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