tiny.simd.AlignedAllocation

1pub fn Allocation(comptime T: type) type {2    if (@sizeOf(T) == 0) @compileError("aligned allocations require nonzero-sized values");3    if (@alignOf(T) > allocation_alignment) {4        @compileError("value alignment exceeds the Highway allocation alignment");5    }67    return struct {8        allocation: []u8,9        values: []align(allocation_alignment) T,1011        const Self = @This();1213        pub fn init(allocator: std.mem.Allocator, count: usize) Error!Self {14            if (count == 0) return error.EmptyAllocation;15            const payload_bytes = std.math.mul(usize, count, @sizeOf(T)) catch16                return error.AllocationSizeOverflow;17            if (payload_bytes >= std.math.maxInt(usize) / 2) {18                return error.AllocationSizeOverflow;19            }20            const offset = nextAlignedOffset();21            const prefix_bytes = std.math.add(usize, alias_bytes, offset) catch22                return error.AllocationSizeOverflow;23            const allocated_bytes = std.math.add(usize, prefix_bytes, payload_bytes) catch24                return error.AllocationSizeOverflow;25            const allocation = try allocator.alloc(u8, allocated_bytes);26            errdefer allocator.free(allocation);27            const aligned_base = std.mem.alignBackward(28                usize,29                @intFromPtr(allocation.ptr) + alias_bytes,30                alias_bytes,31            );32            const payload_address = aligned_base + offset;33            std.debug.assert(payload_address >= @intFromPtr(allocation.ptr));34            std.debug.assert(payload_address + payload_bytes <=35                @intFromPtr(allocation.ptr) + allocation.len);36            std.debug.assert(payload_address % allocation_alignment == 0);37            const payload_offset = payload_address - @intFromPtr(allocation.ptr);38            const byte_pointer: [*]align(allocation_alignment) u8 =39                @alignCast(allocation.ptr + payload_offset);40            const pointer: [*]align(allocation_alignment) T = @ptrCast(byte_pointer);41            return .{42                .allocation = allocation,43                .values = pointer[0..count],44            };45        }4647        pub fn deinit(self: *Self, allocator: std.mem.Allocator) void {48            allocator.free(self.allocation);49            self.* = undefined;50        }5152        pub fn slice(self: *Self) []T {53            return self.values;54        }5556        pub fn constSlice(self: *const Self) []const T {57            return self.values;58        }59    };60}

1pub const AlignedAllocation = aligned.Allocation;