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target-ppc: Introduce DFP Helper Utilities

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Add a new file (dfp_helper.c) to the PowerPC implementation for Decimal Floating
Point (DFP) emulation.  This first version of the file declares a structure that
will be used by DFP helpers.  It also implements utilities that will initialize
such a structure for either a long (64 bit) DFP instruction or an extended (128
bit, aka "quad") instruction.

Some utility functions are annotated with the unused attribute in order to preserve
build bisection.

Signed-off-by: Tom Musta <tommusta@gmail.com>
[agraf: Add never reached assert on dfp_prepare_rounding_mode()]
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Tom Musta 2014-04-21 15:54:59 -05:00 committed by Alexander Graf
parent 275e35c6c1
commit 7b0c0d66e5
2 changed files with 133 additions and 0 deletions
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1
target-ppc/Makefile.objs
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@ -6,6 +6,7 @@ obj-$(TARGET_PPC64) += mmu-hash64.o arch_dump.o
endif
obj-$(CONFIG_KVM) += kvm.o kvm_ppc.o
obj-$(call lnot,$(CONFIG_KVM)) += kvm-stub.o
obj-y += dfp_helper.o
obj-y += excp_helper.o
obj-y += fpu_helper.o
obj-y += int_helper.o

132
target-ppc/dfp_helper.c Normal file
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@ -0,0 +1,132 @@
/*
* PowerPC Decimal Floating Point (DPF) emulation helpers for QEMU.
*
* Copyright (c) 2014 IBM Corporation.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "cpu.h"
#include "exec/helper-proto.h"
#define DECNUMDIGITS 34
#include "libdecnumber/decContext.h"
#include "libdecnumber/decNumber.h"
#include "libdecnumber/dpd/decimal32.h"
#include "libdecnumber/dpd/decimal64.h"
#include "libdecnumber/dpd/decimal128.h"
#if defined(HOST_WORDS_BIGENDIAN)
#define HI_IDX 0
#define LO_IDX 1
#else
#define HI_IDX 1
#define LO_IDX 0
#endif
struct PPC_DFP {
CPUPPCState *env;
uint64_t t64[2], a64[2], b64[2];
decNumber t, a, b;
decContext context;
uint8_t crbf;
};
static void dfp_prepare_rounding_mode(decContext *context, uint64_t fpscr)
{
enum rounding rnd;
switch ((fpscr >> 32) & 0x7) {
case 0:
rnd = DEC_ROUND_HALF_EVEN;
break;
case 1:
rnd = DEC_ROUND_DOWN;
break;
case 2:
rnd = DEC_ROUND_CEILING;
break;
case 3:
rnd = DEC_ROUND_FLOOR;
break;
case 4:
rnd = DEC_ROUND_HALF_UP;
break;
case 5:
rnd = DEC_ROUND_HALF_DOWN;
break;
case 6:
rnd = DEC_ROUND_UP;
break;
case 7:
rnd = DEC_ROUND_05UP;
break;
default:
g_assert_not_reached();
}
decContextSetRounding(context, rnd);
}
__attribute__ ((unused))
static void dfp_prepare_decimal64(struct PPC_DFP *dfp, uint64_t *a,
uint64_t *b, CPUPPCState *env)
{
decContextDefault(&dfp->context, DEC_INIT_DECIMAL64);
dfp_prepare_rounding_mode(&dfp->context, env->fpscr);
dfp->env = env;
if (a) {
dfp->a64[0] = *a;
decimal64ToNumber((decimal64 *)dfp->a64, &dfp->a);
} else {
dfp->a64[0] = 0;
decNumberZero(&dfp->a);
}
if (b) {
dfp->b64[0] = *b;
decimal64ToNumber((decimal64 *)dfp->b64, &dfp->b);
} else {
dfp->b64[0] = 0;
decNumberZero(&dfp->b);
}
}
__attribute__ ((unused))
static void dfp_prepare_decimal128(struct PPC_DFP *dfp, uint64_t *a,
uint64_t *b, CPUPPCState *env)
{
decContextDefault(&dfp->context, DEC_INIT_DECIMAL128);
dfp_prepare_rounding_mode(&dfp->context, env->fpscr);
dfp->env = env;
if (a) {
dfp->a64[0] = a[HI_IDX];
dfp->a64[1] = a[LO_IDX];
decimal128ToNumber((decimal128 *)dfp->a64, &dfp->a);
} else {
dfp->a64[0] = dfp->a64[1] = 0;
decNumberZero(&dfp->a);
}
if (b) {
dfp->b64[0] = b[HI_IDX];
dfp->b64[1] = b[LO_IDX];
decimal128ToNumber((decimal128 *)dfp->b64, &dfp->b);
} else {
dfp->b64[0] = dfp->b64[1] = 0;
decNumberZero(&dfp->b);
}
}