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159 lines
3.8 KiB
159 lines
3.8 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_mul(union ieee754dp x, union ieee754dp y) |
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{ |
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int re; |
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int rs; |
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u64 rm; |
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unsigned int lxm; |
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unsigned int hxm; |
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unsigned int lym; |
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unsigned int hym; |
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u64 lrm; |
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u64 hrm; |
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u64 t; |
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u64 at; |
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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_ZERO): |
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case CLPAIR(IEEE754_CLASS_ZERO, 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_DNORM, IEEE754_CLASS_INF): |
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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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case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): |
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return ieee754dp_inf(xs ^ ys); |
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case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): |
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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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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): |
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): |
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return ieee754dp_zero(xs ^ ys); |
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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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/* rm = xm * ym, re = xe+ye basically */ |
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assert(xm & DP_HIDDEN_BIT); |
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assert(ym & DP_HIDDEN_BIT); |
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re = xe + ye; |
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rs = xs ^ ys; |
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/* shunt to top of word */ |
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xm <<= 64 - (DP_FBITS + 1); |
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ym <<= 64 - (DP_FBITS + 1); |
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/* |
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* Multiply 64 bits xm, ym to give high 64 bits rm with stickness. |
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*/ |
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lxm = xm; |
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hxm = xm >> 32; |
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lym = ym; |
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hym = ym >> 32; |
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lrm = DPXMULT(lxm, lym); |
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hrm = DPXMULT(hxm, hym); |
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t = DPXMULT(lxm, hym); |
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at = lrm + (t << 32); |
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hrm += at < lrm; |
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lrm = at; |
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hrm = hrm + (t >> 32); |
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t = DPXMULT(hxm, lym); |
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at = lrm + (t << 32); |
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hrm += at < lrm; |
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lrm = at; |
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hrm = hrm + (t >> 32); |
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rm = hrm | (lrm != 0); |
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/* |
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* Sticky shift down to normal rounding precision. |
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*/ |
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if ((s64) rm < 0) { |
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rm = (rm >> (64 - (DP_FBITS + 1 + 3))) | |
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((rm << (DP_FBITS + 1 + 3)) != 0); |
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re++; |
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} else { |
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rm = (rm >> (64 - (DP_FBITS + 1 + 3 + 1))) | |
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((rm << (DP_FBITS + 1 + 3 + 1)) != 0); |
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} |
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assert(rm & (DP_HIDDEN_BIT << 3)); |
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return ieee754dp_format(rs, re, rm); |
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}
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