37 lines
1.2 KiB
Zig
37 lines
1.2 KiB
Zig
const std = @import("std");
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const Bus = @import("../../Bus.zig");
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const Arm7tdmi = @import("../../cpu.zig").Arm7tdmi;
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const InstrFn = @import("../../cpu.zig").ThumbInstrFn;
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pub fn format9(comptime B: bool, comptime L: bool, comptime offset: u5) InstrFn {
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return struct {
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fn inner(cpu: *Arm7tdmi, bus: *Bus, opcode: u16) void {
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const rb = opcode >> 3 & 0x7;
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const rd = opcode & 0x7;
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if (L) {
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if (B) {
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// LDRB
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const address = cpu.r[rb] + offset;
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cpu.r[rd] = bus.read8(address);
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} else {
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// LDR
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const address = cpu.r[rb] + (@as(u32, offset) << 2);
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cpu.r[rd] = bus.read32(address & 0xFFFF_FFFC);
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}
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} else {
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if (B) {
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// STRB
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const address = cpu.r[rb] + offset;
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bus.write8(address, @truncate(u8, cpu.r[rd]));
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} else {
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// STR
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const address = cpu.r[rb] + (@as(u32, offset) << 2);
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bus.write32(address & 0xFFFF_FFFC, cpu.r[rd]);
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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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