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xrick2gs
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A perhaps more cycle friendly pei blitter

This commit is contained in:
dwsJason 2018-08-28 22:08:57 -04:00
parent 8c6b911c6e
commit 68367599f4
1 changed files with 56 additions and 1 deletions
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57
bin/blit/source/blit.c
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@ -159,7 +159,7 @@ int ADC(int A, int delta, int* C)
call with X
*/
void CompileBlockPEI(RAWDATA *result, int x, int width)
void CompileBlockPEI_fwd(RAWDATA *result, int x, int width)
{
int clocks = 0;
int A = 0; // What's in the accumulator
@ -213,6 +213,61 @@ void CompileBlockPEI(RAWDATA *result, int x, int width)
clocks += AddLine("","JMP","BRET ;%d cycles",clocks+3,3);
}
void CompileBlockPEI(RAWDATA *result, int x, int width)
{
int clocks = 0;
int A = 0x400; // What's in the accumulator
int C = 0;
clocks += AddLine("","TCD"," ; Set DP $%04X",A,2);
clocks += AddLine("","ADC","#%d",(7*160)-(1024)+((x+width)>>1)-1,3);
A+=(7*160)-(1024)+((x+width)>>1)-1;
int S=A;
clocks += AddLine("","TCS"," ; Set S $%04X",A,2);
int dp = 0x400;
for (int y = 7; y >= 0; --y)
{
int p = y * 160;
for (int xs = 316; xs >= 0; xs-=4)
{
int xbyte = (xs>>1) + p;
if ((xs>=x)&&(xs<(x+width)))
{
if ((dp & 0xFF00) != (xbyte & 0xFF00))
{
int delta = (xbyte&0xFF00) - (A+C); //(dp & 0xFF00);
A = ADC(A,delta,&C);
clocks += AddLine("","ADC","#%d",delta,3);
clocks += AddLine("","TCD"," ; Set DP $%04X",A,2);
}
clocks += AddLine("", "PEI", "$%02X", xbyte & 0xFF, 6);
dp = xbyte;
}
}
if (y > 0)
{
S-=160;
int delta = S - (A+C);
A = ADC(A,delta,&C);
clocks += AddLine("", "ADC", "#%d", delta, 3);
clocks += AddLine("","TCS"," ; Set S $%04X",A,2);
}
}
// clocks += AddLine("","RTL"," ;%d cycles",clocks+6,6);
clocks += AddLine("","JMP","BRET ;%d cycles",clocks+3,3);
}
RAWDATA* CompilePEI()
{
RAWDATA* result = (RAWDATA*)malloc(sizeof(RAWDATA));