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uxn
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Optimize opcode 0 handling.

This commit is contained in:
Andrew Alderwick 2023-01-12 13:02:04 +00:00
parent e0c2da0700
commit 230e8dda34
1 changed files with 13 additions and 10 deletions
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23
src/uxn.c
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@ -33,10 +33,11 @@ int
uxn_eval(Uxn *u, Uint16 pc)
{
Uint8 kptr, *sp;
Uint16 a, b, c, j, k, bs, instr;
Uint16 a, b, c, j, k, bs, instr, opcode;
Stack *src, *dst;
if(!pc || u->dev[0x0f]) return 0;
while((instr = u->ram[pc++])) {
for(;;) {
instr = u->ram[pc++];
/* Return Mode */
if(instr & 0x40) { src = u->rst; dst = u->wst; }
else { src = u->wst; dst = u->rst; }
@ -45,14 +46,17 @@ uxn_eval(Uxn *u, Uint16 pc)
else sp = &src->ptr;
/* Short Mode */
bs = instr & 0x20;
switch(instr & 0x1f) {
case 0x00:
opcode = instr & 0x1f;
switch(opcode - (!opcode * (instr >> 5))) {
/* Literals/Calls */
if(instr == 0x20) /* JMI */ { PEEK16(a, pc) pc = a; }
else if(instr == 0x40) /* JCI */ { sp = &u->wst->ptr; src = u->wst; POP8(b) if(b) { PEEK16(a, pc) pc = a; } else pc += 2; }
else if(instr == 0x60) /* JSI */ { PUSH16(u->rst, pc + 2) PEEK16(a, pc) pc = a; }
else if(bs) /* LIT2 */ { PEEK16(a, pc) PUSH16(src, a) pc += 2; }
else /* LITr */ { a = u->ram[pc++]; PUSH8(src, a) } break;
case -0x0: /* BRK */ return 1;
case -0x1: /* JMI */ PEEK16(a, pc) pc = a; break;
case -0x2: /* JCI */ sp = &u->wst->ptr; src = u->wst; POP8(b) if(b) { PEEK16(a, pc) pc = a; } else pc += 2; break;
case -0x3: /* JSI */ PUSH16(u->rst, pc + 2) PEEK16(a, pc) pc = a; break;
case -0x4: /* LIT */
case -0x6: /* LITr */ a = u->ram[pc++]; PUSH8(src, a) break;
case -0x5: /* LIT2 */
case -0x7: /* LIT2r */ PEEK16(a, pc) PUSH16(src, a) pc += 2; break;
/* ALU */
case 0x01: /* INC */ POP(a) PUSH(src, a + 1) break;
case 0x02: /* POP */ POP(a) break;
@ -87,7 +91,6 @@ uxn_eval(Uxn *u, Uint16 pc)
case 0x1f: /* SFT */ POP8(a) POP(b) PUSH(src, b >> (a & 0x0f) << ((a & 0xf0) >> 4)) break;
}
}
return 1;
}
int