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Merged
lachlanharrisdev merged 1 commit into from
Sep 22, 2025
Merged

Add remaining LC-3 instructions, refactor slightly #3

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1 change: 0 additions & 1 deletion include/instructions.h
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,6 @@ void execute_lea(uint16_t instr);
void execute_st(uint16_t instr);
void execute_sti(uint16_t instr);
void execute_str(uint16_t instr);
void execute_math(uint16_t instr);
void execute_trap(uint16_t instr);
void execute_bad_opcode(uint16_t instr);

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2 changes: 1 addition & 1 deletion include/utils.h
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Expand Up @@ -8,7 +8,7 @@
#include <stdint.h>
#include <signal.h>

void handle_interrupt();
void handle_interrupt(int signal);
void disable_input_buffering();
void restore_input_buffering();
void update_flags(uint16_t r);
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151 changes: 105 additions & 46 deletions src/instructions.c
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Expand Up @@ -140,7 +140,8 @@ enum
};
*/

void execute_add(uint16_t instr) {
void execute_add(uint16_t instr)
{
uint16_t r0 = GET_DR(instr);
uint16_t r1 = GET_SR1(instr);
uint16_t imm_flag = GET_IMM_FLAG5(instr);
Expand All @@ -155,7 +156,8 @@ void execute_add(uint16_t instr) {
update_flags(r0);
}

void execute_and(uint16_t instr) {
void execute_and(uint16_t instr)
{
uint16_t r0 = GET_DR(instr);
uint16_t r1 = GET_SR1(instr);
uint16_t imm_flag = GET_IMM_FLAG5(instr);
Expand All @@ -170,13 +172,97 @@ void execute_and(uint16_t instr) {
update_flags(r0);
}

void execute_not(uint16_t instr) {
void execute_not(uint16_t instr)
{
uint16_t r0 = GET_DR(instr);
uint16_t r1 = GET_SR1(instr);
reg[r0] = ~reg[r1];
update_flags(r0);
}

void execute_br(uint16_t instr)
{
uint16_t pc_offset = sext(GET_PC_OFFSET9(instr), 9);
uint16_t cond_flag = (instr >> 9) & 0x7;
if (cond_flag & reg[R_COND]) {
reg[R_PC] += pc_offset;
}
}

void execute_jmp(uint16_t instr)
{
uint16_t r1 = GET_BASE_R(instr);
reg[R_PC] = reg[r1];
}

void execute_jsr(uint16_t instr)
{
uint16_t long_flag = (instr >> 11) & 1;
reg[R_R7] = reg[R_PC];
if (long_flag) {
uint16_t pc_offset = sext(GET_PC_OFFSET11(instr), 11);
reg[R_PC] += pc_offset;
} else {
uint16_t r1 = GET_BASE_R(instr);
reg[R_PC] = reg[r1];
}
}

void execute_ld(uint16_t instr)
{
uint16_t r0 = GET_DR(instr);
uint16_t pc_offset = sext(GET_PC_OFFSET9(instr), 9);
reg[r0] = mem_read(reg[R_PC] + pc_offset);
update_flags(r0);
}

void execute_ldr(uint16_t instr)
{
uint16_t r0 = GET_DR(instr);
uint16_t r1 = GET_BASE_R(instr);
uint16_t offset6 = sext(GET_OFFSET6(instr), 6);
reg[r0] = mem_read(reg[r1] + offset6);
update_flags(r0);
}

void execute_ldi(uint16_t instr)
{
uint16_t r0 = GET_DR(instr);
uint16_t pc_offset = sext(GET_PC_OFFSET9(instr), 9);
reg[r0] = mem_read(mem_read(reg[R_PC] + pc_offset));
update_flags(r0);
}

void execute_lea(uint16_t instr)
{
uint16_t r0 = GET_DR(instr);
uint16_t pc_offset = sext(GET_PC_OFFSET9(instr), 9);
reg[r0] = reg[R_PC] + pc_offset;
update_flags(r0);
}

void execute_st(uint16_t instr)
{
uint16_t r0 = GET_DR(instr);
uint16_t pc_offset = sext(GET_PC_OFFSET9(instr), 9);
mem_write(reg[R_PC] + pc_offset, reg[r0]);
}

void execute_sti(uint16_t instr)
{
uint16_t r0 = GET_DR(instr);
uint16_t pc_offset = sext(GET_PC_OFFSET9(instr), 9);
mem_write(mem_read(reg[R_PC] + pc_offset), reg[r0]);
}

void execute_str(uint16_t instr)
{
uint16_t r0 = GET_DR(instr);
uint16_t r1 = GET_BASE_R(instr);
uint16_t offset6 = sext(GET_OFFSET6(instr), 6);
mem_write(reg[r1] + offset6, reg[r0]);
}

static void trap_dispatch(uint8_t trapvect8) {
switch (trapvect8) {
case TRAP_GETC: trap_getc(); break;
Expand All @@ -193,6 +279,7 @@ static void trap_dispatch(uint8_t trapvect8) {

void execute_trap(uint16_t instr) {
uint8_t trapvect8 = instr & 0xFF;
reg[R_R7] = reg[R_PC];
trap_dispatch(trapvect8);
}

Expand All @@ -205,52 +292,24 @@ void execute_bad_opcode(uint16_t instr) {







void execute_instruction(uint16_t instruction) {
uint16_t op = GET_OP(instruction);
switch (op) {
case OP_ADD: execute_add(instruction); break;
case OP_AND: execute_and(instruction); break;
case OP_NOT: execute_not(instruction); break;
case OP_TRAP: execute_trap(instruction); break;
/*
case OP_BR:
execute_br((uint16_t)instruction);
break;
case OP_JMP:
execute_jmp((uint16_t)instruction);
break;
case OP_JSR:
execute_jsr((uint16_t)instruction);
break;
case OP_LD:
execute_ld((uint16_t)instruction);
break;
case OP_LDI:
execute_ldi((uint16_t)instruction);
break;
case OP_LDR:
execute_ldr((uint16_t)instruction);
break;
case OP_LEA:
execute_lea((uint16_t)instruction);
break;
case OP_ST:
execute_st((uint16_t)instruction);
break;
case OP_STI:
execute_sti((uint16_t)instruction);
break;
case OP_STR:
execute_str((uint16_t)instruction);
break;
*/
default:
execute_bad_opcode((uint16_t)instruction);
break;
case OP_ADD: execute_add(instruction); break;
case OP_AND: execute_and(instruction); break;
case OP_NOT: execute_not(instruction); break;
case OP_TRAP: execute_trap(instruction); break;
case OP_BR: execute_br(instruction); break;
case OP_JMP: execute_jmp(instruction); break;
case OP_JSR: execute_jsr(instruction); break;
case OP_LD: execute_ld(instruction); break;
case OP_LDI: execute_ldi(instruction); break;
case OP_LDR: execute_ldr(instruction); break;
case OP_LEA: execute_lea(instruction); break;
case OP_ST: execute_st(instruction); break;
case OP_STI: execute_sti(instruction); break;
case OP_STR: execute_str(instruction); break;
default: execute_bad_opcode(instruction); break;
}
}

5 changes: 3 additions & 2 deletions src/utils.c
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Expand Up @@ -48,8 +48,9 @@ uint16_t check_key()



void handle_interrupt()
void handle_interrupt(int signal)
{
(void)signal;
restore_input_buffering();
printf("\n");
exit(-2);
Expand Down Expand Up @@ -82,7 +83,7 @@ void read_image_file(FILE* file)
}
origin = swap16(origin);

uint16_t max_read = UINT16_MAX - origin;
uint16_t max_read = MEMORY_MAX - origin;
uint16_t* p = memory + origin;
size_t read = fread(p, sizeof(uint16_t), max_read, file);

Expand Down