Add more png benchmarks for alternative mimic libs
On a mid-range x86_64 laptop:
"libpng" (Debian's /usr/lib/x86_64-linux-gnu/libpng16.so) numbers are
used as a 1.00x baseline for the other libraries.
(†): libpng's "simplified API" doesn't provide a way to ignore the
checksum. We copy the "verify_checksum" numbers for a 1.00x baseline.
Some of the other libraries don't have the option to ignore or verify
the checksum, always doing only one or the other.
----
libpng_decode_19k_8bpp 58.0MB/s ± 0% 1.00x
libpng_decode_40k_24bpp 73.1MB/s ± 0% 1.00x
libpng_decode_77k_8bpp 177MB/s ± 0% 1.00x
libpng_decode_552k_32bpp_ignore_checksum 146MB/s ± 0% (†)
libpng_decode_552k_32bpp_verify_checksum 146MB/s ± 0% 1.00x
libpng_decode_4002k_24bpp 104MB/s ± 0% 1.00x
----
wuffs_decode_19k_8bpp/clang9 131MB/s ± 0% 2.26x
wuffs_decode_40k_24bpp/clang9 153MB/s ± 0% 2.09x
wuffs_decode_77k_8bpp/clang9 472MB/s ± 0% 2.67x
wuffs_decode_552k_32bpp_ignore_checksum/clang9 370MB/s ± 0% 2.53x
wuffs_decode_552k_32bpp_verify_checksum/clang9 357MB/s ± 0% 2.45x
wuffs_decode_4002k_24bpp/clang9 156MB/s ± 0% 1.50x
wuffs_decode_19k_8bpp/gcc10 136MB/s ± 1% 2.34x
wuffs_decode_40k_24bpp/gcc10 162MB/s ± 0% 2.22x
wuffs_decode_77k_8bpp/gcc10 486MB/s ± 0% 2.75x
wuffs_decode_552k_32bpp_ignore_checksum/gcc10 388MB/s ± 0% 2.66x
wuffs_decode_552k_32bpp_verify_checksum/gcc10 373MB/s ± 0% 2.55x
wuffs_decode_4002k_24bpp/gcc10 164MB/s ± 0% 1.58x
----
libspng_decode_19k_8bpp/clang9 59.3MB/s ± 0% 1.02x
libspng_decode_40k_24bpp/clang9 78.4MB/s ± 0% 1.07x
libspng_decode_77k_8bpp/clang9 189MB/s ± 0% 1.07x
libspng_decode_552k_32bpp_ignore_checksum/clang9 236MB/s ± 0% 1.62x
libspng_decode_552k_32bpp_verify_checksum/clang9 203MB/s ± 0% 1.39x
libspng_decode_4002k_24bpp/clang9 110MB/s ± 0% 1.06x
libspng_decode_19k_8bpp/gcc10 59.6MB/s ± 0% 1.03x
libspng_decode_40k_24bpp/gcc10 77.5MB/s ± 0% 1.06x
libspng_decode_77k_8bpp/gcc10 189MB/s ± 0% 1.07x
libspng_decode_552k_32bpp_ignore_checksum/gcc10 223MB/s ± 0% 1.53x
libspng_decode_552k_32bpp_verify_checksum/gcc10 194MB/s ± 0% 1.33x
libspng_decode_4002k_24bpp/gcc10 109MB/s ± 0% 1.05x
----
lodepng_decode_19k_8bpp/clang9 65.1MB/s ± 0% 1.12x
lodepng_decode_40k_24bpp/clang9 72.1MB/s ± 0% 0.99x
lodepng_decode_77k_8bpp/clang9 222MB/s ± 0% 1.25x
lodepng_decode_552k_32bpp_ignore_checksum/clang9 skipped
lodepng_decode_552k_32bpp_verify_checksum/clang9 162MB/s ± 0% 1.11x
lodepng_decode_4002k_24bpp/clang9 70.5MB/s ± 0% 0.68x
lodepng_decode_19k_8bpp/gcc10 61.1MB/s ± 0% 1.05x
lodepng_decode_40k_24bpp/gcc10 62.5MB/s ± 1% 0.85x
lodepng_decode_77k_8bpp/gcc10 176MB/s ± 0% 0.99x
lodepng_decode_552k_32bpp_ignore_checksum/gcc10 skipped
lodepng_decode_552k_32bpp_verify_checksum/gcc10 139MB/s ± 0% 0.95x
lodepng_decode_4002k_24bpp/gcc10 62.3MB/s ± 0% 0.60x
----
stbimage_decode_19k_8bpp/clang9 75.1MB/s ± 1% 1.29x
stbimage_decode_40k_24bpp/clang9 84.6MB/s ± 0% 1.16x
stbimage_decode_77k_8bpp/clang9 234MB/s ± 0% 1.32x
stbimage_decode_552k_32bpp_ignore_checksum/clang9 162MB/s ± 0% 1.11x
stbimage_decode_552k_32bpp_verify_checksum/clang9 skipped
stbimage_decode_4002k_24bpp/clang9 80.7MB/s ± 0% 0.78x
stbimage_decode_19k_8bpp/gcc10 73.3MB/s ± 0% 1.26x
stbimage_decode_40k_24bpp/gcc10 81.8MB/s ± 0% 1.12x
stbimage_decode_77k_8bpp/gcc10 214MB/s ± 0% 1.21x
stbimage_decode_552k_32bpp_ignore_checksum/gcc10 145MB/s ± 0% 0.99x
stbimage_decode_552k_32bpp_verify_checksum/gcc10 skipped
stbimage_decode_4002k_24bpp/gcc10 79.7MB/s ± 0% 0.77x
----
go_decode_19k_8bpp/go1.16 39.3MB/s ± 1% 0.68x
go_decode_40k_24bpp/go1.16 46.5MB/s ± 1% 0.64x
go_decode_77k_8bpp/go1.16 78.3MB/s ± 0% 0.44x
go_decode_552k_32bpp_ignore_checksum/go1.16 skipped
go_decode_552k_32bpp_verify_checksum/go1.16 120MB/s ± 1% 0.82x
go_decode_4002k_24bpp/go1.16 50.7MB/s ± 0% 0.49x
----
rust_decode_19k_8bpp/rust1.48 88.3MB/s ± 0% 1.52x
rust_decode_40k_24bpp/rust1.48 133MB/s ± 0% 1.82x
rust_decode_77k_8bpp/rust1.48 180MB/s ± 0% 1.02x
rust_decode_552k_32bpp_ignore_checksum/rust1.48 skipped
rust_decode_552k_32bpp_verify_checksum/rust1.48 146MB/s ± 0% 1.00x
rust_decode_4002k_24bpp/rust1.48 134MB/s ± 0% 1.29x
diff --git a/script/bench-go-png/main.go b/script/bench-go-png/main.go
new file mode 100644
index 0000000..5c5c036
--- /dev/null
+++ b/script/bench-go-png/main.go
@@ -0,0 +1,157 @@
+// Copyright 2021 The Wuffs Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build ignore
+
+package main
+
+// This program exercises the Go standard library's PNG decoder.
+//
+// Wuffs' C code doesn't depend on Go per se, but this program gives some
+// performance data for specific Go PNG implementations. The equivalent Wuffs
+// benchmarks (on the same test images) are run via:
+//
+// wuffs bench std/png
+
+import (
+ "bytes"
+ "fmt"
+ "image"
+ "image/draw"
+ "image/png"
+ "io/ioutil"
+ "os"
+ "runtime"
+ "strings"
+ "time"
+)
+
+const (
+ iterscale = 20
+ reps = 5
+)
+
+type testCase = struct {
+ benchname string
+ src []byte
+ itersUnscaled uint32
+}
+
+var testCases = []testCase{{
+ benchname: "go_png_decode_image_19k_8bpp",
+ src: mustLoad("test/data/bricks-gray.no-ancillary.png"),
+ itersUnscaled: 50,
+}, {
+ benchname: "go_png_decode_image_40k_24bpp",
+ src: mustLoad("test/data/hat.png"),
+ itersUnscaled: 50,
+}, {
+ benchname: "go_png_decode_image_77k_8bpp",
+ src: mustLoad("test/data/bricks-dither.png"),
+ itersUnscaled: 50,
+}, {
+ benchname: "go_png_decode_image_552k_32bpp_verify_checksum",
+ src: mustLoad("test/data/hibiscus.primitive.png"),
+ itersUnscaled: 4,
+}, {
+ benchname: "go_png_decode_image_4002k_24bpp",
+ src: mustLoad("test/data/harvesters.png"),
+ itersUnscaled: 1,
+}}
+
+func mustLoad(filename string) []byte {
+ src, err := ioutil.ReadFile("../../" + filename)
+ if err != nil {
+ panic(err.Error())
+ }
+ return src
+}
+
+func main() {
+ if err := main1(); err != nil {
+ os.Stderr.WriteString(err.Error() + "\n")
+ os.Exit(1)
+ }
+}
+
+func main1() error {
+ fmt.Printf("# Go %s\n", runtime.Version())
+ fmt.Printf("#\n")
+ fmt.Printf("# The output format, including the \"Benchmark\" prefixes, is compatible with the\n")
+ fmt.Printf("# https://godoc.org/golang.org/x/perf/cmd/benchstat tool. To install it, first\n")
+ fmt.Printf("# install Go, then run \"go get golang.org/x/perf/cmd/benchstat\".\n")
+
+ for i := -1; i < reps; i++ {
+ for _, tc := range testCases {
+ runtime.GC()
+
+ start := time.Now()
+
+ iters := uint64(tc.itersUnscaled) * iterscale
+ bgra := strings.HasSuffix(tc.benchname, "_77k_8bpp")
+ numBytes, err := decode(tc.src, bgra)
+ if err != nil {
+ return err
+ }
+ for j := uint64(1); j < iters; j++ {
+ decode(tc.src, bgra)
+ }
+
+ elapsedNanos := time.Since(start)
+
+ kbPerS := numBytes * uint64(iters) * 1000000 / uint64(elapsedNanos)
+
+ if i < 0 {
+ continue // Warm up rep.
+ }
+
+ fmt.Printf("Benchmark%-30s %8d %12d ns/op %8d.%03d MB/s\n",
+ tc.benchname, iters, uint64(elapsedNanos)/iters, kbPerS/1000, kbPerS%1000)
+ }
+ }
+
+ return nil
+}
+
+func decode(src []byte, bgra bool) (numBytes uint64, retErr error) {
+ m, err := png.Decode(bytes.NewReader(src))
+ if err != nil {
+ return 0, err
+ }
+
+ b := m.Bounds()
+ n := uint64(b.Dx()) * uint64(b.Dy())
+
+ // Go converts to RGBA (as that's what Go's image/draw standard library is
+ // optimized for); Wuffs converts to BGRA. The difference isn't important,
+ // as we just want measure how long it takes.
+ if bgra {
+ dst := image.NewRGBA(b)
+ draw.Draw(dst, b, m, b.Min, draw.Src)
+ m = dst
+ }
+
+ switch m.(type) {
+ case *image.Gray:
+ n *= 1
+ case *image.NRGBA:
+ n *= 4
+ case *image.RGBA:
+ n *= 4
+ default:
+ return 0, fmt.Errorf("unexpected image type %T", m)
+ }
+
+ return n, nil
+}
diff --git a/script/bench-rust-png/Cargo.toml b/script/bench-rust-png/Cargo.toml
new file mode 100644
index 0000000..3664f3e
--- /dev/null
+++ b/script/bench-rust-png/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "bench_rust_png"
+version = "0.0.1"
+authors = ["Nigel Tao <nigeltao@golang.org>"]
+
+[dependencies]
+png = "*"
+rustc_version_runtime = "*"
diff --git a/script/bench-rust-png/src/main.rs b/script/bench-rust-png/src/main.rs
new file mode 100644
index 0000000..5bd7348
--- /dev/null
+++ b/script/bench-rust-png/src/main.rs
@@ -0,0 +1,152 @@
+// Copyright 2021 The Wuffs Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// ----------------
+
+// This program exercises the Rust PNG decoder at
+// https://github.com/image-rs/image-png
+// which is the top result for https://crates.io/search?q=png&sort=downloads
+//
+// Wuffs' C code doesn't depend on Rust per se, but this program gives some
+// performance data for specific Rust PNG implementations. The equivalent Wuffs
+// benchmarks (on the same test images) are run via:
+//
+// wuffs bench std/png
+//
+// To run this program, do "cargo run --release" from the parent directory (the
+// directory containing the Cargo.toml file).
+
+extern crate png;
+extern crate rustc_version_runtime;
+
+use std::time::Instant;
+
+const ITERSCALE: u64 = 50;
+const REPS: u64 = 5;
+
+fn main() {
+ let version = rustc_version_runtime::version();
+ print!(
+ "# Rust {}.{}.{}\n",
+ version.major, version.minor, version.patch,
+ );
+ print!("#\n");
+ print!("# The output format, including the \"Benchmark\" prefixes, is compatible with the\n");
+ print!("# https://godoc.org/golang.org/x/perf/cmd/benchstat tool. To install it, first\n");
+ print!("# install Go, then run \"go get golang.org/x/perf/cmd/benchstat\".\n");
+
+ let mut dst = vec![0u8; 64 * 1024 * 1024];
+
+ // The various magic constants below are copied from test/c/std/png.c
+ for i in 0..(1 + REPS) {
+ bench(
+ "19k_8bpp",
+ &mut dst[..],
+ include_bytes!("../../../test/data/bricks-gray.no-ancillary.png"),
+ i == 0, // warm_up
+ 160 * 120 * 1, // want_num_bytes = 19_200
+ 50, // iters_unscaled
+ );
+
+ bench(
+ "40k_24bpp",
+ &mut dst[..],
+ include_bytes!("../../../test/data/hat.png"),
+ i == 0, // warm_up
+ 90 * 112 * 4, // want_num_bytes = 40_320
+ 30, // iters_unscaled
+ );
+
+ bench(
+ "77k_8bpp",
+ &mut dst[..],
+ include_bytes!("../../../test/data/bricks-dither.png"),
+ i == 0, // warm_up
+ 160 * 120 * 4, // want_num_bytes = 76_800
+ 30, // iters_unscaled
+ );
+
+ bench(
+ "552k_32bpp_verify_checksum",
+ &mut dst[..],
+ include_bytes!("../../../test/data/hibiscus.primitive.png"),
+ i == 0, // warm_up
+ 312 * 442 * 4, // want_num_bytes = 551_616
+ 4, // iters_unscaled
+ );
+
+ bench(
+ "4002k_24bpp",
+ &mut dst[..],
+ include_bytes!("../../../test/data/harvesters.png"),
+ i == 0, // warm_up
+ 1165 * 859 * 4, // want_num_bytes = 4_002_940
+ 1, // iters_unscaled
+ );
+ }
+}
+
+fn bench(
+ name: &str, // Benchmark name.
+ dst: &mut [u8], // Destination buffer.
+ src: &[u8], // Source data.
+ warm_up: bool, // Whether this is a warm up rep.
+ want_num_bytes: u64, // Expected num_bytes per iteration.
+ iters_unscaled: u64, // Base number of iterations.
+) {
+ let iters = iters_unscaled * ITERSCALE;
+ let mut total_num_bytes = 0u64;
+
+ let start = Instant::now();
+ for _ in 0..iters {
+ let n = decode(&mut dst[..], src);
+ if n != want_num_bytes {
+ panic!("num_bytes: got {}, want {}", n, want_num_bytes);
+ }
+ total_num_bytes += n;
+ }
+ let elapsed = start.elapsed();
+
+ let elapsed_nanos = (elapsed.as_secs() * 1_000_000_000) + (elapsed.subsec_nanos() as u64);
+ let kb_per_s: u64 = total_num_bytes * 1_000_000 / elapsed_nanos;
+
+ if warm_up {
+ return;
+ }
+
+ print!(
+ "Benchmarkrust_png_decode_image_{:16} {:8} {:12} ns/op {:3}.{:03} MB/s\n",
+ name,
+ iters,
+ elapsed_nanos / iters,
+ kb_per_s / 1_000,
+ kb_per_s % 1_000
+ );
+}
+
+// decode returns the number of bytes processed.
+fn decode(dst: &mut [u8], src: &[u8]) -> u64 {
+ let decoder = png::Decoder::new(src);
+ let (info, mut reader) = decoder.read_info().unwrap();
+ let num_bytes = info.buffer_size() as u64;
+ reader.next_frame(dst).unwrap();
+ if info.color_type == png::ColorType::RGB {
+ // If the PNG image is RGB (not RGBA) then Rust's png crate will decode
+ // to 3 bytes per pixel. Wuffs' std/png benchmarks decode to 4 bytes
+ // per pixel (and in BGRA order, not RGB or RGBA). We'll hand-wave the
+ // difference away and say that we decoded 33% more pixels than we did.
+ return (num_bytes / 3) * 4;
+ }
+ num_bytes
+}
diff --git a/test/c/mimiclib/png.c b/test/c/mimiclib/png.c
index 32acd63..2b3396b 100644
--- a/test/c/mimiclib/png.c
+++ b/test/c/mimiclib/png.c
@@ -14,10 +14,18 @@
// ----------------
-// Uncomment this line to test and bench libspng instead of libpng.
+// Uncomment one of these #define lines to test and bench alternative mimic
+// libraries (libspng, lodepng or stb_image) instead of libpng.
+//
+// These are collectively referred to as
+// WUFFS_MIMICLIB_USE_XXX_INSTEAD_OF_LIBPNG.
+//
// #define WUFFS_MIMICLIB_USE_LIBSPNG_INSTEAD_OF_LIBPNG 1
+// #define WUFFS_MIMICLIB_USE_LODEPNG_INSTEAD_OF_LIBPNG 1
+// #define WUFFS_MIMICLIB_USE_STB_IMAGE_INSTEAD_OF_LIBPNG 1
-#ifdef WUFFS_MIMICLIB_USE_LIBSPNG_INSTEAD_OF_LIBPNG
+// -------------------------------- WUFFS_MIMICLIB_USE_XXX_INSTEAD_OF_LIBPNG
+#if defined(WUFFS_MIMICLIB_USE_LIBSPNG_INSTEAD_OF_LIBPNG)
// We #include a foo.c file, not a foo.h file, as libspng is a "single file C
// library".
@@ -26,6 +34,9 @@
// We deliberately do not define the
// WUFFS_MIMICLIB_PNG_DOES_NOT_SUPPORT_QUIRK_IGNORE_CHECKSUM macro.
+// We deliberately do not define the
+// WUFFS_MIMICLIB_PNG_DOES_NOT_VERIFY_CHECKSUM macro.
+
// libspng (version 0.6.2, released November 2020) calculates but does not
// verify the CRC-32 checksum on the final IDAT chunk. It also does not verify
// the Adler-32 checksum. After calling spng_decode_image, it ends in
@@ -68,6 +79,7 @@
}
int fmt = 0;
+ bool swap_bgra_rgba = false;
switch (pixfmt.repr) {
case WUFFS_BASE__PIXEL_FORMAT__Y:
fmt = SPNG_FMT_G8;
@@ -76,6 +88,7 @@
// libspng doesn't do BGRA8. RGBA8 is the closest approximation. We'll
// fix it up later.
fmt = SPNG_FMT_RGBA8;
+ swap_bgra_rgba = true;
break;
default:
ret = "mimic_png_decode: unsupported pixfmt";
@@ -103,7 +116,7 @@
}
// Fix up BGRA8 vs RGBA8.
- if (fmt == SPNG_FMT_RGBA8) {
+ if (swap_bgra_rgba) {
for (; n >= 4; n -= 4) {
uint8_t swap = dst_ptr[0];
dst_ptr[0] = dst_ptr[2];
@@ -117,12 +130,206 @@
return ret;
}
-#else // WUFFS_MIMICLIB_USE_LIBSPNG_INSTEAD_OF_LIBPNG
+// -------------------------------- WUFFS_MIMICLIB_USE_XXX_INSTEAD_OF_LIBPNG
+#elif defined(WUFFS_MIMICLIB_USE_LODEPNG_INSTEAD_OF_LIBPNG)
+
+// We #include a foo.cpp file, not a foo.h file, as lodepng is a "single file
+// C++ library".
+#include "/path/to/your/copy/of/github.com/lvandeve/lodepng/lodepng.cpp"
+
+#define WUFFS_MIMICLIB_PNG_DOES_NOT_SUPPORT_QUIRK_IGNORE_CHECKSUM 1
+
+// We deliberately do not define the
+// WUFFS_MIMICLIB_PNG_DOES_NOT_VERIFY_CHECKSUM macro.
+
+// We deliberately do not define the
+// WUFFS_MIMICLIB_PNG_DOES_NOT_VERIFY_FINAL_IDAT_CHECKSUMS macro.
+
+const char* //
+mimic_png_decode(uint64_t* n_bytes_out,
+ wuffs_base__io_buffer* dst,
+ uint32_t wuffs_initialize_flags,
+ wuffs_base__pixel_format pixfmt,
+ uint32_t* quirks_ptr,
+ size_t quirks_len,
+ wuffs_base__io_buffer* src) {
+ wuffs_base__io_buffer dst_fallback =
+ wuffs_base__slice_u8__writer(g_mimiclib_scratch_slice_u8);
+ if (!dst) {
+ dst = &dst_fallback;
+ }
+
+ uint64_t n = 0;
+ LodePNGColorType color_type = 0;
+ unsigned int bitdepth = 8;
+ bool swap_bgra_rgba = false;
+ switch (pixfmt.repr) {
+ case WUFFS_BASE__PIXEL_FORMAT__Y:
+ n = 1;
+ color_type = LCT_GREY;
+ break;
+ case WUFFS_BASE__PIXEL_FORMAT__BGRA_NONPREMUL:
+ n = 4;
+ // lodepng doesn't do BGRA8. RGBA8 is the closest approximation. We'll
+ // fix it up later.
+ color_type = LCT_RGBA;
+ swap_bgra_rgba = true;
+ break;
+ default:
+ return "mimic_png_decode: unsupported pixfmt";
+ }
+
+ unsigned char* output = 0;
+ unsigned int width = 0;
+ unsigned int height = 0;
+ unsigned int err =
+ lodepng_decode_memory(&output, &width, &height, //
+ wuffs_base__io_buffer__reader_pointer(src), //
+ wuffs_base__io_buffer__reader_length(src), //
+ color_type, bitdepth);
+ if (err) {
+ return lodepng_error_text(err);
+ }
+
+ const char* ret = NULL;
+
+ if ((width > 0xFFFF) || (height > 0xFFFF)) {
+ ret = "mimic_png_decode: image is too large";
+ goto cleanup0;
+ }
+ n *= ((uint64_t)width) * ((uint64_t)height);
+ if (n > wuffs_base__io_buffer__writer_length(dst)) {
+ ret = "mimic_png_decode: image is too large";
+ goto cleanup0;
+ }
+
+ // Copy from the mimic library's output buffer to Wuffs' dst buffer.
+ uint8_t* dst_ptr = wuffs_base__io_buffer__writer_pointer(dst);
+ memcpy(dst_ptr, output, n);
+ dst->meta.wi += n;
+ if (n_bytes_out) {
+ *n_bytes_out += n;
+ }
+
+ // Fix up BGRA8 vs RGBA8.
+ if (swap_bgra_rgba) {
+ for (; n >= 4; n -= 4) {
+ uint8_t swap = dst_ptr[0];
+ dst_ptr[0] = dst_ptr[2];
+ dst_ptr[2] = swap;
+ dst_ptr += 4;
+ }
+ }
+
+cleanup0:;
+ free(output);
+ return ret;
+}
+
+// -------------------------------- WUFFS_MIMICLIB_USE_XXX_INSTEAD_OF_LIBPNG
+#elif defined(WUFFS_MIMICLIB_USE_STB_IMAGE_INSTEAD_OF_LIBPNG)
+
+// We #include a foo.cpp file, not a foo.h file, as stb_image is a "single file
+// C library".
+#define STB_IMAGE_IMPLEMENTATION
+#include "/path/to/your/copy/of/github.com/nothings/stb/stb_image.h"
+
+// We deliberately do not define the
+// WUFFS_MIMICLIB_PNG_DOES_NOT_SUPPORT_QUIRK_IGNORE_CHECKSUM macro. The
+// stb_image library always ignores checksums.
+
+#define WUFFS_MIMICLIB_PNG_DOES_NOT_VERIFY_CHECKSUM 1
+
+// We deliberately do not define the
+// WUFFS_MIMICLIB_PNG_DOES_NOT_VERIFY_FINAL_IDAT_CHECKSUMS macro.
+
+const char* //
+mimic_png_decode(uint64_t* n_bytes_out,
+ wuffs_base__io_buffer* dst,
+ uint32_t wuffs_initialize_flags,
+ wuffs_base__pixel_format pixfmt,
+ uint32_t* quirks_ptr,
+ size_t quirks_len,
+ wuffs_base__io_buffer* src) {
+ wuffs_base__io_buffer dst_fallback =
+ wuffs_base__slice_u8__writer(g_mimiclib_scratch_slice_u8);
+ if (!dst) {
+ dst = &dst_fallback;
+ }
+
+ uint64_t n = 0;
+ bool swap_bgra_rgba = false;
+ switch (pixfmt.repr) {
+ case WUFFS_BASE__PIXEL_FORMAT__Y:
+ n = 1;
+ break;
+ case WUFFS_BASE__PIXEL_FORMAT__BGRA_NONPREMUL:
+ n = 4;
+ // stb_image doesn't do BGRA8. RGBA8 is the closest approximation. We'll
+ // fix it up later.
+ swap_bgra_rgba = true;
+ break;
+ default:
+ return "mimic_png_decode: unsupported pixfmt";
+ }
+
+ int width = 0;
+ int height = 0;
+ int channels_in_file = 0;
+ unsigned char* output =
+ stbi_load_from_memory(wuffs_base__io_buffer__reader_pointer(src), //
+ wuffs_base__io_buffer__reader_length(src), //
+ &width, &height, &channels_in_file, n);
+ if (!output) {
+ return "mimic_png_decode: could not load image";
+ }
+
+ const char* ret = NULL;
+
+ if ((width > 0xFFFF) || (height > 0xFFFF)) {
+ ret = "mimic_png_decode: image is too large";
+ goto cleanup0;
+ }
+ n *= ((uint64_t)width) * ((uint64_t)height);
+ if (n > wuffs_base__io_buffer__writer_length(dst)) {
+ ret = "mimic_png_decode: image is too large";
+ goto cleanup0;
+ }
+
+ // Copy from the mimic library's output buffer to Wuffs' dst buffer.
+ uint8_t* dst_ptr = wuffs_base__io_buffer__writer_pointer(dst);
+ memcpy(dst_ptr, output, n);
+ dst->meta.wi += n;
+ if (n_bytes_out) {
+ *n_bytes_out += n;
+ }
+
+ // Fix up BGRA8 vs RGBA8.
+ if (swap_bgra_rgba) {
+ for (; n >= 4; n -= 4) {
+ uint8_t swap = dst_ptr[0];
+ dst_ptr[0] = dst_ptr[2];
+ dst_ptr[2] = swap;
+ dst_ptr += 4;
+ }
+ }
+
+cleanup0:;
+ stbi_image_free(output);
+ return ret;
+}
+
+// -------------------------------- WUFFS_MIMICLIB_USE_XXX_INSTEAD_OF_LIBPNG
+#else
+
#include "png.h"
#define WUFFS_MIMICLIB_PNG_DOES_NOT_SUPPORT_QUIRK_IGNORE_CHECKSUM 1
// We deliberately do not define the
+// WUFFS_MIMICLIB_PNG_DOES_NOT_VERIFY_CHECKSUM macro.
+
+// We deliberately do not define the
// WUFFS_MIMICLIB_PNG_DOES_NOT_VERIFY_FINAL_IDAT_CHECKSUMS macro.
const char* //
@@ -201,4 +408,6 @@
png_image_free(&pi);
return ret;
}
-#endif // WUFFS_MIMICLIB_USE_LIBSPNG_INSTEAD_OF_LIBPNG
+
+#endif
+// -------------------------------- WUFFS_MIMICLIB_USE_XXX_INSTEAD_OF_LIBPNG
diff --git a/test/c/std/png.c b/test/c/std/png.c
index 6adda6d..b4e94a9 100644
--- a/test/c/std/png.c
+++ b/test/c/std/png.c
@@ -815,7 +815,9 @@
#ifdef WUFFS_MIMIC
test_mimic_png_decode_bad_crc32_checksum_ancillary,
+#ifndef WUFFS_MIMICLIB_PNG_DOES_NOT_VERIFY_CHECKSUM
test_mimic_png_decode_bad_crc32_checksum_critical,
+#endif
test_mimic_png_decode_image_19k_8bpp,
test_mimic_png_decode_image_40k_24bpp,
test_mimic_png_decode_image_77k_8bpp,
@@ -852,7 +854,9 @@
#ifndef WUFFS_MIMICLIB_PNG_DOES_NOT_SUPPORT_QUIRK_IGNORE_CHECKSUM
bench_mimic_png_decode_image_552k_32bpp_ignore_checksum,
#endif
+#ifndef WUFFS_MIMICLIB_PNG_DOES_NOT_VERIFY_CHECKSUM
bench_mimic_png_decode_image_552k_32bpp_verify_checksum,
+#endif
bench_mimic_png_decode_image_4002k_24bpp,
#endif // WUFFS_MIMIC
