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Fix overflow handling #19

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Fix overflow handling #19

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233c913
Introduced ADC/SBC from B-Em to fix overflow bugs.
uiopaubo Oct 6, 2024
f40875c
Merge branch 'master' into fix-overflow-handling
uiopaubo Oct 6, 2024
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159 changes: 90 additions & 69 deletions src/6502.c
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Original file line number Diff line number Diff line change
Expand Up @@ -98,76 +98,97 @@ uint16_t tempw;
int tempv,hc,al,ah;
uint8_t tempb;

#define ADC(temp) if (!p.d) \
{ \
tempw=(a+temp+(p.c?1:0)); \
p.v=(!((a^temp)&0x80)&&((a^tempw)&0x80)); \
a=tempw&0xFF; \
p.c=tempw&0x100; \
setzn(a); \
} \
else \
{ \
ah=0; \
tempb=a+temp+(p.c?1:0); \
if (!tempb) \
p.z=1; \
al=(a&0xF)+(temp&0xF)+(p.c?1:0); \
if (al>9) \
{ \
al-=10; \
al&=0xF; \
ah=1; \
} \
ah+=((a>>4)+(temp>>4)); \
if (ah&8) p.n=1; \
p.v=(((ah << 4) ^ a) & 128) && !((a ^ temp) & 128); \
p.c=0; \
if (ah>9) \
{ \
p.c=1; \
ah-=10; \
ah&=0xF; \
} \
a=(al&0xF)|(ah<<4); \
}
static inline void adc_nmos(uint8_t temp)
{
int al, ah;
uint8_t tempb;
int16_t tempw;

#define SBC(temp) if (!p.d) \
{ \
tempw=a-(temp+(p.c?0:1)); \
tempv=(short)a-(short)(temp+(p.c?0:1)); \
p.v=((a^(temp+(p.c?0:1)))&(a^(uint8_t)tempv)&0x80); \
p.c=tempv>=0;\
a=tempw&0xFF; \
setzn(a); \
} \
else \
{ \
hc=0; \
p.z=p.n=0; \
if (!((a-temp)-((p.c)?0:1))) \
p.z=1; \
al=(a&15)-(temp&15)-((p.c)?0:1); \
if (al&16) \
{ \
al-=6; \
al&=0xF; \
hc=1; \
} \
ah=(a>>4)-(temp>>4); \
if (hc) ah--; \
if ((a-(temp+((p.c)?0:1)))&0x80) \
p.n=1; \
p.v=(((a-(temp+((p.c)?0:1)))^temp)&128)&&((a^temp)&128); \
p.c=1; \
if (ah&16) \
{ \
p.c=0; \
ah-=6; \
ah&=0xF; \
} \
a=(al&0xF)|((ah&0xF)<<4); \
}
if (p.d)
{
ah = 0;
p.z = p.n = 0;
tempb = a + temp + (p.c ? 1:0);
if (!tempb)
p.z = 1;
al = (a & 0xF) + (temp & 0xF) + (p.c ? 1 : 0);
if (al > 9)
{
al -= 10;
al &= 0xF;
ah = 1;
}
ah += ((a >> 4) + (temp >> 4));
if (ah & 8)
p.n = 1;
p.v = (((ah << 4) ^ a) & 128) && !((a ^ temp) & 128);
p.c = 0;
if (ah > 9)
{
p.c = 1;
ah -= 10;
ah &= 0xF;
}
a = (al & 0xF) | (ah << 4);
}
else
{
tempw = (a + temp + (p.c ? 1 : 0));
p.v = (!((a ^ temp) & 0x80) && ((a ^ tempw) & 0x80));
a = tempw & 0xFF;
p.c = tempw & 0x100;
setzn(a);
}
}

static inline void sbc_nmos(uint8_t temp)
{
int hc6, al, ah, tempv;
uint8_t tempb;
int16_t tempw;

if (p.d)
{
hc6 = 0;
p.z = p.n = 0;
tempb = a - temp - ((p.c) ? 0 : 1);
if (!(tempb))
p.z = 1;
al = (a & 15) - (temp & 15) - (p.c ? 0 : 1);
if (al & 16)
{
al -= 6;
al &= 0xF;
hc6 = 1;
}
ah = (a >> 4) - (temp >> 4);
if (hc6)
ah--;
if ((a - (temp + (p.c ? 0 : 1))) & 0x80)
p.n = 1;
p.v = ((a ^ temp) & 0x80) && ((a ^ tempb) & 0x80);
p.c = 1;
if (ah & 16)
{
p.c = 0;
ah -= 6;
ah &= 0xF;
}
a = (al & 0xF) | ((ah & 0xF) << 4);
}
else
{
tempw = a-temp-(p.c ? 0 : 1);
tempv = (signed char)a -(signed char)temp-(p.c ? 0 : 1);
p.v = ((tempw & 0x80) > 0) ^ ((tempv & 0x100) != 0);
p.c = tempw >= 0;
a = tempw & 0xFF;
setzn(a);
}
}

#define ADC(temp) adc_nmos(temp)
#define SBC(temp) sbc_nmos(temp)

int output=0;
uint16_t oldpc2,oldpc;
Expand Down