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When an overflow exception occurs and OE is set the intermediate result should be adjusted (by subtracting from the exponent) to avoid rounding to inf. The same applies to an underflow exceptionion and UE (but adding to the exponent). To do this set the fp_status.rebias_overflow when OE is set and fp_status.rebias_underflow when UE is set as the FPU will recalculate in case of a overflow/underflow if the according rebias* is set. Signed-off-by: Lucas Mateus Castro (alqotel) <lucas.araujo@eldorado.org.br> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20220805141522.412864-3-lucas.araujo@eldorado.org.br> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
129 lines
3.7 KiB
C
129 lines
3.7 KiB
C
/*
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* PowerPC CPU routines for qemu.
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*
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* Copyright (c) 2017 Nikunj A Dadhania, 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 2.1 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 "qemu/osdep.h"
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#include "cpu.h"
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#include "cpu-models.h"
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#include "cpu-qom.h"
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#include "exec/log.h"
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#include "fpu/softfloat-helpers.h"
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#include "mmu-hash64.h"
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#include "helper_regs.h"
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#include "sysemu/tcg.h"
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target_ulong cpu_read_xer(const CPUPPCState *env)
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{
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if (is_isa300(env)) {
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return env->xer | (env->so << XER_SO) |
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(env->ov << XER_OV) | (env->ca << XER_CA) |
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(env->ov32 << XER_OV32) | (env->ca32 << XER_CA32);
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}
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return env->xer | (env->so << XER_SO) | (env->ov << XER_OV) |
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(env->ca << XER_CA);
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}
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void cpu_write_xer(CPUPPCState *env, target_ulong xer)
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{
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env->so = (xer >> XER_SO) & 1;
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env->ov = (xer >> XER_OV) & 1;
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env->ca = (xer >> XER_CA) & 1;
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/* write all the flags, while reading back check of isa300 */
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env->ov32 = (xer >> XER_OV32) & 1;
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env->ca32 = (xer >> XER_CA32) & 1;
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env->xer = xer & ~((1ul << XER_SO) |
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(1ul << XER_OV) | (1ul << XER_CA) |
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(1ul << XER_OV32) | (1ul << XER_CA32));
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}
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void ppc_store_vscr(CPUPPCState *env, uint32_t vscr)
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{
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env->vscr = vscr & ~(1u << VSCR_SAT);
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/* Which bit we set is completely arbitrary, but clear the rest. */
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env->vscr_sat.u64[0] = vscr & (1u << VSCR_SAT);
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env->vscr_sat.u64[1] = 0;
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set_flush_to_zero((vscr >> VSCR_NJ) & 1, &env->vec_status);
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}
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uint32_t ppc_get_vscr(CPUPPCState *env)
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{
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uint32_t sat = (env->vscr_sat.u64[0] | env->vscr_sat.u64[1]) != 0;
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return env->vscr | (sat << VSCR_SAT);
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}
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/* GDBstub can read and write MSR... */
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void ppc_store_msr(CPUPPCState *env, target_ulong value)
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{
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hreg_store_msr(env, value, 0);
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}
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void ppc_store_lpcr(PowerPCCPU *cpu, target_ulong val)
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{
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PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
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CPUPPCState *env = &cpu->env;
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env->spr[SPR_LPCR] = val & pcc->lpcr_mask;
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/* The gtse bit affects hflags */
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hreg_compute_hflags(env);
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}
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static inline void fpscr_set_rounding_mode(CPUPPCState *env)
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{
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int rnd_type;
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/* Set rounding mode */
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switch (env->fpscr & FP_RN) {
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case 0:
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/* Best approximation (round to nearest) */
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rnd_type = float_round_nearest_even;
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break;
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case 1:
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/* Smaller magnitude (round toward zero) */
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rnd_type = float_round_to_zero;
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break;
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case 2:
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/* Round toward +infinite */
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rnd_type = float_round_up;
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break;
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default:
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case 3:
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/* Round toward -infinite */
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rnd_type = float_round_down;
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break;
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}
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set_float_rounding_mode(rnd_type, &env->fp_status);
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}
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void ppc_store_fpscr(CPUPPCState *env, target_ulong val)
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{
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val &= FPSCR_MTFS_MASK;
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if (val & FPSCR_IX) {
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val |= FP_VX;
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}
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if ((val >> FPSCR_XX) & (val >> FPSCR_XE) & 0x1f) {
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val |= FP_FEX;
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}
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env->fpscr = val;
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env->fp_status.rebias_overflow = (FP_OE & env->fpscr) ? true : false;
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env->fp_status.rebias_underflow = (FP_UE & env->fpscr) ? true : false;
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if (tcg_enabled()) {
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fpscr_set_rounding_mode(env);
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}
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}
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