mirror of https://github.com/ksherlock/mpw.git
106 lines
1.6 KiB
C++
106 lines
1.6 KiB
C++
#include "fpinfo.h"
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#include <machine/endian.h>
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static_assert(sizeof(float) == 4, "Unexpected float size");
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static_assert(sizeof(double) == 8, "Unexpected double size");
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static_assert(sizeof(long double) == 8 || sizeof(long double) == 16, "Unexpected long double size");
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void fpinfo::init(float *f)
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{
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union split {
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float f;
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uint32_t i;
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};
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uint32_t i = ((split *)f)->i;
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sign = i >> 31;
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one = 1;
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exp = (i >> 23) & ((1 << 8) - 1);
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sig = i & ((1 << 24) - 1);
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if (exp == 255) {
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if (sig == 0) inf = true;
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else nan = true;
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return;
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}
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if (exp == 0) {
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// 0 or denormalized.
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one = 0;
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exp = -126;
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return;
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}
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exp -= 127; // bias
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}
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void fpinfo::init(double *d)
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{
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union split {
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double d;
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uint64_t i;
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};
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uint64_t i = ((split *)d)->i;
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sign = i >> 63;
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one = 1;
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exp = (i >> 52) & ((1 << 11) - 1);
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sig = i & ((UINT64_C(1) << 53) - 1);
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if (exp == 2047) {
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if (sig == 0) inf = true;
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else nan = true;
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return;
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}
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if (exp == 0) {
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// 0 or denormalized.
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one = 0;
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exp = -1022;
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return;
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}
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exp -= 1023; // bias
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}
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void fpinfo::init(long double *ld)
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{
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union split {
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long double ld;
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uint64_t i[2];
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};
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uint64_t i;
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uint32_t sexp;
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// this needs to be verified.
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#if BYTE_ORDER == LITTLE_ENDIAN
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i = ((split *)ld)->i[0];
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sexp = ((split *)ld)->i[1];
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#else
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i = ((split *)ld)->i[1];
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sexp = ((split *)ld)->i[0] & 0xffff;
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#endif
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sign = (sexp >> 15) & 0x01;
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exp = sexp & ((1 << 15) - 1);
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one = i >> 63;
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sig = i & ((UINT64_C(1) << 63) - 1);
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if (exp == 32767) {
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if (sig == 0) inf = true;
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else nan = true;
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return;
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}
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//
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exp -= 16383;
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} |