authorgravatar for thejoshwolfe@gmail.comJosh Wolfe <thejoshwolfe@gmail.com> 2018-11-07 20:50:10-05:00
committergravatar for thejoshwolfe@gmail.comJosh Wolfe <thejoshwolfe@gmail.com> 2018-11-14 20:57:46-05:00
log772876b2f0104953af56eccbd85b2b21c6e908ef
tree4d801087fcea436e57621fd2cdc30c6f9520fb1c
parent8d8836c2d1a5f2137867a01689021d3e6b1966ae

implement mem.writeIntLE, mem.writeIntBE

1 files changed, 80 insertions(+), 0 deletions(-)

std/mem.zig+80
...@@ -439,6 +439,7 @@ pub fn readIntBE(comptime T: type, bytes: []const u8) T {...@@ -439,6 +439,7 @@ pub fn readIntBE(comptime T: type, bytes: []const u8) T {
439 return @bitCast(T, readIntBE(@IntType(false, T.bit_count), bytes));439 return @bitCast(T, readIntBE(@IntType(false, T.bit_count), bytes));
440 }440 }
441 assert(bytes.len == @sizeOf(T));441 assert(bytes.len == @sizeOf(T));
442 if (T == u8) return bytes[0];
442 var result: T = 0;443 var result: T = 0;
443 {444 {
444 comptime var i = 0;445 comptime var i = 0;
...@@ -456,6 +457,7 @@ pub fn readIntLE(comptime T: type, bytes: []const u8) T {...@@ -456,6 +457,7 @@ pub fn readIntLE(comptime T: type, bytes: []const u8) T {
456 return @bitCast(T, readIntLE(@IntType(false, T.bit_count), bytes));457 return @bitCast(T, readIntLE(@IntType(false, T.bit_count), bytes));
457 }458 }
458 assert(bytes.len == @sizeOf(T));459 assert(bytes.len == @sizeOf(T));
460 if (T == u8) return bytes[0];
459 var result: T = 0;461 var result: T = 0;
460 {462 {
461 comptime var i = 0;463 comptime var i = 0;
...@@ -492,6 +494,84 @@ pub fn writeInt(buf: []u8, value: var, endian: builtin.Endian) void {...@@ -492,6 +494,84 @@ pub fn writeInt(buf: []u8, value: var, endian: builtin.Endian) void {
492 assert(bits == 0);494 assert(bits == 0);
493}495}
494496
497pub fn writeIntBE(comptime T: type, buf: *[@sizeOf(T)]u8, value: T) void {
498 assert(T.bit_count % 8 == 0);
499 const uint = @IntType(false, T.bit_count);
500 if (uint == u0) {
501 return;
502 }
503 var bits = @bitCast(uint, value);
504 if (uint == u8) {
505 buf[0] = bits;
506 return;
507 }
508 var index: usize = buf.len;
509 while (index != 0) {
510 index -= 1;
511
512 buf[index] = @truncate(u8, bits);
513 bits >>= 8;
514 }
515 assert(bits == 0);
516}
517
518pub fn writeIntLE(comptime T: type, buf: *[@sizeOf(T)]u8, value: T) void {
519 assert(T.bit_count % 8 == 0);
520 const uint = @IntType(false, T.bit_count);
521 if (uint == u0) {
522 return;
523 }
524 var bits = @bitCast(uint, value);
525 if (uint == u8) {
526 buf[0] = bits;
527 return;
528 }
529 // FIXME: this should just be for (buf).
530 // See https://github.com/ziglang/zig/issues/1663
531 for (buf.*) |*b| {
532 b.* = @truncate(u8, bits);
533 bits >>= 8;
534 }
535 assert(bits == 0);
536}
537
538test "writeIntBE/LE" {
539 var buf0: [0]u8 = undefined;
540 var buf1: [1]u8 = undefined;
541 var buf2: [2]u8 = undefined;
542 var buf9: [9]u8 = undefined;
543
544 writeIntBE(u0, &buf0, 0x0);
545 assert(eql_slice_u8(buf0[0..], []u8{}));
546 writeIntLE(u0, &buf0, 0x0);
547 assert(eql_slice_u8(buf0[0..], []u8{}));
548
549 writeIntBE(u8, &buf1, 0x12);
550 assert(eql_slice_u8(buf1[0..], []u8{0x12}));
551 writeIntLE(u8, &buf1, 0x34);
552 assert(eql_slice_u8(buf1[0..], []u8{0x34}));
553
554 writeIntBE(u16, &buf2, 0x1234);
555 assert(eql_slice_u8(buf2[0..], []u8{ 0x12, 0x34 }));
556 writeIntLE(u16, &buf2, 0x5678);
557 assert(eql_slice_u8(buf2[0..], []u8{ 0x78, 0x56 }));
558
559 writeIntBE(u72, &buf9, 0x123456789abcdef024);
560 assert(eql_slice_u8(buf9[0..], []u8{ 0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0, 0x24 }));
561 writeIntLE(u72, &buf9, 0xfedcba9876543210ec);
562 assert(eql_slice_u8(buf9[0..], []u8{ 0xec, 0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe }));
563
564 writeIntBE(i8, &buf1, -1);
565 assert(eql_slice_u8(buf1[0..], []u8{0xff}));
566 writeIntLE(i8, &buf1, -2);
567 assert(eql_slice_u8(buf1[0..], []u8{0xfe}));
568
569 writeIntBE(i16, &buf2, -3);
570 assert(eql_slice_u8(buf2[0..], []u8{ 0xff, 0xfd }));
571 writeIntLE(i16, &buf2, -4);
572 assert(eql_slice_u8(buf2[0..], []u8{ 0xfc, 0xff }));
573}
574
495pub fn hash_slice_u8(k: []const u8) u32 {575pub fn hash_slice_u8(k: []const u8) u32 {
496 // FNV 32-bit hash576 // FNV 32-bit hash
497 var h: u32 = 2166136261;577 var h: u32 = 2166136261;