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143 lines
3.4 KiB
143 lines
3.4 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* IEEE754 floating point arithmetic |
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* double precision: common utilities |
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*/ |
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/* |
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* MIPS floating point support |
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* Copyright (C) 1994-2000 Algorithmics Ltd. |
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*/ |
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#include "ieee754dp.h" |
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union ieee754dp ieee754dp_div(union ieee754dp x, union ieee754dp y) |
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{ |
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u64 rm; |
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int re; |
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u64 bm; |
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COMPXDP; |
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COMPYDP; |
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EXPLODEXDP; |
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EXPLODEYDP; |
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ieee754_clearcx(); |
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FLUSHXDP; |
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FLUSHYDP; |
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switch (CLPAIR(xc, yc)) { |
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN): |
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): |
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): |
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): |
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): |
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return ieee754dp_nanxcpt(y); |
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): |
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): |
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO): |
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM): |
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM): |
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case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF): |
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return ieee754dp_nanxcpt(x); |
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN): |
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN): |
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN): |
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN): |
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return y; |
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN): |
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO): |
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM): |
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM): |
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case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF): |
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return x; |
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/* |
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* Infinity handling |
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*/ |
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): |
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ieee754_setcx(IEEE754_INVALID_OPERATION); |
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return ieee754dp_indef(); |
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): |
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): |
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): |
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return ieee754dp_zero(xs ^ ys); |
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): |
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): |
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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): |
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return ieee754dp_inf(xs ^ ys); |
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/* |
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* Zero handling |
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*/ |
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): |
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ieee754_setcx(IEEE754_INVALID_OPERATION); |
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return ieee754dp_indef(); |
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): |
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): |
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ieee754_setcx(IEEE754_ZERO_DIVIDE); |
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return ieee754dp_inf(xs ^ ys); |
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): |
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): |
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return ieee754dp_zero(xs == ys ? 0 : 1); |
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): |
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DPDNORMX; |
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fallthrough; |
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): |
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DPDNORMY; |
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break; |
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): |
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DPDNORMX; |
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break; |
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): |
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break; |
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} |
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assert(xm & DP_HIDDEN_BIT); |
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assert(ym & DP_HIDDEN_BIT); |
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/* provide rounding space */ |
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xm <<= 3; |
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ym <<= 3; |
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/* now the dirty work */ |
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rm = 0; |
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re = xe - ye; |
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for (bm = DP_MBIT(DP_FBITS + 2); bm; bm >>= 1) { |
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if (xm >= ym) { |
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xm -= ym; |
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rm |= bm; |
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if (xm == 0) |
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break; |
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} |
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xm <<= 1; |
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} |
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rm <<= 1; |
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if (xm) |
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rm |= 1; /* have remainder, set sticky */ |
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assert(rm); |
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/* |
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* Normalise rm to rounding precision ? |
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*/ |
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while ((rm >> (DP_FBITS + 3)) == 0) { |
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rm <<= 1; |
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re--; |
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} |
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return ieee754dp_format(xs == ys ? 0 : 1, re, rm); |
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}
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