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![Thomas Gleixner](/assets/img/avatar_default.png)
Based on 1 normalized pattern(s): this program is free software you can distribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 51 franklin st fifth floor boston ma 02110 1301 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 33 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Richard Fontana <rfontana@redhat.com> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190531081038.563233189@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
196 lines
4.2 KiB
C
196 lines
4.2 KiB
C
// 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 <linux/compiler.h>
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#include "ieee754sp.h"
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int ieee754sp_class(union ieee754sp x)
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{
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COMPXSP;
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EXPLODEXSP;
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return xc;
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}
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static inline int ieee754sp_isnan(union ieee754sp x)
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{
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return ieee754_class_nan(ieee754sp_class(x));
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}
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static inline int ieee754sp_issnan(union ieee754sp x)
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{
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int qbit;
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assert(ieee754sp_isnan(x));
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qbit = (SPMANT(x) & SP_MBIT(SP_FBITS - 1)) == SP_MBIT(SP_FBITS - 1);
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return ieee754_csr.nan2008 ^ qbit;
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}
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/*
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* Raise the Invalid Operation IEEE 754 exception
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* and convert the signaling NaN supplied to a quiet NaN.
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*/
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union ieee754sp __cold ieee754sp_nanxcpt(union ieee754sp r)
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{
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assert(ieee754sp_issnan(r));
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ieee754_setcx(IEEE754_INVALID_OPERATION);
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if (ieee754_csr.nan2008) {
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SPMANT(r) |= SP_MBIT(SP_FBITS - 1);
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} else {
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SPMANT(r) &= ~SP_MBIT(SP_FBITS - 1);
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if (!ieee754sp_isnan(r))
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SPMANT(r) |= SP_MBIT(SP_FBITS - 2);
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}
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return r;
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}
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static unsigned int ieee754sp_get_rounding(int sn, unsigned int xm)
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{
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/* inexact must round of 3 bits
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*/
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if (xm & (SP_MBIT(3) - 1)) {
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switch (ieee754_csr.rm) {
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case FPU_CSR_RZ:
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break;
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case FPU_CSR_RN:
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xm += 0x3 + ((xm >> 3) & 1);
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/* xm += (xm&0x8)?0x4:0x3 */
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break;
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case FPU_CSR_RU: /* toward +Infinity */
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if (!sn) /* ?? */
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xm += 0x8;
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break;
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case FPU_CSR_RD: /* toward -Infinity */
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if (sn) /* ?? */
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xm += 0x8;
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break;
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}
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}
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return xm;
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}
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/* generate a normal/denormal number with over,under handling
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* sn is sign
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* xe is an unbiased exponent
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* xm is 3bit extended precision value.
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*/
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union ieee754sp ieee754sp_format(int sn, int xe, unsigned int xm)
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{
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assert(xm); /* we don't gen exact zeros (probably should) */
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assert((xm >> (SP_FBITS + 1 + 3)) == 0); /* no excess */
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assert(xm & (SP_HIDDEN_BIT << 3));
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if (xe < SP_EMIN) {
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/* strip lower bits */
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int es = SP_EMIN - xe;
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if (ieee754_csr.nod) {
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ieee754_setcx(IEEE754_UNDERFLOW);
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ieee754_setcx(IEEE754_INEXACT);
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switch(ieee754_csr.rm) {
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case FPU_CSR_RN:
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case FPU_CSR_RZ:
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return ieee754sp_zero(sn);
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case FPU_CSR_RU: /* toward +Infinity */
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if (sn == 0)
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return ieee754sp_min(0);
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else
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return ieee754sp_zero(1);
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case FPU_CSR_RD: /* toward -Infinity */
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if (sn == 0)
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return ieee754sp_zero(0);
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else
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return ieee754sp_min(1);
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}
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}
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if (xe == SP_EMIN - 1 &&
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ieee754sp_get_rounding(sn, xm) >> (SP_FBITS + 1 + 3))
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{
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/* Not tiny after rounding */
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ieee754_setcx(IEEE754_INEXACT);
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xm = ieee754sp_get_rounding(sn, xm);
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xm >>= 1;
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/* Clear grs bits */
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xm &= ~(SP_MBIT(3) - 1);
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xe++;
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} else {
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/* sticky right shift es bits
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*/
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xm = XSPSRS(xm, es);
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xe += es;
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assert((xm & (SP_HIDDEN_BIT << 3)) == 0);
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assert(xe == SP_EMIN);
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}
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}
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if (xm & (SP_MBIT(3) - 1)) {
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ieee754_setcx(IEEE754_INEXACT);
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if ((xm & (SP_HIDDEN_BIT << 3)) == 0) {
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ieee754_setcx(IEEE754_UNDERFLOW);
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}
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/* inexact must round of 3 bits
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*/
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xm = ieee754sp_get_rounding(sn, xm);
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/* adjust exponent for rounding add overflowing
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*/
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if (xm >> (SP_FBITS + 1 + 3)) {
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/* add causes mantissa overflow */
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xm >>= 1;
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xe++;
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}
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}
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/* strip grs bits */
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xm >>= 3;
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assert((xm >> (SP_FBITS + 1)) == 0); /* no excess */
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assert(xe >= SP_EMIN);
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if (xe > SP_EMAX) {
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ieee754_setcx(IEEE754_OVERFLOW);
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ieee754_setcx(IEEE754_INEXACT);
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/* -O can be table indexed by (rm,sn) */
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switch (ieee754_csr.rm) {
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case FPU_CSR_RN:
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return ieee754sp_inf(sn);
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case FPU_CSR_RZ:
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return ieee754sp_max(sn);
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case FPU_CSR_RU: /* toward +Infinity */
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if (sn == 0)
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return ieee754sp_inf(0);
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else
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return ieee754sp_max(1);
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case FPU_CSR_RD: /* toward -Infinity */
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if (sn == 0)
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return ieee754sp_max(0);
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else
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return ieee754sp_inf(1);
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}
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}
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/* gen norm/denorm/zero */
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if ((xm & SP_HIDDEN_BIT) == 0) {
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/* we underflow (tiny/zero) */
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assert(xe == SP_EMIN);
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if (ieee754_csr.mx & IEEE754_UNDERFLOW)
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ieee754_setcx(IEEE754_UNDERFLOW);
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return buildsp(sn, SP_EMIN - 1 + SP_EBIAS, xm);
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} else {
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assert((xm >> (SP_FBITS + 1)) == 0); /* no excess */
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assert(xm & SP_HIDDEN_BIT);
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return buildsp(sn, xe + SP_EBIAS, xm & ~SP_HIDDEN_BIT);
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}
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}
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