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fix: reimpl THUMB.5 instructions 

pipeline branch now passes arm.gba and thumb.gba again

(TODO: Stop rewriting my commits away)
This commit is contained in:
Rekai Nyangadzayi Musuka 2022-08-26 20:44:26 -05:00
parent e0a35ae273
commit e9e319209a
1 changed files with 15 additions and 16 deletions
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31
src/core/cpu/thumb/data_processing.zig
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@ -10,8 +10,6 @@ const sub = @import("../arm/data_processing.zig").sub;
const cmp = @import("../arm/data_processing.zig").cmp;
const setLogicOpFlags = @import("../arm/data_processing.zig").setLogicOpFlags;
const log = std.log.scoped(.Thumb1);
pub fn fmt1(comptime op: u2, comptime offset: u5) InstrFn {
return struct {
fn inner(cpu: *Arm7tdmi, _: *Bus, opcode: u16) void {
@ -58,37 +56,38 @@ pub fn fmt1(comptime op: u2, comptime offset: u5) InstrFn {
pub fn fmt5(comptime op: u2, comptime h1: u1, comptime h2: u1) InstrFn {
return struct {
fn inner(cpu: *Arm7tdmi, _: *Bus, opcode: u16) void {
const src_idx = @as(u4, h2) << 3 | (opcode >> 3 & 0x7);
const dst_idx = @as(u4, h1) << 3 | (opcode & 0x7);
const rs = @as(u4, h2) << 3 | (opcode >> 3 & 0x7);
const rd = @as(u4, h1) << 3 | (opcode & 0x7);
const src = if (src_idx == 0xF) (cpu.r[src_idx] + 2) & 0xFFFF_FFFE else cpu.r[src_idx];
const dst = if (dst_idx == 0xF) (cpu.r[dst_idx] + 2) & 0xFFFF_FFFE else cpu.r[dst_idx];
const rs_value = if (rs == 0xF) cpu.r[rs] & ~@as(u32, 1) else cpu.r[rs];
const rd_value = if (rd == 0xF) cpu.r[rd] & ~@as(u32, 1) else cpu.r[rd];
switch (op) {
0b00 => {
// ADD
const sum = add(false, cpu, dst, src);
cpu.r[dst_idx] = if (dst_idx == 0xF) sum & 0xFFFF_FFFE else sum;
const sum = add(false, cpu, rd_value, rs_value);
cpu.r[rd] = if (rd == 0xF) sum & ~@as(u32, 1) else sum;
},
0b01 => cmp(cpu, dst, src), // CMP
0b01 => cmp(cpu, rd_value, rs_value), // CMP
0b10 => {
// MOV
cpu.r[dst_idx] = if (dst_idx == 0xF) src & 0xFFFF_FFFE else src;
cpu.r[rd] = if (rd == 0xF) rs_value & ~@as(u32, 1) else rs_value;
},
0b11 => {
// BX
const thumb = src & 1 == 1;
cpu.r[15] = src & ~@as(u32, 1);
cpu.cpsr.t.write(thumb);
const thumb = rs_value & 1 == 1;
cpu.r[15] = rs_value & ~@as(u32, 1);
cpu.cpsr.t.write(thumb);
if (thumb) cpu.pipe.reload(u16, cpu) else cpu.pipe.reload(u32, cpu);
// Pipeline alrady flushed
return; // FIXME: Is this necessary? (Refactor out?)
// TODO: We shouldn't need to worry about the if statement
// below, because in BX, rd SBZ (and H1 is guaranteed to be 0)
return;
},
}
if (dst_idx == 0xF) cpu.pipe.reload(u16, cpu);
if (rd == 0xF) cpu.pipe.reload(u16, cpu);
}
}.inner;
}