112 lines
3.6 KiB
Zig
112 lines
3.6 KiB
Zig
const Bus = @import("../../Bus.zig");
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const Arm7tdmi = @import("../../cpu.zig").Arm7tdmi;
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const InstrFn = @import("../../cpu.zig").arm.InstrFn;
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pub fn blockDataTransfer(comptime P: bool, comptime U: bool, comptime S: bool, comptime W: bool, comptime L: bool) InstrFn {
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return struct {
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fn inner(cpu: *Arm7tdmi, bus: *Bus, opcode: u32) void {
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const rn = @truncate(u4, opcode >> 16 & 0xF);
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const rlist = opcode & 0xFFFF;
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const r15 = rlist >> 15 & 1 == 1;
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var count: u32 = 0;
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var i: u5 = 0;
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var first: u4 = 0;
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var write_to_base = true;
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while (i < 16) : (i += 1) {
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const r = @truncate(u4, 15 - i);
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if (rlist >> r & 1 == 1) {
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first = r;
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count += 1;
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}
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}
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var start = cpu.r[rn];
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if (U) {
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start += if (P) 4 else 0;
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} else {
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start = start - (4 * count) + if (!P) 4 else 0;
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}
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var end = cpu.r[rn];
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if (U) {
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end = end + (4 * count) - if (!P) 4 else 0;
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} else {
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end -= if (P) 4 else 0;
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}
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var new_base = cpu.r[rn];
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if (U) {
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new_base += 4 * count;
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} else {
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new_base -= 4 * count;
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}
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var address = start;
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if (rlist == 0) {
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var und_addr = cpu.r[rn];
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if (U) {
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und_addr += if (P) 4 else 0;
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} else {
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und_addr -= 0x40 - if (!P) 4 else 0;
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}
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if (L) {
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cpu.r[15] = bus.read(u32, und_addr);
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cpu.pipe.reload(cpu);
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} else {
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bus.write(u32, und_addr, cpu.r[15] + 4);
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}
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cpu.r[rn] = if (U) cpu.r[rn] + 0x40 else cpu.r[rn] - 0x40;
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return;
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}
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i = first;
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while (i < 16) : (i += 1) {
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if (rlist >> i & 1 == 1) {
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transfer(cpu, bus, r15, i, address);
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address += 4;
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if (W and !L and write_to_base) {
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cpu.r[rn] = new_base;
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write_to_base = false;
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}
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}
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}
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if (W and L and rlist >> rn & 1 == 0) cpu.r[rn] = new_base;
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}
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fn transfer(cpu: *Arm7tdmi, bus: *Bus, r15_present: bool, i: u5, address: u32) void {
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if (L) {
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if (S and !r15_present) {
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// Always Transfer User mode Registers
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cpu.setUserModeRegister(i, bus.read(u32, address));
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} else {
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const value = bus.read(u32, address);
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cpu.r[i] = value;
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if (i == 0xF) {
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cpu.r[i] &= ~@as(u32, 3); // Align r15
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cpu.pipe.reload(cpu);
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if (S) cpu.setCpsr(cpu.spsr.raw);
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}
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}
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} else {
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if (S) {
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// Always Transfer User mode Registers
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// This happens regardless if r15 is in the list
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const value = cpu.getUserModeRegister(i);
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bus.write(u32, address, value + if (i == 0xF) 4 else @as(u32, 0)); // PC is already 8 ahead to make 12
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} else {
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bus.write(u32, address, cpu.r[i] + if (i == 0xF) 4 else @as(u32, 0));
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}
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}
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}
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}.inner;
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}
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