incasm.zig

const std = @import("std");

fn comptimeBytes(comptime name: []const u8, comptime instructions: []const u8) []const u8 {\
    // won't compile with ".section .bss\n"
    asm volatile (".global " ++ name ++ ", " ++ name ++ "_end\njmp " ++ name ++ "_end\n" ++ name ++ ":\n" ++ instructions ++ "\n" ++ name ++ "_end:");
    const start = @extern(*const u8, .{ .name = name });
    const end = @extern(*const u8, .{ .name = name ++ "_end" });
    const size = @ptrToInt(end) - @ptrToInt(start);
    var result: []const u8 = undefined;
    result.ptr = @ptrCast([*]const u8, start);
    result.len = size;
    return result;
}

// Type your code here, or load an example.
pub fn main() !void {
    const syscall = comptimeBytes("syscall_bytes", "syscall");
    const xor_rax = comptimeBytes("xor_rax", "xor %%rax, %%rax");
    const out = std.io.getStdOut().writer();
    try out.print("syscall: {}\nxor rax: {}", .{
        std.fmt.fmtSliceHexLower(syscall),
        std.fmt.fmtSliceHexLower(xor_rax),
    });
}