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better BRA support for 65c02+

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This commit is contained in:
Kelvin Sherlock 2016-05-27 15:54:43 -04:00
parent 3884f0b36a
commit e2d81bc221
1 changed files with 22 additions and 7 deletions
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29
emitBranch_6502.c
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@ -56,6 +56,7 @@ emitRelativeBranch(conditionType condition, valueType *target, valueType *fixupL
#define BNE_OPCODE 0xD0
#define NOP_OPCODE 0xEA
#define BEQ_OPCODE 0xF0
#define BRA_OPCODE 0x80
static byte conditionalBranchOpcodes[] = {
/* CARRY_COND */ BCS_OPCODE,
@ -66,7 +67,7 @@ emitRelativeBranch(conditionType condition, valueType *target, valueType *fixupL
/* LEQ_COND */ COMPOUND,
/* SLT_COND */ COMPOUND,
/* SLEQ_COND */ COMPOUND,
/* ALWAYS_COND */ NOP_OPCODE,
/* ALWAYS_COND */ COMPOUND,
/* NOT_CARRY_COND */ BCC_OPCODE,
/* NOT_ZERO_COND */ BNE_OPCODE,
/* NOT_NEGATIVE_COND */ BPL_OPCODE,
@ -85,11 +86,21 @@ emitRelativeBranch(conditionType condition, valueType *target, valueType *fixupL
if (fixupLocation != NULL)
for (i=0; i<COMPOUND_BRANCH_MAX; i++)
fixupLocation[i].value = -1;
if (conditionalBranchOpcodes[(int)condition] != COMPOUND) {
emitByte(conditionalBranchOpcodes[(int)condition]);
conditionalFixup(0);
} else switch (condition) {
case ALWAYS_COND:
if (processor > P6502) {
emitByte(BRA_OPCODE); conditionalFixup(0);
} else {
emitByte(BCS_OPCODE); conditionalFixup(0);
emitByte(BCC_OPCODE); conditionalFixup(1);
}
break;
case GT_COND:
emitByte(BEQ_OPCODE); emitByte(2);
emitByte(BCS_OPCODE); conditionalFixup(0);
@ -150,13 +161,17 @@ emitJump(valueType *target, simpleFixupListType *previousFixups)
result = previousFixups;
if (positionIndependentCodeMode) {
if (target == NULL) {
emitRelativeBranch(CARRY_COND, NULL, picFixup);
result = buildSimpleFixupList(picFixup[0], result);
emitRelativeBranch(NOT_CARRY_COND, NULL, picFixup);
result = buildSimpleFixupList(picFixup[0], result);
if (processor > P6502) {
emitRelativeBranch(ALWAYS_COND, NULL, picFixup);
result = buildSimpleFixupList(picFixup[0], result);
} else {
emitRelativeBranch(CARRY_COND, NULL, picFixup);
result = buildSimpleFixupList(picFixup[0], result);
emitRelativeBranch(NOT_CARRY_COND, NULL, picFixup);
result = buildSimpleFixupList(picFixup[0], result);
}
} else {
emitRelativeBranch(CARRY_COND, target, NULL);
emitRelativeBranch(NOT_CARRY_COND, target, NULL);
emitRelativeBranch(ALWAYS_COND, target, NULL);
}
} else {
emitByte(JUMP_OPCODE);