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154 lines
3.8 KiB
154 lines
3.8 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* IEEE754 floating point arithmetic |
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* single precision |
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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 "ieee754sp.h" |
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union ieee754sp ieee754sp_mul(union ieee754sp x, union ieee754sp y) |
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{ |
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int re; |
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int rs; |
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unsigned int rm; |
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unsigned short lxm; |
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unsigned short hxm; |
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unsigned short lym; |
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unsigned short hym; |
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unsigned int lrm; |
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unsigned int hrm; |
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unsigned int t; |
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unsigned int at; |
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COMPXSP; |
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COMPYSP; |
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EXPLODEXSP; |
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EXPLODEYSP; |
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ieee754_clearcx(); |
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FLUSHXSP; |
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FLUSHYSP; |
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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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_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 ieee754sp_zero(xs ^ ys); |
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): |
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SPDNORMX; |
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fallthrough; |
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case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): |
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SPDNORMY; |
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break; |
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case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): |
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SPDNORMX; |
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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 & SP_HIDDEN_BIT); |
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assert(ym & SP_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 <<= 32 - (SP_FBITS + 1); |
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ym <<= 32 - (SP_FBITS + 1); |
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/* |
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* Multiply 32 bits xm, ym to give high 32 bits rm with stickness. |
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*/ |
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lxm = xm & 0xffff; |
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hxm = xm >> 16; |
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lym = ym & 0xffff; |
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hym = ym >> 16; |
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lrm = lxm * lym; /* 16 * 16 => 32 */ |
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hrm = hxm * hym; /* 16 * 16 => 32 */ |
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t = lxm * hym; /* 16 * 16 => 32 */ |
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at = lrm + (t << 16); |
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hrm += at < lrm; |
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lrm = at; |
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hrm = hrm + (t >> 16); |
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t = hxm * lym; /* 16 * 16 => 32 */ |
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at = lrm + (t << 16); |
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hrm += at < lrm; |
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lrm = at; |
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hrm = hrm + (t >> 16); |
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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 ((int) rm < 0) { |
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rm = (rm >> (32 - (SP_FBITS + 1 + 3))) | |
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((rm << (SP_FBITS + 1 + 3)) != 0); |
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re++; |
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} else { |
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rm = (rm >> (32 - (SP_FBITS + 1 + 3 + 1))) | |
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((rm << (SP_FBITS + 1 + 3 + 1)) != 0); |
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} |
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assert(rm & (SP_HIDDEN_BIT << 3)); |
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return ieee754sp_format(rs, re, rm); |
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}
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