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opcodes: ADD, AND, NOT

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This commit is contained in:
dogeystamp 2024-01-06 15:22:52 -05:00
parent f98719879a
commit 70603df303
Signed by: dogeystamp
GPG Key ID: 7225FE3592EFFA38
1 changed files with 55 additions and 3 deletions
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58
src/vm/instruction.rs
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@ -74,15 +74,15 @@ pub fn execute_instruction(vm: &mut VM, instr: u16) {
match opcode {
OpCode::BR => todo!("BR"),
OpCode::ADD => todo!("ADD"),
OpCode::ADD => op_add(vm, instr),
OpCode::LD => op_ld(vm, instr),
OpCode::ST => op_st(vm, instr),
OpCode::JSR => op_jsr(vm, instr),
OpCode::AND => todo!("AND"),
OpCode::AND => op_and(vm, instr),
OpCode::LDR => op_ldr(vm, instr),
OpCode::STR => op_str(vm, instr),
OpCode::RTI => todo!("RTI"),
OpCode::NOT => todo!("NOT"),
OpCode::NOT => op_not(vm, instr),
OpCode::LDI => op_ldi(vm, instr),
OpCode::STI => op_sti(vm, instr),
OpCode::JMP => todo!("JMP"),
@ -141,6 +141,10 @@ fn op_ldr(vm: &mut VM, instr: u16) {
vm.registers.set_reg_with_cond(dr, vm.mem.get_mem(addr));
}
////////////////
// Jumps
////////////////
fn op_jsr(vm: &mut VM, instr: u16) {
// this function also includes JSRR
vm.registers.r7 = vm.registers.pc;
@ -191,6 +195,54 @@ fn op_str(vm: &mut VM, instr: u16) {
vm.mem.set_mem(addr, vm.registers.get_reg(sr));
}
////////////////
// Arithmetic
////////////////
fn op_add(vm: &mut VM, instr: u16) {
let dr = (instr >> 9) & 0b111;
let sr1 = (instr >> 6) & 0b111;
if (instr >> 5) & 1 == 0 {
let sr2 = instr & 0b111;
let res = vm.registers.get_reg(sr1).wrapping_add(vm.registers.get_reg(sr2));
vm.registers.set_reg_with_cond(dr, res);
} else {
let imm = instr & 0x1f;
let res = vm.registers.get_reg(sr1).wrapping_add(imm);
vm.registers.set_reg_with_cond(dr, res);
}
}
fn op_and(vm: &mut VM, instr: u16) {
let dr = (instr >> 9) & 0b111;
let sr1 = (instr >> 6) & 0b111;
if (instr >> 5) & 1 == 0 {
let sr2 = instr & 0b111;
let res = vm.registers.get_reg(sr1) & vm.registers.get_reg(sr2);
vm.registers.set_reg_with_cond(dr, res);
} else {
let imm = instr & 0x1f;
let res = vm.registers.get_reg(sr1) & imm;
vm.registers.set_reg_with_cond(dr, res);
}
}
fn op_not(vm: &mut VM, instr: u16) {
let dr = (instr >> 9) & 0b111;
let sr = (instr >> 6) & 0b111;
// NOTE
// rustc is very friendly and tells you off if you use ~ as bitwise not
let res = !vm.registers.get_reg(sr);
vm.registers.set_reg_with_cond(sr, res);
}
////////////////
// Trap/trap routines
////////////////