Add LEA instruction implementation

[Copilot]

• Explore repository structure and understand existing patterns
• Create LEA.h in includes/GenieSys/CpuOperations
• Create LEA.cpp in src/CpuOperations
• Create LEATest.cpp in test/CpuOperations
• Include LEA in CpuOperation::getOperations
• Update src/CMakeLists.txt to include LEA.cpp
• Update test/CMakeLists.txt to include LEATest.cpp
• Build and verify all tests pass (763 tests passed)
• Run code review (no issues found)
• Clean up build artifacts
• Add check for invalid EA modes (0b000, 0b001, 0b011, 0b100) that triggers illegal instruction trap
• Add tests for illegal instruction cases

Fixes #51

Original prompt

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This section details on the original issue you should resolve

<issue_title>Implement LEA</issue_title>
<issue_description>Operation: < ea > → An

Assembler Syntax: LEA < ea > ,An

Attributes: Size = (Long)

Description: Loads the effective address into the specified address register. All 32 bits of
the address register are affected by this instruction.

Condition Codes:
Not affected.

Instruction Format: 0100rrr111mmmaaa
r -> An bits
m -> < ea > mode bits
a -> < ea > address bits

Feel free to reference docs/86KPM.pdf for more details about instruction behavior.

Please follow existing patterns in the code. </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Implement LEA #51

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[PaulTrampert]

@copilot Please try again.

I would expect the following changes:

• Add LEA.h to includes/GenieSys/CpuOperations
• Add LEA.cpp to src/CpuOperations
• Add LEATest.cpp to test/CpuOperations
• Include LEA in CpuOperation::getOperations

[Copilot]

@copilot Please try again.

I would expect the following changes:...

Done in 7785bee. Added LEA.h, LEA.cpp, LEATest.cpp, and included LEA in CpuOperation::getOperations following the existing patterns in the codebase.

[PaulTrampert]

@copilot It looks like you specified (A3) as the effective address source and set the value of A3 to 0xAABBCCDD. Rather than copying 0xAABBCCDD into A5, this should copy the 32-bit value found from bus->readLong(0xAABBCCDD) into A5.

[Copilot]

@copilot It looks like you specified (A3) as the effective address source and set the value of A3 to 0xAABBCCDD. Rather than copying 0xAABBCCDD into A5, this should copy the 32-bit value found from `b...

I want to clarify the expected behavior. LEA (Load Effective Address) traditionally loads the computed address itself into the destination register, not the data at that address. For LEA (A3),A5, the effective address IS the value in A3 (0xAABBCCDD), so A5 should receive 0xAABBCCDD.

Are you saying that for this codebase, LEA should instead read from memory at the effective address? Or should I use a different addressing mode in the test (like absolute addressing or displacement mode) to make the test more meaningful?

[PaulTrampert]

@copilot I'm sorry, your PR is correct. My understanding of the documentation was mistaken.

[PaulTrampert]

@copilot Please add a check to the instruction that checks for ea modes of 0b000, 0b001, 0b011, and 0b100. If the ea mode is any of these, return cpu->trap(TV_ILLEGAL_INSTR);.

[Copilot]

@copilot Please add a check to the instruction that checks for ea modes of 0b000, 0b001, 0b011, and 0b100. If the ea mode is any of these, return cpu->trap(TV_ILLEGAL_INSTR);.

Added the check in 8e2109e. The LEA execute method now returns cpu->trap(TV_ILLEGAL_INSTR) when the EA mode is 0b000 (Dn), 0b001 (An), 0b011 ((An)+), or 0b100 (-(An)).

[PaulTrampert]

@copilot Please add a test for the illegal instruction case.

[Copilot]

@copilot Please add a test for the illegal instruction case.

Added in 771456b. Added 4 tests covering each of the illegal EA modes (0b000 Data Register Direct, 0b001 Address Register Direct, 0b011 Post-Increment, 0b100 Pre-Decrement), verifying they return 34 cycles and trigger the illegal instruction trap handler.