Changed MAt.read to take an allocator
This commit is contained in:
adrien
parent
915c5cea65
commit
2c52c202fe
@ -1,3 +1,4 @@
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/// Dummy
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const std = @import("std");
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const c = @import("c.zig").c;
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const GpuAllocator = @import("GpuAllocator.zig");
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@ -62,8 +63,8 @@ pub fn add(self: Mat, gloc: *GpuAllocator, other: Mat) !Mat {
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return result;
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}
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pub fn read(self: Mat, gloc: *GpuAllocator, out: []f32) !void {
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std.debug.assert(out.len >= self.len());
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pub fn read(self: Mat, gloc: *GpuAllocator, alloc: std.mem.Allocator) ![]f32 {
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const out = try alloc.alloc(f32, self.len());
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const bytes = self.byteSize();
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const staging = try GpuBuffer.init(
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@ -94,6 +95,8 @@ pub fn read(self: Mat, gloc: *GpuAllocator, out: []f32) !void {
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));
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@memcpy(out[0..self.len()], ptr[0..self.len()]);
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staging.unmap();
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return out;
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}
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fn onMapped(
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@ -53,13 +53,8 @@ pub fn main(init: std.process.Init) !void {
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const sum = try a.add(&gloc, b);
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defer sum.deinit();
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// Read back (allocating dynamically for read-back buffers too)
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const out_sum = try allocator.alloc(f32, size);
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defer allocator.free(out_sum);
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const out_scaled = try allocator.alloc(f32, size);
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defer allocator.free(out_scaled);
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try sum.read(&gloc, out_sum);
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const out = try sum.read(&gloc, allocator);
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defer allocator.free(out);
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const duration = start.durationTo(std.Io.Clock.awake.now(init.io));
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const ns = duration.toNanoseconds();
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@ -1,238 +0,0 @@
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// Minimal WebGPU compute in Zig: element-wise matrix addition
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// Uses wgpu-native C bindings.
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// Build: see ../build.zig
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//
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// Data flow:
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// CPU (mat_a, mat_b) → GPU storage buffers → compute shader → GPU buf_c
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// → staging buffer (mapped) → CPU read → print
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const std = @import("std");
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const c = @cImport(@cInclude("wgpu.h"));
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// ── Config ────────────────────────────────────────────────────────────────────
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const ROWS: u32 = 4;
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const COLS: u32 = 4;
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const N = ROWS * COLS; // 16 elements
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const BUF_BYTES = N * @sizeOf(f32);
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// ── WGSL Compute Shader ───────────────────────────────────────────────────────
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// workgroup_size(4,4) matches one full 4×4 matrix → dispatch(1,1,1)
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const SHADER =
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\\@group(0) @binding(0) var<storage, read> mat_a : array<f32>;
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\\@group(0) @binding(1) var<storage, read> mat_b : array<f32>;
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\\@group(0) @binding(2) var<storage, read_write> mat_c : array<f32>;
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\\
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\\@compute @workgroup_size(4, 4)
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\\fn main(@builtin(global_invocation_id) gid : vec3<u32>) {
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\\ let idx = gid.y * 4u + gid.x;
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\\ if (idx < arrayLength(&mat_c)) {
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\\ mat_c[idx] = mat_a[idx] + mat_b[idx];
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\\ }
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\\}
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;
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// ── Callback state ────────────────────────────────────────────────────────────
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const Ctx = struct {
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adapter: c.WGPUAdapter = null,
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device: c.WGPUDevice = null,
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};
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fn onAdapter(
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status: c.WGPURequestAdapterStatus,
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adapter: c.WGPUAdapter,
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_: c.WGPUStringView,
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userdata1: ?*anyopaque,
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_: ?*anyopaque,
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) callconv(.c) void {
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if (status != c.WGPURequestAdapterStatus_Success) {
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std.log.err("Adapter request failed (status={d})", .{status});
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return;
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}
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const ctx: *Ctx = @ptrCast(@alignCast(userdata1.?));
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ctx.adapter = adapter;
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}
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fn onDevice(
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status: c.WGPURequestDeviceStatus,
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device: c.WGPUDevice,
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_: c.WGPUStringView,
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userdata1: ?*anyopaque,
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_: ?*anyopaque,
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) callconv(.c) void {
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if (status != c.WGPURequestDeviceStatus_Success) {
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std.log.err("Device request failed (status={d})", .{status});
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return;
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}
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const ctx: *Ctx = @ptrCast(@alignCast(userdata1.?));
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ctx.device = device;
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}
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fn onMapped(
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status: c.WGPUMapAsyncStatus,
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_: c.WGPUStringView,
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userdata1: ?*anyopaque,
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_: ?*anyopaque,
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) callconv(.c) void {
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const flag: *bool = @ptrCast(@alignCast(userdata1.?));
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flag.* = (status == c.WGPUMapAsyncStatus_Success);
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}
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fn sv(s: []const u8) c.WGPUStringView {
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return .{ .data = s.ptr, .length = s.len };
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}
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// ── Main ──────────────────────────────────────────────────────────────────────
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pub fn main() !void {
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// 1. Instance ──────────────────────────────────────────────────────────────
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const instance = c.wgpuCreateInstance(&std.mem.zeroes(c.WGPUInstanceDescriptor)) orelse
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return error.NoInstance;
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defer c.wgpuInstanceRelease(instance);
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// 2. Adapter (async → poll) ────────────────────────────────────────────────
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var ctx = Ctx{};
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_ = c.wgpuInstanceRequestAdapter(
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instance,
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&.{ .powerPreference = c.WGPUPowerPreference_HighPerformance },
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.{ .callback = onAdapter, .userdata1 = &ctx },
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);
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c.wgpuInstanceProcessEvents(instance); // drive callbacks
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const adapter = ctx.adapter orelse return error.NoAdapter;
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defer c.wgpuAdapterRelease(adapter);
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// 3. Device ────────────────────────────────────────────────────────────────
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_ = c.wgpuAdapterRequestDevice(adapter, null, .{ .callback = onDevice, .userdata1 = &ctx });
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c.wgpuInstanceProcessEvents(instance);
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const device = ctx.device orelse return error.NoDevice;
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defer c.wgpuDeviceRelease(device);
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const queue = c.wgpuDeviceGetQueue(device);
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defer c.wgpuQueueRelease(queue);
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// 4. Input data ────────────────────────────────────────────────────────────
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// mat_a[i] = i (0 … 15)
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// mat_b[i] = 15 − i → every element of mat_c should equal 15
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var mat_a: [N]f32 = undefined;
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var mat_b: [N]f32 = undefined;
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for (0..N) |i| {
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mat_a[i] = @floatFromInt(i);
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mat_b[i] = @floatFromInt(N - 1 - i);
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}
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// 5. GPU Buffers ───────────────────────────────────────────────────────────
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const buf_a = c.wgpuDeviceCreateBuffer(device, &.{
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.usage = c.WGPUBufferUsage_Storage | c.WGPUBufferUsage_CopyDst,
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.size = BUF_BYTES,
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}) orelse return error.BufferA;
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const buf_b = c.wgpuDeviceCreateBuffer(device, &.{
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.usage = c.WGPUBufferUsage_Storage | c.WGPUBufferUsage_CopyDst,
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.size = BUF_BYTES,
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}) orelse return error.BufferB;
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// buf_c: GPU-only result; staging: CPU-readable copy
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const buf_c = c.wgpuDeviceCreateBuffer(device, &.{
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.usage = c.WGPUBufferUsage_Storage | c.WGPUBufferUsage_CopySrc,
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.size = BUF_BYTES,
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}) orelse return error.BufferC;
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const buf_staging = c.wgpuDeviceCreateBuffer(device, &.{
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.usage = c.WGPUBufferUsage_MapRead | c.WGPUBufferUsage_CopyDst,
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.size = BUF_BYTES,
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}) orelse return error.BufferStaging;
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defer c.wgpuBufferRelease(buf_a);
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defer c.wgpuBufferRelease(buf_b);
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defer c.wgpuBufferRelease(buf_c);
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defer c.wgpuBufferRelease(buf_staging);
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// Upload inputs
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c.wgpuQueueWriteBuffer(queue, buf_a, 0, &mat_a, BUF_BYTES);
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c.wgpuQueueWriteBuffer(queue, buf_b, 0, &mat_b, BUF_BYTES);
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// 6. Shader module ─────────────────────────────────────────────────────────
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// ✅ New API (0.20+)
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var wgsl_src = c.WGPUShaderSourceWGSL{
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.chain = .{ .sType = c.WGPUSType_ShaderSourceWGSL },
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.code = sv(SHADER),
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};
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const shader = c.wgpuDeviceCreateShaderModule(device, &.{
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.nextInChain = @ptrCast(&wgsl_src),
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}) orelse return error.Shader;
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// 7. Compute pipeline (layout auto-inferred from shader) ───────────────────
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// ✅
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const pipeline = c.wgpuDeviceCreateComputePipeline(device, &.{
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.compute = .{
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.module = shader,
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.entryPoint = sv("main"),
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},
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}) orelse return error.Pipeline;
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defer c.wgpuComputePipelineRelease(pipeline);
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// 8. Bind group ────────────────────────────────────────────────────────────
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const bgl = c.wgpuComputePipelineGetBindGroupLayout(pipeline, 0);
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defer c.wgpuBindGroupLayoutRelease(bgl);
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const entries = [_]c.WGPUBindGroupEntry{
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.{ .binding = 0, .buffer = buf_a, .offset = 0, .size = BUF_BYTES },
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.{ .binding = 1, .buffer = buf_b, .offset = 0, .size = BUF_BYTES },
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.{ .binding = 2, .buffer = buf_c, .offset = 0, .size = BUF_BYTES },
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};
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const bind_group = c.wgpuDeviceCreateBindGroup(device, &.{
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.layout = bgl,
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.entries = &entries,
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.entryCount = entries.len,
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}) orelse return error.BindGroup;
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defer c.wgpuBindGroupRelease(bind_group);
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// 9. Encode compute pass + buffer copy ────────────────────────────────────
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const encoder = c.wgpuDeviceCreateCommandEncoder(device, null) orelse
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return error.Encoder;
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const pass = c.wgpuCommandEncoderBeginComputePass(encoder, null);
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c.wgpuComputePassEncoderSetPipeline(pass, pipeline);
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c.wgpuComputePassEncoderSetBindGroup(pass, 0, bind_group, 0, null);
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// dispatch(1,1,1): one workgroup of size (4,4) covers the whole 4×4 matrix
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c.wgpuComputePassEncoderDispatchWorkgroups(pass, 1, 1, 1);
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c.wgpuComputePassEncoderEnd(pass);
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c.wgpuComputePassEncoderRelease(pass);
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// Copy result buffer → CPU-readable staging buffer
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c.wgpuCommandEncoderCopyBufferToBuffer(encoder, buf_c, 0, buf_staging, 0, BUF_BYTES);
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const cmdbuf = c.wgpuCommandEncoderFinish(encoder, null);
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defer c.wgpuCommandEncoderRelease(encoder);
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defer c.wgpuCommandBufferRelease(cmdbuf);
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// 10. Submit ───────────────────────────────────────────────────────────────
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c.wgpuQueueSubmit(queue, 1, &cmdbuf);
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// 11. Map staging buffer back to CPU ──────────────────────────────────────
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var mapped = false;
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_ = c.wgpuBufferMapAsync(
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buf_staging,
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c.WGPUMapMode_Read,
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0,
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BUF_BYTES,
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.{ .callback = onMapped, .userdata1 = &mapped },
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);
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// Poll the device until the async map completes
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while (!mapped) _ = c.wgpuDevicePoll(device, 1, null);
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const ptr: [*]const f32 = @ptrCast(@alignCast(
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c.wgpuBufferGetConstMappedRange(buf_staging, 0, BUF_BYTES),
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));
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const result = ptr[0..N];
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// 12. Print ────────────────────────────────────────────────────────────────
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std.debug.print("\nmat_a + mat_b ({d}×{d}):\n", .{ ROWS, COLS });
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for (0..ROWS) |r| {
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for (0..COLS) |col|
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std.debug.print("{d:6.0}", .{result[r * COLS + col]});
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std.debug.print("\n", .{});
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}
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// Expected output: every cell = 15.0
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c.wgpuBufferUnmap(buf_staging);
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}
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@ -1,18 +1,3 @@
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const std = @import("std");
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pub const SHADER_ADD = @embedFile("shaders/add.wgsl");
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pub const SHADER_SCALE =
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\\struct Uniforms { scalar : f32 }
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\\@group(0) @binding(0) var<storage, read> a : array<f32>;
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\\@group(0) @binding(1) var<storage, read_write> out : array<f32>;
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\\@group(0) @binding(2) var<uniform> u : Uniforms;
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\\
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\\@compute @workgroup_size(256)
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\\fn main(@builtin(global_invocation_id) gid : vec3<u32>) {
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\\ let i = gid.x;
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\\ if (i < arrayLength(&out)) {
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\\ out[i] = a[i] * u.scalar;
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\\ }
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\\}
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;
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