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88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
/*
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* Helpers for emulation of FPU-related MIPS instructions.
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*
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* Copyright (C) 2004-2005 Jocelyn Mayer
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*
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* SPDX-License-Identifier: LGPL-2.1-or-later
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*/
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#include "fpu/softfloat-helpers.h"
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#include "cpu.h"
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extern const FloatRoundMode ieee_rm[4];
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uint32_t float_class_s(uint32_t arg, float_status *fst);
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uint64_t float_class_d(uint64_t arg, float_status *fst);
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static inline void restore_rounding_mode(CPUMIPSState *env)
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{
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set_float_rounding_mode(ieee_rm[env->active_fpu.fcr31 & 3],
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&env->active_fpu.fp_status);
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}
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static inline void restore_flush_mode(CPUMIPSState *env)
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{
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set_flush_to_zero((env->active_fpu.fcr31 & (1 << FCR31_FS)) != 0,
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&env->active_fpu.fp_status);
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}
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static inline void restore_snan_bit_mode(CPUMIPSState *env)
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{
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bool nan2008 = env->active_fpu.fcr31 & (1 << FCR31_NAN2008);
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/*
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* With nan2008, SNaNs are silenced in the usual way.
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* Before that, SNaNs are not silenced; default nans are produced.
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*/
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set_snan_bit_is_one(!nan2008, &env->active_fpu.fp_status);
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set_default_nan_mode(!nan2008, &env->active_fpu.fp_status);
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}
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static inline void restore_fp_status(CPUMIPSState *env)
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{
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restore_rounding_mode(env);
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restore_flush_mode(env);
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restore_snan_bit_mode(env);
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}
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static inline void fp_reset(CPUMIPSState *env)
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{
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restore_fp_status(env);
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/*
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* According to MIPS specifications, if one of the two operands is
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* a sNaN, a new qNaN has to be generated. This is done in
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* floatXX_silence_nan(). For qNaN inputs the specifications
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* says: "When possible, this QNaN result is one of the operand QNaN
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* values." In practice it seems that most implementations choose
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* the first operand if both operands are qNaN. In short this gives
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* the following rules:
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* 1. A if it is signaling
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* 2. B if it is signaling
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* 3. A (quiet)
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* 4. B (quiet)
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* A signaling NaN is always silenced before returning it.
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*/
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set_float_2nan_prop_rule(float_2nan_prop_s_ab,
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&env->active_fpu.fp_status);
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}
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/* MSA */
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enum CPUMIPSMSADataFormat {
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DF_BYTE = 0,
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DF_HALF,
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DF_WORD,
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DF_DOUBLE
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};
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static inline void restore_msa_fp_status(CPUMIPSState *env)
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{
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float_status *status = &env->active_tc.msa_fp_status;
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int rounding_mode = (env->active_tc.msacsr & MSACSR_RM_MASK) >> MSACSR_RM;
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bool flush_to_zero = (env->active_tc.msacsr & MSACSR_FS_MASK) != 0;
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set_float_rounding_mode(ieee_rm[rounding_mode], status);
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set_flush_to_zero(flush_to_zero, status);
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set_flush_inputs_to_zero(flush_to_zero, status);
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}
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