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link+riscv: use riscv64/bits.zig to implement write helpers

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This commit is contained in:
Jakub Konka 2024-02-21 23:25:49 +01:00
parent ddb33baa11
commit 2ad2e2f6f5
1 changed files with 28 additions and 16 deletions
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44
src/link/riscv.zig
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@ -25,34 +25,46 @@ pub fn writeAddend(
}
pub fn writeInstU(code: *[4]u8, value: u32) void {
const inst_mask: u32 = 0b00000000000000000000_11111_1111111;
const val_mask: u32 = 0xffff_f000;
var inst = mem.readInt(u32, code, .little);
inst &= inst_mask;
var inst = Instruction{
.U = mem.bytesToValue(std.meta.TagPayload(
Instruction,
Instruction.U,
), code),
};
const compensated: u32 = @bitCast(@as(i32, @bitCast(value)) + 0x800);
inst |= (compensated & val_mask);
mem.writeInt(u32, code, inst, .little);
inst.U.imm12_31 = @truncate(bitSlice(compensated, 31, 12));
mem.writeInt(u32, code, inst.toU32(), .little);
}
pub fn writeInstI(code: *[4]u8, value: u32) void {
const mask: u32 = 0b00000000000_11111_111_11111_1111111;
var inst = mem.readInt(u32, code, .little);
inst &= mask;
inst |= (bitSlice(value, 11, 0) << 20);
mem.writeInt(u32, code, inst, .little);
var inst = Instruction{
.I = mem.bytesToValue(std.meta.TagPayload(
Instruction,
Instruction.I,
), code),
};
inst.I.imm0_11 = @truncate(bitSlice(value, 11, 0));
mem.writeInt(u32, code, inst.toU32(), .little);
}
pub fn writeInstS(code: *[4]u8, value: u32) void {
const mask: u32 = 0b000000_11111_11111_111_00000_1111111;
var inst = mem.readInt(u32, code, .little);
inst &= mask;
inst |= (bitSlice(value, 11, 5) << 25) | (bitSlice(value, 4, 0) << 7);
mem.writeInt(u32, code, inst, .little);
var inst = Instruction{
.S = mem.bytesToValue(std.meta.TagPayload(
Instruction,
Instruction.S,
), code),
};
inst.S.imm0_4 = @truncate(bitSlice(value, 4, 0));
inst.S.imm5_11 = @truncate(bitSlice(value, 11, 5));
mem.writeInt(u32, code, inst.toU32(), .little);
}
fn bitSlice(value: anytype, high: std.math.Log2Int(@TypeOf(value)), low: std.math.Log2Int(@TypeOf(value))) @TypeOf(value) {
return (value >> low) & ((@as(@TypeOf(value), 1) << (high - low + 1)) - 1);
}
const bits = @import("../arch/riscv64/bits.zig");
const mem = std.mem;
const std = @import("std");
pub const Instruction = bits.Instruction;