76 lines
2.6 KiB
Zig
76 lines
2.6 KiB
Zig
//! A Zig allocator from VkAllocationCallbacks.
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//! Falls back on c_allocator if callbacks passed are null
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const std = @import("std");
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const vk = @import("vulkan");
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const builtin = @import("builtin");
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const DRIVER_DEBUG_ALLOCATOR_ENV_NAME = @import("lib.zig").DRIVER_DEBUG_ALLOCATOR_ENV_NAME;
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const Allocator = std.mem.Allocator;
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const Alignment = std.mem.Alignment;
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const Self = @This();
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pub var debug_allocator: std.heap.DebugAllocator(.{}) = .init;
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callbacks: ?vk.AllocationCallbacks,
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scope: vk.SystemAllocationScope,
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pub fn init(callbacks: ?*const vk.AllocationCallbacks, scope: vk.SystemAllocationScope) Self {
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const deref_callbacks = if (callbacks) |c| c.* else null;
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return .{
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.callbacks = deref_callbacks,
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.scope = scope,
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};
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}
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pub fn allocator(self: *const Self) Allocator {
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if (self.callbacks != null) {
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return .{
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.ptr = @constCast(self),
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.vtable = &.{
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.alloc = alloc,
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.resize = resize,
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.remap = remap,
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.free = free,
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},
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};
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}
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return if (std.process.hasEnvVarConstant(DRIVER_DEBUG_ALLOCATOR_ENV_NAME) or builtin.mode == std.builtin.OptimizeMode.Debug)
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debug_allocator.allocator()
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else
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std.heap.c_allocator;
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}
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fn alloc(context: *anyopaque, len: usize, alignment: Alignment, _: usize) ?[*]u8 {
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const self: *Self = @ptrCast(@alignCast(context));
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if (self.callbacks.?.pfn_allocation) |pfn_allocation| {
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return @ptrCast(pfn_allocation(self.callbacks.?.p_user_data, len, alignment.toByteUnits(), self.scope));
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}
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@panic("Null PFN_vkAllocationFunction passed to VkAllocationCallbacks");
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}
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fn resize(context: *anyopaque, ptr: []u8, alignment: Alignment, new_len: usize, _: usize) bool {
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_ = alignment;
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_ = context;
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return new_len <= ptr.len;
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}
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fn remap(context: *anyopaque, ptr: []u8, alignment: Alignment, new_len: usize, _: usize) ?[*]u8 {
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const self: *Self = @ptrCast(@alignCast(context));
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if (self.callbacks.?.pfn_reallocation) |pfn_reallocation| {
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return @ptrCast(pfn_reallocation(self.callbacks.?.p_user_data, ptr.ptr, new_len, alignment.toByteUnits(), self.scope));
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}
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@panic("Null PFN_vkReallocationFunction passed to VkAllocationCallbacks");
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}
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fn free(context: *anyopaque, ptr: []u8, alignment: Alignment, _: usize) void {
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_ = alignment;
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const self: *Self = @ptrCast(@alignCast(context));
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if (self.callbacks.?.pfn_free) |pfn_free| {
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return pfn_free(self.callbacks.?.p_user_data, ptr.ptr);
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}
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@panic("Null PFN_vkFreeFunction passed to VkAllocationCallbacks");
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}
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