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chore(cpu): refactor the barrel shifter once again

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This commit is contained in:
Rekai Nyangadzayi Musuka
2022-01-17 15:55:55 -04:00
parent d4d2fedfbe
commit a7a44c4463
2 changed files with 110 additions and 66 deletions
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19
src/cpu/arm/data_processing.zig
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@@ -1,6 +1,6 @@
const std = @import("std");
const BarrelShifter = @import("barrel_shifter.zig");
const shifter = @import("barrel_shifter.zig");
const Bus = @import("../../Bus.zig");
const Arm7tdmi = @import("../../cpu.zig").Arm7tdmi;
const InstrFn = @import("../../cpu.zig").ArmInstrFn;
@@ -11,21 +11,14 @@ pub fn dataProcessing(comptime I: bool, comptime S: bool, comptime instrKind: u4
const rd = opcode >> 12 & 0xF;
const rn = opcode >> 16 & 0xF;
if (S and rd == 0xF) std.debug.panic("[CPU] Data Processing Instruction w/ S set and Rd == 15", .{});
var op1: u32 = undefined;
if (rn == 0xF) {
op1 = cpu.fakePC();
} else {
op1 = cpu.r[rn];
}
const op1 = if (rn == 0xF) cpu.fakePC() else cpu.r[rn];
var op2: u32 = undefined;
if (I) {
const amount = @truncate(u8, (opcode >> 8 & 0xF) << 1);
op2 = BarrelShifter.rotateRight(S, &cpu.cpsr, opcode & 0xFF, amount);
op2 = shifter.rotateRight(S, &cpu.cpsr, opcode & 0xFF, amount);
} else {
op2 = BarrelShifter.exec(S, cpu, opcode);
op2 = shifter.execute(S, cpu, opcode);
}
switch (instrKind) {
@@ -77,7 +70,7 @@ pub fn dataProcessing(comptime I: bool, comptime S: bool, comptime instrKind: u4
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
// Barrel Shifter should always calc CPSR C in TST
if (!S) _ = BarrelShifter.exec(true, cpu, opcode);
if (!S) _ = shifter.execute(true, cpu, opcode);
},
0x9 => {
// TEQ
@@ -86,7 +79,7 @@ pub fn dataProcessing(comptime I: bool, comptime S: bool, comptime instrKind: u4
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
// Barrel Shifter should always calc CPSR C in TEQ
if (!S) _ = BarrelShifter.exec(true, cpu, opcode);
if (!S) _ = shifter.execute(true, cpu, opcode);
},
0xD => {
// MOV