144 lines
2.8 KiB
C++
144 lines
2.8 KiB
C++
#include "dsp.h"
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/*
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DSP rec_v1
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Tries to emulate a guesstimation of the aica dsp, by directly emitting x86 opcodes.
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This was my first dsp implementation, as implemented for nullDC 1.0.3.
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This was derived from a schematic I drew for the dsp, based on
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liberal interpretation of known specs, the saturn dsp, digital
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electronics assumptions, as well as "best-fitted" my typical
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test game suite.
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Initial code by skmp, now part of the reicast project.
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See LICENSE & COPYRIGHT files further details
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*/
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alignas(4096) dsp_t dsp;
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//float format is ?
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u16 DYNACALL PACK(s32 val)
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{
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int sign = (val >> 23) & 0x1;
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u32 temp = (val ^ (val << 1)) & 0xFFFFFF;
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int exponent = 0;
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for (int k = 0; k < 12; k++)
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{
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if (temp & 0x800000)
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break;
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temp <<= 1;
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exponent += 1;
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}
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if (exponent < 12)
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val <<= exponent;
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else
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val <<= 11;
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val = (val >> 11) & 0x7FF; // avoid sign extension of mantissa
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val |= sign << 15;
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val |= exponent << 11;
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return (u16)val;
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}
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s32 DYNACALL UNPACK(u16 val)
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{
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int sign = (val >> 15) & 0x1;
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int exponent = (val >> 11) & 0xF;
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int mantissa = val & 0x7FF;
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s32 uval = mantissa << 11;
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uval |= sign << 22; // take the sign in bit 22
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if (exponent > 11)
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exponent = 11; // cap exponent to 11 for denormals
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else
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uval ^= 1 << 22; // reverse bit 22 for normals
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uval |= sign << 23; // actual sign bit
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uval <<= 8;
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uval >>= 8;
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uval >>= exponent;
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return uval;
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}
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void DecodeInst(const u32 *IPtr, _INST *i)
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{
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i->TRA = (IPtr[0] >> 9) & 0x7F;
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i->TWT = IPtr[0] & 0x100;
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i->TWA = (IPtr[0] >> 1) & 0x7F;
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i->XSEL = IPtr[1] & 0x8000;
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i->YSEL = (IPtr[1] >> 13) & 3;
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i->IRA = (IPtr[1] >> 7) & 0x3F;
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i->IWT = IPtr[1] & 0x40;
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i->IWA = (IPtr[1] >> 1) & 0x1F;
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i->TABLE = IPtr[2] & 0x8000;
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i->MWT = IPtr[2] & 0x4000;
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i->MRD = IPtr[2] & 0x2000;
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i->EWT = IPtr[2] & 0x1000;
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i->EWA = (IPtr[2] >> 8) & 0x0F;
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i->ADRL = IPtr[2] & 0x80;
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i->FRCL = IPtr[2] & 0x40;
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i->SHIFT = (IPtr[2] >> 4) & 3;
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i->YRL = IPtr[2] & 8;
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i->NEGB = IPtr[2] & 4;
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i->ZERO = IPtr[2] & 2;
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i->BSEL = IPtr[2] & 1;
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i->NOFL = IPtr[3] & 0x8000;
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i->MASA = (IPtr[3] >> 9) & 0x3f;
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i->ADREB = IPtr[3] & 0x100;
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i->NXADR = IPtr[3] & 0x80;
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}
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#if FEAT_DSPREC != DYNAREC_NONE
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void dsp_init()
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{
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memset(&dsp, 0, sizeof(dsp));
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dsp.RBL = 0x8000 - 1;
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dsp.RBP = 0;
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dsp.regs.MDEC_CT = 1;
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dsp.dyndirty = true;
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dsp_rec_init();
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}
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void dsp_step()
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{
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if (dsp.dyndirty)
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{
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dsp.dyndirty = false;
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dsp_recompile();
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}
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if (dsp.Stopped)
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return;
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dsp_rec_step();
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}
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void dsp_writenmem(u32 addr)
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{
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if (addr >= 0x3400 && addr < 0x3C00)
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{
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dsp.dyndirty = true;
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}
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else if (addr >= 0x4000 && addr < 0x4400)
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{
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// TODO proper sharing of memory with sh4 through DSPData
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memset(dsp.TEMP, 0, sizeof(dsp.TEMP));
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}
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else if (addr >= 0x4400 && addr < 0x4500)
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{
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// TODO proper sharing of memory with sh4 through DSPData
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memset(dsp.MEMS, 0, sizeof(dsp.MEMS));
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}
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}
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void dsp_term()
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{
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}
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#endif
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