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Date: Thu, 21 Apr 2016 14:04:49 +0100
From: Paul Burton <paul.burton@...tec.com>
To: <linux-mips@...ux-mips.org>, Ralf Baechle <ralf@...ux-mips.org>
CC: Paul Burton <paul.burton@...tec.com>,
Markos Chandras <markos.chandras@...tec.com>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH 05/11] MIPS: math-emu: Unify ieee754sp_m{add,sub}f
The code for emulating MIPSr6 madd.s & msub.s instructions has
previously been implemented as 2 different functions, namely
ieee754sp_maddf & ieee754sp_msubf. The difference in behaviour of these
2 instructions is merely the sign of the product, so we can easily share
the code implementing them. Do this for the single precision variant,
removing the original ieee754sp_msubf in favor of reusing the code from
ieee754sp_maddf.
Signed-off-by: Paul Burton <paul.burton@...tec.com>
---
arch/mips/math-emu/Makefile | 2 +-
arch/mips/math-emu/sp_maddf.c | 22 +++-
arch/mips/math-emu/sp_msubf.c | 258 ------------------------------------------
3 files changed, 21 insertions(+), 261 deletions(-)
delete mode 100644 arch/mips/math-emu/sp_msubf.c
diff --git a/arch/mips/math-emu/Makefile b/arch/mips/math-emu/Makefile
index a19641d..3389aff 100644
--- a/arch/mips/math-emu/Makefile
+++ b/arch/mips/math-emu/Makefile
@@ -6,7 +6,7 @@ obj-y += cp1emu.o ieee754dp.o ieee754sp.o ieee754.o \
dp_div.o dp_mul.o dp_sub.o dp_add.o dp_fsp.o dp_cmp.o dp_simple.o \
dp_tint.o dp_fint.o dp_maddf.o dp_msubf.o dp_2008class.o dp_fmin.o dp_fmax.o \
sp_div.o sp_mul.o sp_sub.o sp_add.o sp_fdp.o sp_cmp.o sp_simple.o \
- sp_tint.o sp_fint.o sp_maddf.o sp_msubf.o sp_2008class.o sp_fmin.o sp_fmax.o \
+ sp_tint.o sp_fint.o sp_maddf.o sp_2008class.o sp_fmin.o sp_fmax.o \
dsemul.o
lib-y += ieee754d.o \
diff --git a/arch/mips/math-emu/sp_maddf.c b/arch/mips/math-emu/sp_maddf.c
index dd1dd83..93b7132 100644
--- a/arch/mips/math-emu/sp_maddf.c
+++ b/arch/mips/math-emu/sp_maddf.c
@@ -14,8 +14,12 @@
#include "ieee754sp.h"
-union ieee754sp ieee754sp_maddf(union ieee754sp z, union ieee754sp x,
- union ieee754sp y)
+enum maddf_flags {
+ maddf_negate_product = 1 << 0,
+};
+
+static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x,
+ union ieee754sp y, enum maddf_flags flags)
{
int re;
int rs;
@@ -154,6 +158,8 @@ union ieee754sp ieee754sp_maddf(union ieee754sp z, union ieee754sp x,
re = xe + ye;
rs = xs ^ ys;
+ if (flags & maddf_negate_product)
+ rs ^= 1;
/* shunt to top of word */
xm <<= 32 - (SP_FBITS + 1);
@@ -253,3 +259,15 @@ union ieee754sp ieee754sp_maddf(union ieee754sp z, union ieee754sp x,
}
return ieee754sp_format(zs, ze, zm);
}
+
+union ieee754sp ieee754sp_maddf(union ieee754sp z, union ieee754sp x,
+ union ieee754sp y)
+{
+ return _sp_maddf(z, x, y, 0);
+}
+
+union ieee754sp ieee754sp_msubf(union ieee754sp z, union ieee754sp x,
+ union ieee754sp y)
+{
+ return _sp_maddf(z, x, y, maddf_negate_product);
+}
diff --git a/arch/mips/math-emu/sp_msubf.c b/arch/mips/math-emu/sp_msubf.c
deleted file mode 100644
index 81c38b980..0000000
--- a/arch/mips/math-emu/sp_msubf.c
+++ /dev/null
@@ -1,258 +0,0 @@
-/*
- * IEEE754 floating point arithmetic
- * single precision: MSUB.f (Fused Multiply Subtract)
- * MSUBF.fmt: FPR[fd] = FPR[fd] - (FPR[fs] x FPR[ft])
- *
- * MIPS floating point support
- * Copyright (C) 2015 Imagination Technologies, Ltd.
- * Author: Markos Chandras <markos.chandras@...tec.com>
- *
- * This program is free software; you can distribute it and/or modify it
- * under the terms of the GNU General Public License as published by the
- * Free Software Foundation; version 2 of the License.
- */
-
-#include "ieee754sp.h"
-
-union ieee754sp ieee754sp_msubf(union ieee754sp z, union ieee754sp x,
- union ieee754sp y)
-{
- int re;
- int rs;
- unsigned rm;
- unsigned short lxm;
- unsigned short hxm;
- unsigned short lym;
- unsigned short hym;
- unsigned lrm;
- unsigned hrm;
- unsigned t;
- unsigned at;
- int s;
-
- COMPXSP;
- COMPYSP;
- u32 zm; int ze; int zs __maybe_unused; int zc;
-
- EXPLODEXSP;
- EXPLODEYSP;
- EXPLODESP(z, zc, zs, ze, zm)
-
- FLUSHXSP;
- FLUSHYSP;
- FLUSHSP(z, zc, zs, ze, zm);
-
- ieee754_clearcx();
-
- switch (zc) {
- case IEEE754_CLASS_SNAN:
- ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754sp_nanxcpt(z);
- case IEEE754_CLASS_DNORM:
- SPDNORMx(zm, ze);
- /* QNAN is handled separately below */
- }
-
- switch (CLPAIR(xc, yc)) {
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
- return ieee754sp_nanxcpt(y);
-
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
- return ieee754sp_nanxcpt(x);
-
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
- return y;
-
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
- return x;
-
- /*
- * Infinity handling
- */
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
- if (zc == IEEE754_CLASS_QNAN)
- return z;
- ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754sp_indef();
-
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
- if (zc == IEEE754_CLASS_QNAN)
- return z;
- return ieee754sp_inf(xs ^ ys);
-
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
- if (zc == IEEE754_CLASS_INF)
- return ieee754sp_inf(zs);
- /* Multiplication is 0 so just return z */
- return z;
-
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
- SPDNORMX;
-
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
- if (zc == IEEE754_CLASS_QNAN)
- return z;
- else if (zc == IEEE754_CLASS_INF)
- return ieee754sp_inf(zs);
- SPDNORMY;
- break;
-
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
- if (zc == IEEE754_CLASS_QNAN)
- return z;
- else if (zc == IEEE754_CLASS_INF)
- return ieee754sp_inf(zs);
- SPDNORMX;
- break;
-
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
- if (zc == IEEE754_CLASS_QNAN)
- return z;
- else if (zc == IEEE754_CLASS_INF)
- return ieee754sp_inf(zs);
- /* fall through to real compuation */
- }
-
- /* Finally get to do some computation */
-
- /*
- * Do the multiplication bit first
- *
- * rm = xm * ym, re = xe + ye basically
- *
- * At this point xm and ym should have been normalized.
- */
-
- /* rm = xm * ym, re = xe+ye basically */
- assert(xm & SP_HIDDEN_BIT);
- assert(ym & SP_HIDDEN_BIT);
-
- re = xe + ye;
- rs = xs ^ ys;
-
- /* shunt to top of word */
- xm <<= 32 - (SP_FBITS + 1);
- ym <<= 32 - (SP_FBITS + 1);
-
- /*
- * Multiply 32 bits xm, ym to give high 32 bits rm with stickness.
- */
- lxm = xm & 0xffff;
- hxm = xm >> 16;
- lym = ym & 0xffff;
- hym = ym >> 16;
-
- lrm = lxm * lym; /* 16 * 16 => 32 */
- hrm = hxm * hym; /* 16 * 16 => 32 */
-
- t = lxm * hym; /* 16 * 16 => 32 */
- at = lrm + (t << 16);
- hrm += at < lrm;
- lrm = at;
- hrm = hrm + (t >> 16);
-
- t = hxm * lym; /* 16 * 16 => 32 */
- at = lrm + (t << 16);
- hrm += at < lrm;
- lrm = at;
- hrm = hrm + (t >> 16);
-
- rm = hrm | (lrm != 0);
-
- /*
- * Sticky shift down to normal rounding precision.
- */
- if ((int) rm < 0) {
- rm = (rm >> (32 - (SP_FBITS + 1 + 3))) |
- ((rm << (SP_FBITS + 1 + 3)) != 0);
- re++;
- } else {
- rm = (rm >> (32 - (SP_FBITS + 1 + 3 + 1))) |
- ((rm << (SP_FBITS + 1 + 3 + 1)) != 0);
- }
- assert(rm & (SP_HIDDEN_BIT << 3));
-
- /* And now the subtraction */
-
- /* Flip sign of r and handle as add */
- rs ^= 1;
-
- assert(zm & SP_HIDDEN_BIT);
-
- /*
- * Provide guard,round and stick bit space.
- */
- zm <<= 3;
-
- if (ze > re) {
- /*
- * Have to shift y fraction right to align.
- */
- s = ze - re;
- SPXSRSYn(s);
- } else if (re > ze) {
- /*
- * Have to shift x fraction right to align.
- */
- s = re - ze;
- SPXSRSYn(s);
- }
- assert(ze == re);
- assert(ze <= SP_EMAX);
-
- if (zs == rs) {
- /*
- * Generate 28 bit result of adding two 27 bit numbers
- * leaving result in zm, zs and ze.
- */
- zm = zm + rm;
-
- if (zm >> (SP_FBITS + 1 + 3)) { /* carry out */
- SPXSRSX1(); /* shift preserving sticky */
- }
- } else {
- if (zm >= rm) {
- zm = zm - rm;
- } else {
- zm = rm - zm;
- zs = rs;
- }
- if (zm == 0)
- return ieee754sp_zero(ieee754_csr.rm == FPU_CSR_RD);
-
- /*
- * Normalize in extended single precision
- */
- while ((zm >> (SP_MBITS + 3)) == 0) {
- zm <<= 1;
- ze--;
- }
-
- }
- return ieee754sp_format(zs, ze, zm);
-}
--
2.8.0
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