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improved rounding

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This commit is contained in:
ceriel 1989-08-09 14:37:07 +00:00
parent d277946286
commit 98f011552e
1 changed files with 24 additions and 9 deletions
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33
mach/con_float
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@ -77,6 +77,16 @@ float_cst(str, sz, buf)
e.flt_exp += 127; e.flt_exp += 127;
if (e.flt_mantissa.flt_h_32 == 0) e.flt_exp = 0; if (e.flt_mantissa.flt_h_32 == 0) e.flt_exp = 0;
#ifdef IEEEFLOAT #ifdef IEEEFLOAT
if (e.flt_mantissa.flt_l_32 & 0x80) {
/* rounding */
if ((e.flt_mantissa.flt_h_32 & 0xffffff00) == 0xffffff00) {
e.flt_exp++;
e.flt_mantissa.flt_h_32 = 0x80000000;
}
else {
e.flt_mantissa.flt_h_32 += 0x80;
}
}
if (e.flt_exp >= 255) { if (e.flt_exp >= 255) {
overflow = 1; overflow = 1;
e.flt_exp = 255; e.flt_exp = 255;
@ -111,6 +121,19 @@ float_cst(str, sz, buf)
else { else {
e.flt_exp += 1023; e.flt_exp += 1023;
if (e.flt_mantissa.flt_h_32 == 0) e.flt_exp = 0; if (e.flt_mantissa.flt_h_32 == 0) e.flt_exp = 0;
if (e.flt_mantissa.flt_l_32 & 0x400) {
/* rounding */
if ((e.flt_mantissa.flt_l_32 & 0xfffff800) == 0xfffff800) {
e.flt_mantissa.flt_l_32 = 0;
if ((e.flt_mantissa.flt_h_32 += 1) == 0) {
e.flt_exp++;
e.flt_mantissa.flt_h_32 = 0x80000000;
}
}
else {
e.flt_mantissa.flt_l_32 += 0x400;
}
}
if (e.flt_exp >= 2047) { if (e.flt_exp >= 2047) {
overflow = 1; overflow = 1;
e.flt_exp = 2047; e.flt_exp = 2047;
@ -134,15 +157,7 @@ float_cst(str, sz, buf)
flt_b64_sft(&(e.flt_mantissa), -53); flt_b64_sft(&(e.flt_mantissa), -53);
} }
#endif #endif
i = sz-1; if (overflow) {
if (! overflow && (e.flt_mantissa.flt_h_32 & 0x80000000)) for (; i>=0; i--) {
if ((buf[i] &0377) != 0377) {
buf[i]++;
break;
}
else buf[i] = 0;
}
if (overflow || i < 0) {
return 2; return 2;
} }
return 0; return 0;