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feat(cpu): implement ARM SWP and SWPB

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This commit is contained in:
Rekai Nyangadzayi Musuka
2022-02-02 08:44:33 -04:00
parent 6c7934be70
commit c34c2ee6eb
3 changed files with 77 additions and 52 deletions
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89
src/cpu.zig
View File

@@ -19,6 +19,7 @@ const branchAndExchange = @import("cpu/arm/branch.zig").branchAndExchange;
const softwareInterrupt = @import("cpu/arm/software_interrupt.zig").softwareInterrupt;
const multiply = @import("cpu/arm/multiply.zig").multiply;
const multiplyLong = @import("cpu/arm/multiply_long.zig").multiplyLong;
const singleDataSwap = @import("cpu/arm/single_data_swap.zig").singleDataSwap;
// THUMB Instruction Groups
const format1 = @import("cpu/thumb/format1.zig").format1;
@@ -491,33 +492,35 @@ fn thumbPopulate() [0x400]ThumbInstrFn {
fn armPopulate() [0x1000]ArmInstrFn {
return comptime {
@setEvalBranchQuota(0x5000); // TODO: Figure out exact size
@setEvalBranchQuota(0xC000); // TODO: Figure out exact size
var lut = [_]ArmInstrFn{armUndefined} ** 0x1000;
var i: usize = 0;
while (i < lut.len) : (i += 1) {
if (i >> 10 & 0x3 == 0b00) {
const I = i >> 9 & 1 == 1;
const S = i >> 4 & 1 == 1;
const instrKind = i >> 5 & 0xF;
lut[i] = dataProcessing(I, S, instrKind);
}
if (i >> 10 & 0x3 == 0b00 and i >> 7 & 0x3 == 0b10 and i >> 4 & 1 == 0) {
// PSR Transfer
const I = i >> 9 & 1 == 1;
const R = i >> 6 & 1 == 1;
const kind = i >> 4 & 0x3;
lut[i] = psrTransfer(I, R, kind);
}
// Instructions with Opcode[27] == 0
if (i == 0x121) {
// Bits 27:20 and 7:4
lut[i] = branchAndExchange;
}
} else if (i >> 6 & 0x3F == 0b000000 and i & 0xF == 0b1001) {
// Bits 27:22 and 7:4
const A = i >> 5 & 1 == 1;
const S = i >> 4 & 1 == 1;
if (i >> 9 & 0x7 == 0b000 and i >> 3 & 1 == 1 and i & 1 == 1) {
lut[i] = multiply(A, S);
} else if (i >> 7 & 0x1F == 0b00010 and i >> 4 & 0x3 == 0b00 and i & 0xF == 0b1001) {
// Bits 27:23, 21:20 and 7:4
const B = i >> 6 & 1 == 1;
lut[i] = singleDataSwap(B);
} else if (i >> 7 & 0x1F == 0b00001 and i & 0xF == 0b1001) {
// Bits 27:23 and bits 7:4
const U = i >> 6 & 1 == 1;
const A = i >> 5 & 1 == 1;
const S = i >> 4 & 1 == 1;
lut[i] = multiplyLong(U, A, S);
} else if (i >> 9 & 0x7 == 0b000 and i >> 3 & 1 == 1 and i & 1 == 1) {
// Bits 27:25, 7 and 4
const P = i >> 8 & 1 == 1;
const U = i >> 7 & 1 == 1;
const I = i >> 6 & 1 == 1;
@@ -525,24 +528,18 @@ fn armPopulate() [0x1000]ArmInstrFn {
const L = i >> 4 & 1 == 1;
lut[i] = halfAndSignedDataTransfer(P, U, I, W, L);
}
} else if (i >> 9 & 0x7 == 0b011 and i & 1 == 1) {
// Bits 27:25 and 4
lut[i] = armUndefined;
} else if (i >> 10 & 0x3 == 0b00 and i >> 7 & 0x3 == 0b10 and i >> 4 & 1 == 0) {
// Bits 27:26, 24:23 and 20
const I = i >> 9 & 1 == 1;
const R = i >> 6 & 1 == 1;
const kind = i >> 4 & 0x3;
if (i >> 6 & 0x3F == 0b000000 and i & 0xF == 0b1001) {
const A = i >> 5 & 1 == 1;
const S = i >> 4 & 1 == 1;
lut[i] = multiply(A, S);
}
if (i >> 7 & 0x1F == 0b00001 and i & 0xF == 0b1001) {
const U = i >> 6 & 1 == 1;
const A = i >> 5 & 1 == 1;
const S = i >> 4 & 1 == 1;
lut[i] = multiplyLong(U, A, S);
}
if (i >> 10 & 0x3 == 0b01) {
lut[i] = psrTransfer(I, R, kind);
} else if (i >> 10 & 0x3 == 0b01) {
// Bits 27:26
const I = i >> 9 & 1 == 1;
const P = i >> 8 & 1 == 1;
const U = i >> 7 & 1 == 1;
@@ -551,9 +548,18 @@ fn armPopulate() [0x1000]ArmInstrFn {
const L = i >> 4 & 1 == 1;
lut[i] = singleDataTransfer(I, P, U, B, W, L);
} else if (i >> 10 & 0x3 == 0b00) {
// Bits 27:26
const I = i >> 9 & 1 == 1;
const S = i >> 4 & 1 == 1;
const instrKind = i >> 5 & 0xF;
lut[i] = dataProcessing(I, S, instrKind);
}
// Instructions with Opcode[27] == 1
if (i >> 9 & 0x7 == 0b100) {
// Bits 27:25
const P = i >> 8 & 1 == 1;
const U = i >> 7 & 1 == 1;
const S = i >> 6 & 1 == 1;
@@ -561,14 +567,11 @@ fn armPopulate() [0x1000]ArmInstrFn {
const L = i >> 4 & 1 == 1;
lut[i] = blockDataTransfer(P, U, S, W, L);
}
if (i >> 9 & 0x7 == 0b101) {
} else if (i >> 9 & 0x7 == 0b101) {
// Bits 27:25
const L = i >> 8 & 1 == 1;
lut[i] = branch(L);
}
if (i >> 8 & 0xF == 0b1111) lut[i] = softwareInterrupt();
} else if (i >> 8 & 0xF == 0b1111) lut[i] = softwareInterrupt(); // Bits 27:24
}
return lut;

11
src/cpu/arm/half_signed_data_transfer.zig
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@@ -33,12 +33,6 @@ pub fn halfAndSignedDataTransfer(comptime P: bool, comptime U: bool, comptime I:
if (L) {
switch (@truncate(u2, opcode >> 5)) {
0b00 => {
// SWP
const value = bus.read32(cpu.r[rn]);
const tmp = std.math.rotr(u32, value, 8 * (cpu.r[rn] & 0x3));
bus.write32(cpu.r[rm], tmp);
},
0b01 => {
// LDRH
const value = bus.read16(address & 0xFFFF_FFFE);
@@ -54,14 +48,13 @@ pub fn halfAndSignedDataTransfer(comptime P: bool, comptime U: bool, comptime I:
cpu.r[rd] = util.u32SignExtend(16, @as(u32, bus.read16(address)));
cpu.panic("[CPU|ARM|LDRSH] TODO: Affect the CPSR", .{});
},
0b00 => unreachable, // SWP
}
} else {
if (opcode >> 5 & 0x01 == 0x01) {
// STRH
bus.write16(address, @truncate(u16, cpu.r[rd]));
} else {
std.debug.print("[CPU|ARM|SignedDataTransfer] {X:0>8} was improperly decoded", .{opcode});
}
} else unreachable; // SWP
}
address = modified_base;

29
src/cpu/arm/single_data_swap.zig Normal file
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@@ -0,0 +1,29 @@
const std = @import("std");
const Bus = @import("../../Bus.zig");
const Arm7tdmi = @import("../../cpu.zig").Arm7tdmi;
const InstrFn = @import("../../cpu.zig").ArmInstrFn;
pub fn singleDataSwap(comptime B: bool) InstrFn {
return struct {
fn inner(cpu: *Arm7tdmi, bus: *Bus, opcode: u32) void {
const rn = opcode >> 16 & 0xF;
const rd = opcode >> 12 & 0xF;
const rm = opcode & 0xF;
const address = cpu.r[rn];
if (B) {
// SWPB
const value = bus.read8(address);
bus.write8(address, @truncate(u8, cpu.r[rm]));
cpu.r[rd] = value;
} else {
// SWP
const value = std.math.rotr(u32, bus.read32(address), 8 * (address & 0x3));
bus.write32(address, cpu.r[rm]);
cpu.r[rd] = value;
}
}
}.inner;
}