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math: use float_t and double_t in scalbnf and scalbn

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remove STRICT_ASSIGN (c99 semantics is assumed) and use the conventional
union to prepare the scaling factor (so libm.h is no longer needed)
This commit is contained in:
Szabolcs Nagy
2013-09-04 15:52:54 +00:00
parent 34660d73bd
commit 2eaed464e2
2 changed files with 20 additions and 16 deletions
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18
src/math/scalbn.c
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@ -1,29 +1,31 @@
#include "libm.h" #include <math.h>
#include <stdint.h>
double scalbn(double x, int n) double scalbn(double x, int n)
{ {
double scale; union {double f; uint64_t i;} u;
double_t y = x;
if (n > 1023) { if (n > 1023) {
x *= 0x1p1023; y *= 0x1p1023;
n -= 1023; n -= 1023;
if (n > 1023) { if (n > 1023) {
x *= 0x1p1023; y *= 0x1p1023;
n -= 1023; n -= 1023;
if (n > 1023) if (n > 1023)
n = 1023; n = 1023;
} }
} else if (n < -1022) { } else if (n < -1022) {
x *= 0x1p-1022; y *= 0x1p-1022;
n += 1022; n += 1022;
if (n < -1022) { if (n < -1022) {
x *= 0x1p-1022; y *= 0x1p-1022;
n += 1022; n += 1022;
if (n < -1022) if (n < -1022)
n = -1022; n = -1022;
} }
} }
INSERT_WORDS(scale, (uint32_t)(0x3ff+n)<<20, 0); u.i = (uint64_t)(0x3ff+n)<<52;
STRICT_ASSIGN(double, x, x * scale); x = y * u.f;
return x; return x;
} }

18
src/math/scalbnf.c
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@ -1,29 +1,31 @@
#include "libm.h" #include <math.h>
#include <stdint.h>
float scalbnf(float x, int n) float scalbnf(float x, int n)
{ {
float scale; union {float f; uint32_t i;} u;
float_t y = x;
if (n > 127) { if (n > 127) {
x *= 0x1p127f; y *= 0x1p127f;
n -= 127; n -= 127;
if (n > 127) { if (n > 127) {
x *= 0x1p127f; y *= 0x1p127f;
n -= 127; n -= 127;
if (n > 127) if (n > 127)
n = 127; n = 127;
} }
} else if (n < -126) { } else if (n < -126) {
x *= 0x1p-126f; y *= 0x1p-126f;
n += 126; n += 126;
if (n < -126) { if (n < -126) {
x *= 0x1p-126f; y *= 0x1p-126f;
n += 126; n += 126;
if (n < -126) if (n < -126)
n = -126; n = -126;
} }
} }
SET_FLOAT_WORD(scale, (uint32_t)(0x7f+n)<<23); u.i = (uint32_t)(0x7f+n)<<23;
STRICT_ASSIGN(float, x, x * scale); x = y * u.f;
return x; return x;
} }