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[#768] msp430x: Fix immediate addressing #138

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[#768] msp430x: Fix immediate addressing #138

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17 changes: 14 additions & 3 deletions src/Emulator/Peripherals/Peripherals/CPU/MSP430X/MSP430X.cs
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Original file line number Diff line number Diff line change
@@ -525,10 +525,21 @@ private uint GetOperandValue(Registers register, AddressingMode addressingMode,
{
uint registerValue = GetRegisterValue(register, addressingMode);
var offset = (accessWidth != AccessWidth._8bit) || register == Registers.PC ? 2U : 1U;
address = (ulong)registerValue | addressExtension;
address &= 0xFFFFF;
SetRegisterValue(register, (uint)(registerValue + offset) & 0xFFFFF);
return PerformMemoryRead(address, accessWidth);
if (register == Registers.PC) {
// immediate addressing (@PC+)
// get immediate value @PC and append the extended address
uint imm20 = PerformMemoryRead(registerValue, AccessWidth._16bit);
imm20 |= addressExtension;
return imm20;
} else {
// indirect addressing (@Rn+)
// get addr in the register and append the extended address
// then access the memory
address = (ulong)registerValue | addressExtension;
address &= 0xFFFFF;
return PerformMemoryRead(address, accessWidth);
}
}

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