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Date: Thu, 21 Apr 2016 14:04:50 +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 06/11] MIPS: math-emu: Unify ieee754dp_m{add,sub}f
The code for emulating MIPSr6 madd.d & msub.d instructions has
previously been implemented as 2 different functions, namely
ieee754dp_maddf & ieee754dp_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 double precision variant,
removing the original ieee754dp_msubf in favor of reusing the code from
ieee754dp_maddf.
Signed-off-by: Paul Burton <paul.burton@...tec.com>
---
arch/mips/math-emu/Makefile | 2 +-
arch/mips/math-emu/dp_maddf.c | 22 +++-
arch/mips/math-emu/dp_msubf.c | 269 ------------------------------------------
3 files changed, 21 insertions(+), 272 deletions(-)
delete mode 100644 arch/mips/math-emu/dp_msubf.c
diff --git a/arch/mips/math-emu/Makefile b/arch/mips/math-emu/Makefile
index 3389aff..e9bbc2a 100644
--- a/arch/mips/math-emu/Makefile
+++ b/arch/mips/math-emu/Makefile
@@ -4,7 +4,7 @@
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 \
+ dp_tint.o dp_fint.o dp_maddf.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_2008class.o sp_fmin.o sp_fmax.o \
dsemul.o
diff --git a/arch/mips/math-emu/dp_maddf.c b/arch/mips/math-emu/dp_maddf.c
index 119eda9..d5e0fb1 100644
--- a/arch/mips/math-emu/dp_maddf.c
+++ b/arch/mips/math-emu/dp_maddf.c
@@ -14,8 +14,12 @@
#include "ieee754dp.h"
-union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
- union ieee754dp y)
+enum maddf_flags {
+ maddf_negate_product = 1 << 0,
+};
+
+static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
+ union ieee754dp y, enum maddf_flags flags)
{
int re;
int rs;
@@ -154,6 +158,8 @@ union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
re = xe + ye;
rs = xs ^ ys;
+ if (flags & maddf_negate_product)
+ rs ^= 1;
/* shunt to top of word */
xm <<= 64 - (DP_FBITS + 1);
@@ -263,3 +269,15 @@ union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
return ieee754dp_format(zs, ze, zm);
}
+
+union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
+ union ieee754dp y)
+{
+ return _dp_maddf(z, x, y, 0);
+}
+
+union ieee754dp ieee754dp_msubf(union ieee754dp z, union ieee754dp x,
+ union ieee754dp y)
+{
+ return _dp_maddf(z, x, y, maddf_negate_product);
+}
diff --git a/arch/mips/math-emu/dp_msubf.c b/arch/mips/math-emu/dp_msubf.c
deleted file mode 100644
index 1224126..0000000
--- a/arch/mips/math-emu/dp_msubf.c
+++ /dev/null
@@ -1,269 +0,0 @@
-/*
- * IEEE754 floating point arithmetic
- * double 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 "ieee754dp.h"
-
-union ieee754dp ieee754dp_msubf(union ieee754dp z, union ieee754dp x,
- union ieee754dp y)
-{
- int re;
- int rs;
- u64 rm;
- unsigned lxm;
- unsigned hxm;
- unsigned lym;
- unsigned hym;
- u64 lrm;
- u64 hrm;
- u64 t;
- u64 at;
- int s;
-
- COMPXDP;
- COMPYDP;
-
- u64 zm; int ze; int zs __maybe_unused; int zc;
-
- EXPLODEXDP;
- EXPLODEYDP;
- EXPLODEDP(z, zc, zs, ze, zm)
-
- FLUSHXDP;
- FLUSHYDP;
- FLUSHDP(z, zc, zs, ze, zm);
-
- ieee754_clearcx();
-
- switch (zc) {
- case IEEE754_CLASS_SNAN:
- ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754dp_nanxcpt(z);
- case IEEE754_CLASS_DNORM:
- DPDNORMx(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 ieee754dp_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 ieee754dp_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 ieee754dp_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 ieee754dp_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 ieee754dp_inf(zs);
- /* Multiplication is 0 so just return z */
- return z;
-
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
- DPDNORMX;
-
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
- if (zc == IEEE754_CLASS_QNAN)
- return z;
- else if (zc == IEEE754_CLASS_INF)
- return ieee754dp_inf(zs);
- DPDNORMY;
- break;
-
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
- if (zc == IEEE754_CLASS_QNAN)
- return z;
- else if (zc == IEEE754_CLASS_INF)
- return ieee754dp_inf(zs);
- DPDNORMX;
- break;
-
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
- if (zc == IEEE754_CLASS_QNAN)
- return z;
- else if (zc == IEEE754_CLASS_INF)
- return ieee754dp_inf(zs);
- /* fall through to real computations */
- }
-
- /* 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.
- */
- assert(xm & DP_HIDDEN_BIT);
- assert(ym & DP_HIDDEN_BIT);
-
- re = xe + ye;
- rs = xs ^ ys;
-
- /* shunt to top of word */
- xm <<= 64 - (DP_FBITS + 1);
- ym <<= 64 - (DP_FBITS + 1);
-
- /*
- * Multiply 32 bits xm, ym to give high 32 bits rm with stickness.
- */
-
- /* 32 * 32 => 64 */
-#define DPXMULT(x, y) ((u64)(x) * (u64)y)
-
- lxm = xm;
- hxm = xm >> 32;
- lym = ym;
- hym = ym >> 32;
-
- lrm = DPXMULT(lxm, lym);
- hrm = DPXMULT(hxm, hym);
-
- t = DPXMULT(lxm, hym);
-
- at = lrm + (t << 32);
- hrm += at < lrm;
- lrm = at;
-
- hrm = hrm + (t >> 32);
-
- t = DPXMULT(hxm, lym);
-
- at = lrm + (t << 32);
- hrm += at < lrm;
- lrm = at;
-
- hrm = hrm + (t >> 32);
-
- rm = hrm | (lrm != 0);
-
- /*
- * Sticky shift down to normal rounding precision.
- */
- if ((s64) rm < 0) {
- rm = (rm >> (64 - (DP_FBITS + 1 + 3))) |
- ((rm << (DP_FBITS + 1 + 3)) != 0);
- re++;
- } else {
- rm = (rm >> (64 - (DP_FBITS + 1 + 3 + 1))) |
- ((rm << (DP_FBITS + 1 + 3 + 1)) != 0);
- }
- assert(rm & (DP_HIDDEN_BIT << 3));
-
- /* And now the subtraction */
-
- /* flip sign of r and handle as add */
- rs ^= 1;
-
- assert(zm & DP_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;
- rm = XDPSRS(rm, s);
- re += s;
- } else if (re > ze) {
- /*
- * Have to shift x fraction right to align.
- */
- s = re - ze;
- zm = XDPSRS(zm, s);
- ze += s;
- }
- assert(ze == re);
- assert(ze <= DP_EMAX);
-
- if (zs == rs) {
- /*
- * Generate 28 bit result of adding two 27 bit numbers
- * leaving result in xm, xs and xe.
- */
- zm = zm + rm;
-
- if (zm >> (DP_FBITS + 1 + 3)) { /* carry out */
- zm = XDPSRS1(zm);
- ze++;
- }
- } else {
- if (zm >= rm) {
- zm = zm - rm;
- } else {
- zm = rm - zm;
- zs = rs;
- }
- if (zm == 0)
- return ieee754dp_zero(ieee754_csr.rm == FPU_CSR_RD);
-
- /*
- * Normalize to rounding precision.
- */
- while ((zm >> (DP_FBITS + 3)) == 0) {
- zm <<= 1;
- ze--;
- }
- }
-
- return ieee754dp_format(zs, ze, zm);
-}
--
2.8.0
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