114 lines
3.1 KiB
Zig
114 lines
3.1 KiB
Zig
const SYS_write : usize = 1;
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const SYS_exit : usize = 60;
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const SYS_getrandom : usize = 318;
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fn syscall1(number: usize, arg1: usize) -> usize {
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asm volatile ("syscall"
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: [ret] "={rax}" (-> usize)
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: [number] "{rax}" (number), [arg1] "{rdi}" (arg1)
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: "rcx", "r11")
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}
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fn syscall3(number: usize, arg1: usize, arg2: usize, arg3: usize) -> usize {
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asm volatile ("syscall"
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: [ret] "={rax}" (-> usize)
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: [number] "{rax}" (number), [arg1] "{rdi}" (arg1), [arg2] "{rsi}" (arg2), [arg3] "{rdx}" (arg3)
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: "rcx", "r11")
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}
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pub fn write(fd: isize, buf: &const u8, count: usize) -> isize {
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syscall3(SYS_write, fd as usize, buf as usize, count) as isize
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}
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pub fn exit(status: i32) -> unreachable {
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syscall1(SYS_exit, status as usize);
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unreachable
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}
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pub fn getrandom(buf: &u8, count: usize, flags: u32) -> isize {
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syscall3(SYS_getrandom, buf as usize, count, flags as usize) as isize
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}
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const stdout_fileno : isize = 1;
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const stderr_fileno : isize = 2;
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// TODO error handling
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pub fn os_get_random_bytes(buf: &u8, count: usize) -> isize {
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getrandom(buf, count, 0)
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}
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// TODO error handling
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// TODO handle buffering and flushing (mutex protected)
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pub fn print_str(str: []const u8) -> isize {
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fprint_str(stdout_fileno, str)
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}
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// TODO error handling
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// TODO handle buffering and flushing (mutex protected)
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pub fn fprint_str(fd: isize, str: []const u8) -> isize {
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write(fd, str.ptr, str.len)
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}
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// TODO handle buffering and flushing (mutex protected)
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// TODO error handling
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pub fn print_u64(x: u64) -> isize {
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// TODO use max_u64_base10_digits instead of hardcoding 20
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var buf: [20]u8;
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const len = buf_print_u64(buf.ptr, x);
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return write(stdout_fileno, buf.ptr, len);
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}
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// TODO handle buffering and flushing (mutex protected)
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// TODO error handling
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pub fn print_i64(x: i64) -> isize {
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// TODO use max_u64_base10_digits instead of hardcoding 20
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var buf: [20]u8;
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const len = buf_print_i64(buf.ptr, x);
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return write(stdout_fileno, buf.ptr, len);
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}
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fn digit_to_char(digit: u64) -> u8 {
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'0' + (digit as u8)
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}
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const max_u64_base10_digits: usize = 20;
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// TODO use an array for out_buf instead of pointer. this should give bounds checking in
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// debug mode and length can get optimized out in release mode. requires array slicing syntax
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// for the buf_print_u64 call.
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fn buf_print_i64(out_buf: &u8, x: i64) -> usize {
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if (x < 0) {
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out_buf[0] = '-';
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return 1 + buf_print_u64(&out_buf[1], ((-(x + 1)) as u64) + 1);
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} else {
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return buf_print_u64(out_buf, x as u64);
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}
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}
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// TODO use an array for out_buf instead of pointer.
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fn buf_print_u64(out_buf: &u8, x: u64) -> usize {
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var buf: [max_u64_base10_digits]u8;
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var a = x;
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var index = buf.len;
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while (true) {
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const digit = a % 10;
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index -= 1;
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buf[index] = digit_to_char(digit);
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a /= 10;
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if (a == 0)
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break;
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}
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const len = buf.len - index;
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// TODO memcpy intrinsic
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var i: usize = 0;
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while (i < len) {
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out_buf[i] = buf[index + i];
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i += 1;
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}
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return len;
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}
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