __i64_shl(m, e); + else + return __i64_shr(m, -e); + +} |