Added bit shift instructions.
SHL and SHR treat A and B as a 16 bit circular shift register and rotates them either left or right.
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@@ -22,6 +22,8 @@ Instruction instruction_set[] = {
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{0x06, "XOR"},
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{0x07, "NOTA"},
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{0x08, "NOTB"},
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{0x09, "SHL"},
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{0x0A, "SHR"},
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// Branch Operations:
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{0x10, "BRI"},
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{0x11, "BRQ"},
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@@ -6,6 +6,8 @@
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#include "cpu.h"
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#include "io.h"
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uint16_t shiftRegister;
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void initializeCPU(CPURegisters *cpu, uint8_t *programMemory, uint8_t *dataMemory) {
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cpu->A = 0;
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cpu->B = 0;
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@@ -80,6 +82,20 @@ uint8_t executeOperation(uint8_t Instruction, CPURegisters *cpu) {
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// NOTB - not B -> Q
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cpu->Q = ~cpu->B;
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break;
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case 0x09:
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// SHL - Shift AB left.
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shiftRegister = ((uint16_t)cpu->A << 8) | cpu->B;
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shiftRegister = (shiftRegister << 1) | (shiftRegister >> 15);
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cpu->A = shiftRegister >> 8;
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cpu->B = shiftRegister & 0xFF;
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break;
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case 0x0A:
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// SHR - Shift AB right.
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shiftRegister = ((uint16_t)cpu->A << 8) | cpu->B;
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shiftRegister = (shiftRegister >> 1) | (shiftRegister << 15);
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cpu->A = shiftRegister >> 8;
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cpu->B = shiftRegister & 0xFF;
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break;
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//
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// 1x - Branch Operations:
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//
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@@ -16,7 +16,7 @@ It has six registers:
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## List of Instructions:
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### Arithmetic and Logic Operations: 9 Instructions
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### Arithmetic and Logic Operations: 11 Instructions
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Hex Code | Mnemonic | Description
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-- | -- | --
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00 | ADD | Adds A, B, and the Carry Flag, the result is stored in Q.
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@@ -28,6 +28,8 @@ Hex Code | Mnemonic | Description
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06 | XOR | Bitwise xor of A and B, the result is stored in Q.
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07 | NOTA | Bitwise inversion of A, the result is stored in Q.
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08 | NOTB | Bitwise inversion of B, the result is stored in Q.
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09 | SHL | A and B form a circular shift register. Rotate this register left.
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0A | SHR | A and B form a circular shift register. Rotate this register right.
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### Branch Operations: 7 Instructions
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Hex Code | Mnemonic | Description
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