go-libwebp

commit 61bcd809df050051345098e0c46884ccc52c8c97
parent 55f31ea7f7298c3aeb2a7b051784a7ff313f0d35
Author: Jack Mordaunt <jackmordaunt.dev@gmail.com>
Date:   Wed,  3 Jan 2024 16:30:32 +0800

lib/transpiled: add decode and fix asm panic

Signed-off-by: Jack Mordaunt <jackmordaunt.dev@gmail.com>

Diffstat:
M
lib/transpiled/webp/lib.go
 | 
80
+++++++++++++++++++++++++++++++++++++++++++------------------------------------

1 file changed, 44 insertions(+), 36 deletions(-)
diff --git a/lib/transpiled/webp/lib.go b/lib/transpiled/webp/lib.go
@@ -1,51 +1,59 @@
 package webp
 
 import (
-	"unsafe"
+	"image"
+	"io"
 
+	"git.sr.ht/~jackmordaunt/go-libwebp/lib/common"
 	"modernc.org/libc"
 )
 
-var tls *libc.TLS
-
-func EncodeImpl(
-	in unsafe.Pointer,
-	w int32,
-	h int32,
-	bps int32,
-	q float32,
-	out unsafe.Pointer,
-) (size uint64) {
-	tls = libc.NewTLS()
+func DecodeImpl(buf []byte) (image.Image, error) {
+	disableVP8GetCPUInfo()
+	tls := libc.NewTLS()
 	defer tls.Close()
+	return common.Decode(buf, makeDecodeImpl(tls), makeFreeImpl(tls))
+}
+
+func EncodeImpl(w io.Writer, m *image.RGBA, quality float32) error {
+	tls := libc.NewTLS()
+	defer tls.Close()
+	return common.Encode(w, m, quality, makeEncodeImpl(tls), makeFreeImpl(tls))
+}
 
-	if q >= 1.0 {
-		size = WebPEncodeLosslessRGBA(
-			tls,
-			uintptr(in),
-			w,
-			h,
-			bps,
-			uintptr(out),
-		)
-	} else {
-		size = WebPEncodeRGBA(
-			tls,
-			uintptr(in),
-			w,
-			h,
-			bps,
-			q,
-			uintptr(out),
-		)
+func makeDecodeImpl(tls *libc.TLS) common.DecoderFunc {
+	return func(data uintptr, data_size uint64, width, height uintptr) uintptr {
+		return WebPDecodeRGBA(tls, data, data_size, width, height)
 	}
+}
 
-	return size
+func makeEncodeImpl(tls *libc.TLS) common.EncodeFunc {
+	return func(in uintptr, w, h, bps int32, q float32, out uintptr) uint64 {
+		if q >= 1.0 {
+			return WebPEncodeLosslessRGBA(tls, in, w, h, bps, out)
+		}
+		return WebPEncodeRGBA(tls, in, w, h, bps, q, out)
+	}
 }
 
-func FreeImpl(ptr unsafe.Pointer) {
-	if tls == nil {
-		panic("tls is nil, invalid use of transpile api")
+func makeFreeImpl(tls *libc.TLS) common.FreeFunc {
+	return func(p uintptr) {
+		WebPFree(tls, p)
 	}
-	WebPFree(tls, uintptr(ptr))
+}
+
+func disableVP8GetCPUInfo() {
+	// HACK: Avoid panic when decoding lossy webp data.
+	//
+	// Inline asm is used for CPU feature detection; ccgo doesn't support inline asm.
+	//
+	// libwebp uses this function pointer to check for any specialized CPU instructions.
+	// If not nil (which it is for well supported platforms, like amd64, and arm64), it will try
+	// to check CPU features using inline asm. ccgo inserts a panic for inline asm, thus using
+	// this will panic.
+	//
+	// To avoid this terrible fate, we must manually turn off the CPU feature detection by
+	// nil'ing out this function pointer. This must be done after package init since that is
+	// is when this value is set by the transpiled code.
+	VP8GetCPUInfo = 0
 }