prodriguez/choco-chip8
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interpreter memory vector access now always uses bound checking

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This commit is contained in:
Pablo Rodriguez
2024-11-29 20:14:59 -05:00
parent 8c49ec6d86
commit 3c30d2a04f
1 changed files with 9 additions and 9 deletions
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18
Interpreter.cpp
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@@ -71,7 +71,7 @@ void Interpreter::tick() {
// fetch instruction
sreg_t iInstAddr = mvSpecialReg[SR_PC];
unsigned inst = (mvMemory[iInstAddr] << 8) | mvMemory[iInstAddr + 1];
unsigned inst = (mvMemory.at(iInstAddr) << 8) | mvMemory.at(iInstAddr + 1);
// increment program counter
mvSpecialReg[SR_PC] += 2;
@@ -163,18 +163,18 @@ void Interpreter::tick() {
mvSpecialReg[SR_I] = scLowRestFontAddr + 5 * mvReg[iRegDst];
break;
case 0xF033: // FX33 - convert to bcd
mvMemory[mvSpecialReg[SR_I]] = (mvReg[iRegDst] / 100) % 10;
mvMemory[mvSpecialReg[SR_I] + 1] = (mvReg[iRegDst] / 10) % 10;
mvMemory[mvSpecialReg[SR_I] + 2] = mvReg[iRegDst] % 10;
mvMemory.at(mvSpecialReg[SR_I]) = (mvReg[iRegDst] / 100) % 10;
mvMemory.at(mvSpecialReg[SR_I] + 1) = (mvReg[iRegDst] / 10) % 10;
mvMemory.at(mvSpecialReg[SR_I] + 2) = mvReg[iRegDst] % 10;
break;
case 0xF055: // FX55 - dump registers
for(int i = 0; i <= iRegDst - R_V0; i++) {
mvMemory[mvSpecialReg[SR_I]++] = mvReg[R_V0 + i];
mvMemory.at(mvSpecialReg[SR_I]++) = mvReg[R_V0 + i];
}
break;
case 0xF065: // FX65 - restore registers
for(int i = 0; i <= iRegDst - R_V0; i++) {
mvReg[R_V0 + i] = mvMemory[mvSpecialReg[SR_I]++];
mvReg[R_V0 + i] = mvMemory.at(mvSpecialReg[SR_I]++);
}
break;
default:
@@ -272,14 +272,14 @@ void Interpreter::executeDraw(uint8_t x, uint8_t y, uint8_t n) {
uint16_t spriteRowBits;
if(mIsHighResMode) {
// draws an 8xN sprite
spriteRowBits = mvMemory[iMemAddr++] << 8;
spriteRowBits = mvMemory.at(iMemAddr++) << 8;
if(n == 0) {
// draws an 16xN sprite, so fetch another byte from sprite data
spriteRowBits |= mvMemory[iMemAddr++];
spriteRowBits |= mvMemory.at(iMemAddr++);
}
} else {
// in low-res mode, each sprite pixel draws two on-screen pixels
spriteRowBits = gcvLowResToHighResRowLookupTable[mvMemory[iMemAddr++]];
spriteRowBits = gcvLowResToHighResRowLookupTable[mvMemory.at(iMemAddr++)];
}
// convert to bitset and shift into absolute horizontal position on the screen