Add outer alloc memory buffer options.

Add outer_alloc flag
Add int quirc_set_image_buffer(struct quirc* q, uint8_t* image_buffer);
call quirc_set_image_buffer(struct quirc* q, uint8_t* image_buffer); before int quirc_resize(struct quirc *q, int w, int h);
tested on esp32s2 (esp-idf 4.2)

lib/quirc.c

@@ -36,7 +36,9 @@ struct quirc *quirc_new(void)
 
 void quirc_destroy(struct quirc *q)
 {
+	if (!q->outer_alloc)
 		free(q->image);
+
 	/* q->pixels may alias q->image when their type representation is of the
 	   same size, so we need to be careful here to avoid a double free */
 	if (!QUIRC_PIXEL_ALIAS_IMAGE)
@@ -44,9 +46,23 @@ void quirc_destroy(struct quirc *q)
 	free(q->flood_fill_vars);
 	free(q);
 }
-
-int quirc_resize(struct quirc *q, int w, int h)
-{
+int quirc_set_image_buffer(struct quirc* q, uint8_t* image_buffer) {
+	if (q->image == image_buffer) {
+		q->outer_alloc = (q->image == NULL)? 0 : 1;
+		return 0;
+	}
+	if (q->image != NULL && !q->outer_alloc) {
+		free(q->image);
+		q->image = NULL;
+		q->outer_alloc = 0;
+	}
+	if (image_buffer != NULL) {
+		q->image = image_buffer;
+		q->outer_alloc = 1;
+	}
+	return 0;
+}
+int quirc_resize(struct quirc* q, int w, int h) {
 	uint8_t* image = NULL;
 	quirc_pixel_t* pixels = NULL;
 	size_t num_vars;
@@ -66,9 +82,11 @@ int quirc_resize(struct quirc *q, int w, int h)
 	 * alloc a new buffer for q->image. We avoid realloc(3) because we want
 	 * on failure to be leave `q` in a consistant, unmodified state.
 	 */
+	if (!q->outer_alloc) {
 		image = calloc(w , h);
 		if (!image)
 			goto fail;
+	}
 
 	/* compute the "old" (i.e. currently allocated) and the "new"
 	   (i.e. requested) image dimensions */
@@ -81,6 +99,7 @@ int quirc_resize(struct quirc *q, int w, int h)
 	 * old buffer when the new size is greater and (b) to write beyond the
 	 * new buffer when the new size is smaller, hence the min computation.
 	 */
+	if (q->image)
 		(void)memcpy(image , q->image , min);
 
 	/* alloc a new buffer for q->pixels if needed */
@@ -120,8 +139,12 @@ int quirc_resize(struct quirc *q, int w, int h)
 	/* alloc succeeded, update `q` with the new size and buffers */
 	q->w = w;
 	q->h = h;
+	if(!q->outer_alloc) {
+		if (q->image != NULL)
 		free(q->image);
 		q->image = image;
+	}
+	
 	if (!QUIRC_PIXEL_ALIAS_IMAGE) {
 		free(q->pixels);
 		q->pixels = pixels;
@@ -133,6 +156,7 @@ int quirc_resize(struct quirc *q, int w, int h)
 	return 0;
 	/* NOTREACHED */
 fail:
+	if (!q->outer_alloc)
 		free(image);
 	free(pixels);
 	free(vars);

lib/quirc.h

@@ -36,6 +36,15 @@ struct quirc *quirc_new(void);
 /* Destroy a QR-code recognizer. */
 void quirc_destroy(struct quirc *q);
 
+/* Set the QR-code recognizer. use internal allocation memory or external 
+ * allocation memory buffer.
+ * specified before call quirc_resize. use internal allocation memory buffer.
+ *
+ * This function returns 0 on success, or -1 if sufficient memory could
+ * not be allocated.
+ */
+int quirc_set_image_buffer(struct quirc* q, uint8_t* image_buffer);
+
 /* Resize the QR-code recognizer. The size of an image must be
  * specified before codes can be analyzed.
  *

lib/quirc_internal.h

@@ -103,6 +103,8 @@ struct quirc {
 
 	size_t      		num_flood_fill_vars;
 	struct quirc_flood_fill_vars *flood_fill_vars;
+
+	uint8_t outer_alloc;
 };
 
 /************************************************************************