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Diffstat (limited to 'src/emu/sound/scspdsp.c')
-rw-r--r--src/emu/sound/scspdsp.c52
1 files changed, 41 insertions, 11 deletions
diff --git a/src/emu/sound/scspdsp.c b/src/emu/sound/scspdsp.c
index 9a417c47443..bb30dd376be 100644
--- a/src/emu/sound/scspdsp.c
+++ b/src/emu/sound/scspdsp.c
@@ -6,19 +6,49 @@
static UINT16 PACK(INT32 val)
{
- //cut to 16 bits
- INT32 f=((UINT32 ) val)>>8;
- return f;
+ UINT32 temp;
+ int sign,exponent,k;
+
+ sign = (val >> 23) & 0x1;
+ temp = (val ^ (val << 1)) & 0xFFFFFF;
+ exponent = 0;
+ for (k=0; k<12; k++)
+ {
+ if (temp & 0x800000)
+ break;
+ temp <<= 1;
+ exponent += 1;
+ }
+ if (exponent < 12)
+ val = (val << exponent) & 0x3FFFFF;
+ else
+ val <<= 11;
+ val >>= 11;
+ val |= sign << 15;
+ val |= exponent << 11;
+
+ return (UINT16)val;
}
static INT32 UNPACK(UINT16 val)
{
- INT32 r=val<<8;
- r<<=8;
- r>>=8;
- //if(r&0x00800000)
- // r|=0xFF000000;
- return r;
+ int sign,exponent,mantissa;
+ INT32 uval;
+
+ sign = (val >> 15) & 0x1;
+ exponent = (val >> 11) & 0xF;
+ mantissa = val & 0x7FF;
+ uval = mantissa << 11;
+ if (exponent > 11)
+ exponent = 11;
+ else
+ uval |= (sign ^ 1) << 22;
+ uval |= sign << 23;
+ uval <<= 8;
+ uval >>= 8;
+ uval >>= exponent;
+
+ return uval;
}
void SCSPDSP_Init(struct _SCSPDSP *DSP)
@@ -125,7 +155,7 @@ void SCSPDSP_Step(struct _SCSPDSP *DSP)
if(IRA<=0x1f)
INPUTS=DSP->MEMS[IRA];
else if(IRA<=0x2F)
- INPUTS=DSP->MIXS[IRA-0x20]<<8; //MIXS is 16 bit
+ INPUTS=DSP->MIXS[IRA-0x20]<<4; //MIXS is 20 bit
else if(IRA<=0x31)
INPUTS=0;
@@ -298,7 +328,7 @@ void SCSPDSP_Step(struct _SCSPDSP *DSP)
void SCSPDSP_SetSample(struct _SCSPDSP *DSP,INT32 sample,int SEL,int MXL)
{
//DSP->MIXS[SEL]+=sample<<(MXL+1)/*7*/;
- DSP->MIXS[SEL]+=sample<<7;
+ DSP->MIXS[SEL]+=sample;
// if(MXL)
// int a=1;
}