mirror/zig
1
0
Fork 0
mirror of https://github.com/ziglang/zig.git synced 2026-02-14 21:38:33 +00:00
Code Issues Packages Projects Releases Wiki Activity

add mem.readIntLE and readIntBE

Browse Source
This commit is contained in:
Josh Wolfe 2017-11-30 11:20:39 -07:00
parent 210d0017c4
commit 5786df933d
1 changed files with 41 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
std/mem.zig
View File

@ -180,6 +180,7 @@ test "mem.indexOf" {
/// Reads an integer from memory with size equal to bytes.len.
/// T specifies the return type, which must be large enough to store
/// the result.
/// See also ::readIntBE or ::readIntLE.
pub fn readInt(bytes: []const u8, comptime T: type, big_endian: bool) -> T {
if (T.bit_count == 8) {
return bytes[0];
@ -198,6 +199,34 @@ pub fn readInt(bytes: []const u8, comptime T: type, big_endian: bool) -> T {
return result;
}
/// Reads a big-endian int of type T from bytes.
/// bytes.len must be exactly @sizeOf(T).
pub fn readIntBE(comptime T: type, bytes: []const u8) -> T {
if (T.is_signed) {
return @bitCast(T, readIntBE(@IntType(false, T.bit_count), bytes));
}
assert(bytes.len == @sizeOf(T));
var result: T = 0;
{comptime var i = 0; inline while (i < @sizeOf(T)) : (i += 1) {
result = (result << 8) | T(bytes[i]);
}}
return result;
}
/// Reads a little-endian int of type T from bytes.
/// bytes.len must be exactly @sizeOf(T).
pub fn readIntLE(comptime T: type, bytes: []const u8) -> T {
if (T.is_signed) {
return @bitCast(T, readIntLE(@IntType(false, T.bit_count), bytes));
}
assert(bytes.len == @sizeOf(T));
var result: T = 0;
{comptime var i = 0; inline while (i < @sizeOf(T)) : (i += 1) {
result |= T(bytes[i]) << i * 8;
}}
return result;
}
/// Writes an integer to memory with size equal to bytes.len. Pads with zeroes
/// to fill the entire buffer provided.
/// value must be an integer.
@ -348,8 +377,12 @@ test "testReadInt" {
fn testReadIntImpl() {
{
const bytes = []u8{ 0x12, 0x34, 0x56, 0x78 };
assert(readInt(bytes, u32, true) == 0x12345678);
assert(readInt(bytes, u32, true) == 0x12345678);
assert(readIntBE(u32, bytes) == 0x12345678);
assert(readIntBE(i32, bytes) == 0x12345678);
assert(readInt(bytes, u32, false) == 0x78563412);
assert(readIntLE(u32, bytes) == 0x78563412);
assert(readIntLE(i32, bytes) == 0x78563412);
}
{
const buf = []u8{0x00, 0x00, 0x12, 0x34};
@ -361,6 +394,13 @@ fn testReadIntImpl() {
const answer = readInt(buf, u64, false);
assert(answer == 0x00003412);
}
{
const bytes = []u8{0xff, 0xfe};
assert(readIntBE(u16, bytes) == 0xfffe);
assert(readIntBE(i16, bytes) == -0x0002);
assert(readIntLE(u16, bytes) == 0xfeff);
assert(readIntLE(i16, bytes) == -0x0101);
}
}
test "testWriteInt" {