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Better documentation, use of len field instead of function, @bitSizeOf instead of meta.bitCout

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tgschultz 2021-10-08 16:22:32 +00:00 committed by Andrew Kelley
parent 73403d897c
commit 526191bfaf
1 changed files with 109 additions and 116 deletions
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225
lib/std/packed_int_array.zig
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@ -1,3 +1,7 @@
//! An set of array and slice types that bit-pack integer elements. A normal [12]u3
//! takes up 12 bytes of memory since u3's alignment is 1. PackedArray(u3, 12) only
//! takes up 4 bytes of memory.
const std = @import("std");
const builtin = @import("builtin");
const debug = std.debug;
@ -5,8 +9,10 @@ const testing = std.testing;
const native_endian = builtin.target.cpu.arch.endian();
const Endian = std.builtin.Endian;
/// Provides a set of functions for reading and writing packed integers from a
/// slice of bytes.
pub fn PackedIntIo(comptime Int: type, comptime endian: Endian) type {
//The general technique employed here is to cast bytes in the array to a container
// The general technique employed here is to cast bytes in the array to a container
// integer (having bits % 8 == 0) large enough to contain the number of bits we want,
// then we can retrieve or store the new value with a relative minimum of masking
// and shifting. In this worst case, this means that we'll need an integer that's
@ -18,13 +24,13 @@ pub fn PackedIntIo(comptime Int: type, comptime endian: Endian) type {
// mean the OS fatally kills the program. Thus, we use a larger container (MaxIo)
// most of the time, but a smaller container (MinIo) when touching the last byte
// of the memory.
const int_bits = comptime std.meta.bitCount(Int);
const int_bits = @bitSizeOf(Int);
//in the best case, this is the number of bytes we need to touch
// to read or write a value, as bits
// In the best case, this is the number of bytes we need to touch
// to read or write a value, as bits.
const min_io_bits = ((int_bits + 7) / 8) * 8;
//in the worst case, this is the number of bytes we need to touch
// In the worst case, this is the number of bytes we need to touch
// to read or write a value, as bits. To calculate for int_bits > 1,
// set aside 2 bits to touch the first and last bytes, then divide
// by 8 to see how many bytes can be filled up inbetween.
@ -34,30 +40,32 @@ pub fn PackedIntIo(comptime Int: type, comptime endian: Endian) type {
else => ((int_bits - 2) / 8 + 2) * 8,
};
//we bitcast the desired Int type to an unsigned version of itself
// We bitcast the desired Int type to an unsigned version of itself
// to avoid issues with shifting signed ints.
const UnInt = std.meta.Int(.unsigned, int_bits);
//The maximum container int type
// The maximum container int type
const MinIo = std.meta.Int(.unsigned, min_io_bits);
//The minimum container int type
// The minimum container int type
const MaxIo = std.meta.Int(.unsigned, max_io_bits);
return struct {
/// Retrieves the integer at `index` from the packed data beginning at `bit_offset`
/// within `bytes`.
pub fn get(bytes: []const u8, index: usize, bit_offset: u7) Int {
if (int_bits == 0) return 0;
const bit_index = (index * int_bits) + bit_offset;
const max_end_byte = (bit_index + max_io_bits) / 8;
//Using the larger container size will potentially read out of bounds
//using the larger container size will potentially read out of bounds
if (max_end_byte > bytes.len) return getBits(bytes, MinIo, bit_index);
return getBits(bytes, MaxIo, bit_index);
}
fn getBits(bytes: []const u8, comptime Container: type, bit_index: usize) Int {
const container_bits = comptime std.meta.bitCount(Container);
const container_bits = @bitSizeOf(Container);
const Shift = std.math.Log2Int(Container);
const start_byte = bit_index / 8;
@ -86,19 +94,21 @@ pub fn PackedIntIo(comptime Int: type, comptime endian: Endian) type {
return @bitCast(Int, @truncate(UnInt, value));
}
/// Sets the integer at `index` to `val` within the packed data beginning
/// at `bit_offset` into `bytes`.
pub fn set(bytes: []u8, index: usize, bit_offset: u3, int: Int) void {
if (int_bits == 0) return;
const bit_index = (index * int_bits) + bit_offset;
const max_end_byte = (bit_index + max_io_bits) / 8;
//Using the larger container size will potentially write out of bounds
//using the larger container size will potentially write out of bounds
if (max_end_byte > bytes.len) return setBits(bytes, MinIo, bit_index, int);
setBits(bytes, MaxIo, bit_index, int);
}
fn setBits(bytes: []u8, comptime Container: type, bit_index: usize, int: Int) void {
const container_bits = comptime std.meta.bitCount(Container);
const container_bits = @bitSizeOf(Container);
const Shift = std.math.Log2Int(Container);
const start_byte = bit_index / 8;
@ -132,7 +142,9 @@ pub fn PackedIntIo(comptime Int: type, comptime endian: Endian) type {
target_ptr.* = target;
}
fn slice(bytes: []u8, bit_offset: u3, start: usize, end: usize) PackedIntSliceEndian(Int, endian) {
/// Provides a PackedIntSlice of the packed integers in `bytes` (which begins at `bit_offset`)
/// from the element specified by `start` to the element specified by `end`.
pub fn slice(bytes: []u8, bit_offset: u3, start: usize, end: usize) PackedIntSliceEndian(Int, endian) {
debug.assert(end >= start);
const length = end - start;
@ -148,8 +160,11 @@ pub fn PackedIntIo(comptime Int: type, comptime endian: Endian) type {
return new_slice;
}
fn sliceCast(bytes: []u8, comptime NewInt: type, comptime new_endian: Endian, bit_offset: u3, old_len: usize) PackedIntSliceEndian(NewInt, new_endian) {
const new_int_bits = comptime std.meta.bitCount(NewInt);
/// Recasts a packed slice to a version with elements of type `NewInt` and endianness `new_endian`.
/// Slice will begin at `bit_offset` within `bytes` and the new length will be automatically
/// calculated from `old_len` using the sizes of the current integer type and `NewInt`.
pub fn sliceCast(bytes: []u8, comptime NewInt: type, comptime new_endian: Endian, bit_offset: u3, old_len: usize) PackedIntSliceEndian(NewInt, new_endian) {
const new_int_bits = @bitSizeOf(NewInt);
const New = PackedIntSliceEndian(NewInt, new_endian);
const total_bits = (old_len * int_bits);
@ -165,18 +180,21 @@ pub fn PackedIntIo(comptime Int: type, comptime endian: Endian) type {
};
}
///Creates a bit-packed array of integers of type Int. Bits
/// are packed using native endianess and without storing any meta
/// data. PackedIntArray(i3, 8) will occupy exactly 3 bytes of memory.
/// Creates a bit-packed array of `Int`. Non-byte-multiple integers
/// will take up less memory in PackedIntArray than in a normal array.
/// Elements are packed using native endianess and without storing any
/// meta data. PackedArray(i3, 8) will occupy exactly 3 bytes
/// of memory.
pub fn PackedIntArray(comptime Int: type, comptime int_count: usize) type {
return PackedIntArrayEndian(Int, native_endian, int_count);
}
///Creates a bit-packed array of integers of type Int. Bits
/// are packed using specified endianess and without storing any meta
/// data.
/// Creates a bit-packed array of `Int` with bit order specified by `endian`.
/// Non-byte-multiple integers will take up less memory in PackedIntArrayEndian
/// than in a normal array. Elements are packed without storing any meta data.
/// PackedIntArrayEndian(i3, 8) will occupy exactly 3 bytes of memory.
pub fn PackedIntArrayEndian(comptime Int: type, comptime endian: Endian, comptime int_count: usize) type {
const int_bits = comptime std.meta.bitCount(Int);
const int_bits = @bitSizeOf(Int);
const total_bits = int_bits * int_count;
const total_bytes = (total_bits + 7) / 8;
@ -185,15 +203,12 @@ pub fn PackedIntArrayEndian(comptime Int: type, comptime endian: Endian, comptim
return struct {
const Self = @This();
/// The byte buffer containing the packed data.
bytes: [total_bytes]u8,
/// The number of elements in the packed array.
comptime len: usize = int_count,
///Returns the number of elements in the packed array
pub fn len(self: Self) usize {
_ = self;
return int_count;
}
///Initialize a packed array using an unpacked array
/// Initialize a packed array using an unpacked array
/// or, more likely, an array literal.
pub fn init(ints: [int_count]Int) Self {
var self = @as(Self, undefined);
@ -201,27 +216,27 @@ pub fn PackedIntArrayEndian(comptime Int: type, comptime endian: Endian, comptim
return self;
}
///Initialize all entries of a packed array to the same value
/// Initialize all entries of a packed array to the same value.
pub fn initAllTo(int: Int) Self {
// TODO: use `var self = @as(Self, undefined);` https://github.com/ziglang/zig/issues/7635
var self = Self{ .bytes = [_]u8{0} ** total_bytes };
var self = Self{ .bytes = [_]u8{0} ** total_bytes, .len = int_count };
self.setAll(int);
return self;
}
///Return the Int stored at index
/// Return the integer stored at `index`.
pub fn get(self: Self, index: usize) Int {
debug.assert(index < int_count);
return Io.get(&self.bytes, index, 0);
}
///Copy int into the array at index
///Copy the value of `int` into the array at `index`.
pub fn set(self: *Self, index: usize, int: Int) void {
debug.assert(index < int_count);
return Io.set(&self.bytes, index, 0, int);
}
///Set all entries of a packed array to the same value
/// Set all entries of a packed array to the value of `int`.
pub fn setAll(self: *Self, int: Int) void {
var i: usize = 0;
while (i < int_count) : (i += 1) {
@ -229,105 +244,96 @@ pub fn PackedIntArrayEndian(comptime Int: type, comptime endian: Endian, comptim
}
}
///Create a PackedIntSlice of the array from given start to given end
/// Create a PackedIntSlice of the array from `start` to `end`.
pub fn slice(self: *Self, start: usize, end: usize) PackedIntSliceEndian(Int, endian) {
debug.assert(start < int_count);
debug.assert(end <= int_count);
return Io.slice(&self.bytes, 0, start, end);
}
///Create a PackedIntSlice of the array using NewInt as the bit width integer.
/// NewInt's bit width must fit evenly within the array's Int's total bits.
/// Create a PackedIntSlice of the array using `NewInt` as the integer type.
/// `NewInt`'s bit width must fit evenly within the array's `Int`'s total bits.
pub fn sliceCast(self: *Self, comptime NewInt: type) PackedIntSlice(NewInt) {
return self.sliceCastEndian(NewInt, endian);
}
///Create a PackedIntSlice of the array using NewInt as the bit width integer
/// and new_endian as the new endianess. NewInt's bit width must fit evenly within
/// the array's Int's total bits.
/// Create a PackedIntSliceEndian of the array using `NewInt` as the integer type
/// and `new_endian` as the new endianess. `NewInt`'s bit width must fit evenly
/// within the array's `Int`'s total bits.
pub fn sliceCastEndian(self: *Self, comptime NewInt: type, comptime new_endian: Endian) PackedIntSliceEndian(NewInt, new_endian) {
return Io.sliceCast(&self.bytes, NewInt, new_endian, 0, int_count);
}
};
}
///Uses a slice as a bit-packed block of int_count integers of type Int.
/// Bits are packed using native endianess and without storing any meta
/// data.
/// A type representing a sub range of a PackedIntArray.
pub fn PackedIntSlice(comptime Int: type) type {
return PackedIntSliceEndian(Int, native_endian);
}
///Uses a slice as a bit-packed block of int_count integers of type Int.
/// Bits are packed using specified endianess and without storing any meta
/// data.
/// A type representing a sub range of a PackedIntArrayEndian.
pub fn PackedIntSliceEndian(comptime Int: type, comptime endian: Endian) type {
const int_bits = comptime std.meta.bitCount(Int);
const int_bits = @bitSizeOf(Int);
const Io = PackedIntIo(Int, endian);
return struct {
const Self = @This();
bytes: []u8,
int_count: usize,
bit_offset: u3,
len: usize,
///Returns the number of elements in the packed slice
pub fn len(self: Self) usize {
return self.int_count;
}
///Calculates the number of bytes required to store a desired count
/// of Ints
/// Calculates the number of bytes required to store a desired count
/// of `Int`s.
pub fn bytesRequired(int_count: usize) usize {
const total_bits = int_bits * int_count;
const total_bytes = (total_bits + 7) / 8;
return total_bytes;
}
///Initialize a packed slice using the memory at bytes, with int_count
/// elements. bytes must be large enough to accomodate the requested
/// Initialize a packed slice using the memory at `bytes`, with `int_count`
/// elements. `bytes` must be large enough to accomodate the requested
/// count.
pub fn init(bytes: []u8, int_count: usize) Self {
debug.assert(bytes.len >= bytesRequired(int_count));
return Self{
.bytes = bytes,
.int_count = int_count,
.len = int_count,
.bit_offset = 0,
};
}
///Return the Int stored at index
/// Return the integer stored at `index`.
pub fn get(self: Self, index: usize) Int {
debug.assert(index < self.int_count);
debug.assert(index < self.len);
return Io.get(self.bytes, index, self.bit_offset);
}
///Copy int into the array at index
/// Copy `int` into the slice at `index`.
pub fn set(self: *Self, index: usize, int: Int) void {
debug.assert(index < self.int_count);
debug.assert(index < self.len);
return Io.set(self.bytes, index, self.bit_offset, int);
}
///Create a PackedIntSlice of this slice from given start to given end
/// Create a PackedIntSlice of this slice from `start` to `end`.
pub fn slice(self: Self, start: usize, end: usize) PackedIntSliceEndian(Int, endian) {
debug.assert(start < self.int_count);
debug.assert(end <= self.int_count);
debug.assert(start < self.len);
debug.assert(end <= self.len);
return Io.slice(self.bytes, self.bit_offset, start, end);
}
///Create a PackedIntSlice of this slice using NewInt as the bit width integer.
/// NewInt's bit width must fit evenly within this slice's Int's total bits.
/// Create a PackedIntSlice of the sclice using `NewInt` as the integer type.
/// `NewInt`'s bit width must fit evenly within the slice's `Int`'s total bits.
pub fn sliceCast(self: Self, comptime NewInt: type) PackedIntSliceEndian(NewInt, endian) {
return self.sliceCastEndian(NewInt, endian);
}
///Create a PackedIntSlice of this slice using NewInt as the bit width integer
/// and new_endian as the new endianess. NewInt's bit width must fit evenly within
/// this slice's Int's total bits.
/// Create a PackedIntSliceEndian of the slice using `NewInt` as the integer type
/// and `new_endian` as the new endianess. `NewInt`'s bit width must fit evenly
/// within the slice's `Int`'s total bits.
pub fn sliceCastEndian(self: Self, comptime NewInt: type, comptime new_endian: Endian) PackedIntSliceEndian(NewInt, new_endian) {
return Io.sliceCast(self.bytes, NewInt, new_endian, self.bit_offset, self.int_count);
return Io.sliceCast(self.bytes, NewInt, new_endian, self.bit_offset, self.len);
}
};
}
@ -358,7 +364,7 @@ test "PackedIntArray" {
//write values, counting up
var i = @as(usize, 0);
var count = @as(I, 0);
while (i < data.len()) : (i += 1) {
while (i < data.len) : (i += 1) {
data.set(i, count);
if (bits > 0) count +%= 1;
}
@ -366,7 +372,7 @@ test "PackedIntArray" {
//read and verify values
i = 0;
count = 0;
while (i < data.len()) : (i += 1) {
while (i < data.len) : (i += 1) {
const val = data.get(i);
try testing.expect(val == count);
if (bits > 0) count +%= 1;
@ -383,19 +389,17 @@ test "PackedIntIo" {
}
test "PackedIntArray init" {
if (we_are_testing_this_with_stage1_which_leaks_comptime_memory) return error.SkipZigTest;
const PackedArray = PackedIntArray(u3, 8);
var packed_array = PackedArray.init([_]u3{ 0, 1, 2, 3, 4, 5, 6, 7 });
var i = @as(usize, 0);
while (i < packed_array.len()) : (i += 1) try testing.expectEqual(@intCast(u3, i), packed_array.get(i));
while (i < packed_array.len) : (i += 1) try testing.expectEqual(@intCast(u3, i), packed_array.get(i));
}
test "PackedIntArray initAllTo" {
if (we_are_testing_this_with_stage1_which_leaks_comptime_memory) return error.SkipZigTest;
const PackedArray = PackedIntArray(u3, 8);
var packed_array = PackedArray.initAllTo(5);
var i = @as(usize, 0);
while (i < packed_array.len()) : (i += 1) try testing.expectEqual(@as(u3, 5), packed_array.get(i));
while (i < packed_array.len) : (i += 1) try testing.expectEqual(@as(u3, 5), packed_array.get(i));
}
test "PackedIntSlice" {
@ -423,7 +427,7 @@ test "PackedIntSlice" {
//write values, counting up
var i = @as(usize, 0);
var count = @as(I, 0);
while (i < data.len()) : (i += 1) {
while (i < data.len) : (i += 1) {
data.set(i, count);
if (bits > 0) count +%= 1;
}
@ -431,7 +435,7 @@ test "PackedIntSlice" {
//read and verify values
i = 0;
count = 0;
while (i < data.len()) : (i += 1) {
while (i < data.len) : (i += 1) {
const val = data.get(i);
try testing.expect(val == count);
if (bits > 0) count +%= 1;
@ -454,14 +458,14 @@ test "PackedIntSlice of PackedInt(Array/Slice)" {
const limit = (1 << bits);
var i = @as(usize, 0);
while (i < packed_array.len()) : (i += 1) {
while (i < packed_array.len) : (i += 1) {
packed_array.set(i, @intCast(Int, i % limit));
}
//slice of array
var packed_slice = packed_array.slice(2, 5);
try testing.expect(packed_slice.len() == 3);
const ps_bit_count = (bits * packed_slice.len()) + packed_slice.bit_offset;
try testing.expect(packed_slice.len == 3);
const ps_bit_count = (bits * packed_slice.len) + packed_slice.bit_offset;
const ps_expected_bytes = (ps_bit_count + 7) / 8;
try testing.expect(packed_slice.bytes.len == ps_expected_bytes);
try testing.expect(packed_slice.get(0) == 2 % limit);
@ -475,8 +479,8 @@ test "PackedIntSlice of PackedInt(Array/Slice)" {
//slice of a slice
const packed_slice_two = packed_slice.slice(0, 3);
try testing.expect(packed_slice_two.len() == 3);
const ps2_bit_count = (bits * packed_slice_two.len()) + packed_slice_two.bit_offset;
try testing.expect(packed_slice_two.len == 3);
const ps2_bit_count = (bits * packed_slice_two.len) + packed_slice_two.bit_offset;
const ps2_expected_bytes = (ps2_bit_count + 7) / 8;
try testing.expect(packed_slice_two.bytes.len == ps2_expected_bytes);
try testing.expect(packed_slice_two.get(1) == 7 % limit);
@ -484,21 +488,21 @@ test "PackedIntSlice of PackedInt(Array/Slice)" {
//size one case
const packed_slice_three = packed_slice_two.slice(1, 2);
try testing.expect(packed_slice_three.len() == 1);
const ps3_bit_count = (bits * packed_slice_three.len()) + packed_slice_three.bit_offset;
try testing.expect(packed_slice_three.len == 1);
const ps3_bit_count = (bits * packed_slice_three.len) + packed_slice_three.bit_offset;
const ps3_expected_bytes = (ps3_bit_count + 7) / 8;
try testing.expect(packed_slice_three.bytes.len == ps3_expected_bytes);
try testing.expect(packed_slice_three.get(0) == 7 % limit);
//empty slice case
const packed_slice_empty = packed_slice.slice(0, 0);
try testing.expect(packed_slice_empty.len() == 0);
try testing.expect(packed_slice_empty.len == 0);
try testing.expect(packed_slice_empty.bytes.len == 0);
//slicing at byte boundaries
const packed_slice_edge = packed_array.slice(8, 16);
try testing.expect(packed_slice_edge.len() == 8);
const pse_bit_count = (bits * packed_slice_edge.len()) + packed_slice_edge.bit_offset;
try testing.expect(packed_slice_edge.len == 8);
const pse_bit_count = (bits * packed_slice_edge.len) + packed_slice_edge.bit_offset;
const pse_expected_bytes = (pse_bit_count + 7) / 8;
try testing.expect(packed_slice_edge.bytes.len == pse_expected_bytes);
try testing.expect(packed_slice_edge.bit_offset == 0);
@ -506,45 +510,40 @@ test "PackedIntSlice of PackedInt(Array/Slice)" {
}
test "PackedIntSlice accumulating bit offsets" {
if (we_are_testing_this_with_stage1_which_leaks_comptime_memory) return error.SkipZigTest;
//bit_offset is u3, so standard debugging asserts should catch
// anything
{
const PackedArray = PackedIntArray(u3, 16);
var packed_array = @as(PackedArray, undefined);
var packed_slice = packed_array.slice(0, packed_array.len());
var packed_slice = packed_array.slice(0, packed_array.len);
var i = @as(usize, 0);
while (i < packed_array.len() - 1) : (i += 1) {
packed_slice = packed_slice.slice(1, packed_slice.len());
while (i < packed_array.len - 1) : (i += 1) {
packed_slice = packed_slice.slice(1, packed_slice.len);
}
}
{
const PackedArray = PackedIntArray(u11, 88);
var packed_array = @as(PackedArray, undefined);
var packed_slice = packed_array.slice(0, packed_array.len());
var packed_slice = packed_array.slice(0, packed_array.len);
var i = @as(usize, 0);
while (i < packed_array.len() - 1) : (i += 1) {
packed_slice = packed_slice.slice(1, packed_slice.len());
while (i < packed_array.len - 1) : (i += 1) {
packed_slice = packed_slice.slice(1, packed_slice.len);
}
}
}
//@NOTE: As I do not have a big endian system to test this on,
// big endian values were not tested
test "PackedInt(Array/Slice) sliceCast" {
if (we_are_testing_this_with_stage1_which_leaks_comptime_memory) return error.SkipZigTest;
const PackedArray = PackedIntArray(u1, 16);
var packed_array = PackedArray.init([_]u1{ 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1 });
const packed_slice_cast_2 = packed_array.sliceCast(u2);
const packed_slice_cast_4 = packed_slice_cast_2.sliceCast(u4);
var packed_slice_cast_9 = packed_array.slice(0, (packed_array.len() / 9) * 9).sliceCast(u9);
var packed_slice_cast_9 = packed_array.slice(0, (packed_array.len / 9) * 9).sliceCast(u9);
const packed_slice_cast_3 = packed_slice_cast_9.sliceCast(u3);
var i = @as(usize, 0);
while (i < packed_slice_cast_2.len()) : (i += 1) {
while (i < packed_slice_cast_2.len) : (i += 1) {
const val = switch (native_endian) {
.Big => 0b01,
.Little => 0b10,
@ -552,7 +551,7 @@ test "PackedInt(Array/Slice) sliceCast" {
try testing.expect(packed_slice_cast_2.get(i) == val);
}
i = 0;
while (i < packed_slice_cast_4.len()) : (i += 1) {
while (i < packed_slice_cast_4.len) : (i += 1) {
const val = switch (native_endian) {
.Big => 0b0101,
.Little => 0b1010,
@ -560,13 +559,13 @@ test "PackedInt(Array/Slice) sliceCast" {
try testing.expect(packed_slice_cast_4.get(i) == val);
}
i = 0;
while (i < packed_slice_cast_9.len()) : (i += 1) {
while (i < packed_slice_cast_9.len) : (i += 1) {
const val = 0b010101010;
try testing.expect(packed_slice_cast_9.get(i) == val);
packed_slice_cast_9.set(i, 0b111000111);
}
i = 0;
while (i < packed_slice_cast_3.len()) : (i += 1) {
while (i < packed_slice_cast_3.len) : (i += 1) {
const val = switch (native_endian) {
.Big => if (i % 2 == 0) @as(u3, 0b111) else @as(u3, 0b000),
.Little => if (i % 2 == 0) @as(u3, 0b111) else @as(u3, 0b000),
@ -576,8 +575,6 @@ test "PackedInt(Array/Slice) sliceCast" {
}
test "PackedInt(Array/Slice)Endian" {
if (we_are_testing_this_with_stage1_which_leaks_comptime_memory) return error.SkipZigTest;
{
const PackedArrayBe = PackedIntArrayEndian(u4, .Big, 8);
var packed_array_be = PackedArrayBe.init([_]u4{ 0, 1, 2, 3, 4, 5, 6, 7 });
@ -585,20 +582,20 @@ test "PackedInt(Array/Slice)Endian" {
try testing.expect(packed_array_be.bytes[1] == 0b00100011);
var i = @as(usize, 0);
while (i < packed_array_be.len()) : (i += 1) {
while (i < packed_array_be.len) : (i += 1) {
try testing.expect(packed_array_be.get(i) == i);
}
var packed_slice_le = packed_array_be.sliceCastEndian(u4, .Little);
i = 0;
while (i < packed_slice_le.len()) : (i += 1) {
while (i < packed_slice_le.len) : (i += 1) {
const val = if (i % 2 == 0) i + 1 else i - 1;
try testing.expect(packed_slice_le.get(i) == val);
}
var packed_slice_le_shift = packed_array_be.slice(1, 5).sliceCastEndian(u4, .Little);
i = 0;
while (i < packed_slice_le_shift.len()) : (i += 1) {
while (i < packed_slice_le_shift.len) : (i += 1) {
const val = if (i % 2 == 0) i else i + 2;
try testing.expect(packed_slice_le_shift.get(i) == val);
}
@ -614,7 +611,7 @@ test "PackedInt(Array/Slice)Endian" {
try testing.expect(packed_array_be.bytes[4] == 0b00000000);
var i = @as(usize, 0);
while (i < packed_array_be.len()) : (i += 1) {
while (i < packed_array_be.len) : (i += 1) {
try testing.expect(packed_array_be.get(i) == i);
}
@ -639,14 +636,12 @@ test "PackedInt(Array/Slice)Endian" {
//@NOTE: Need to manually update this list as more posix os's get
// added to DirectAllocator.
//These tests prove we aren't accidentally accessing memory past
// These tests prove we aren't accidentally accessing memory past
// the end of the array/slice by placing it at the end of a page
// and reading the last element. The assumption is that the page
// after this one is not mapped and will cause a segfault if we
// don't account for the bounds.
test "PackedIntArray at end of available memory" {
if (we_are_testing_this_with_stage1_which_leaks_comptime_memory) return error.SkipZigTest;
switch (builtin.target.os.tag) {
.linux, .macos, .ios, .freebsd, .netbsd, .openbsd, .windows => {},
else => return,
@ -666,8 +661,6 @@ test "PackedIntArray at end of available memory" {
}
test "PackedIntSlice at end of available memory" {
if (we_are_testing_this_with_stage1_which_leaks_comptime_memory) return error.SkipZigTest;
switch (builtin.target.os.tag) {
.linux, .macos, .ios, .freebsd, .netbsd, .openbsd, .windows => {},
else => return,