[U-Boot] [PATCH V4] lcd: align bmp header when uncopmressing image

[Piotr Wilczek]

When compressed image is loaded, it must be decompressed
to an aligned address + 2 to avoid unaligned access exception
on some ARM platforms.

Signed-off-by: Piotr Wilczek <p.wilczek at samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
CC: Anatolij Gustschin <agust at denx.de>
CC: Wolfgang Denk <wd at denx.de>
---
Changes for V4:
- dropped the if condition

Changes for V3:
- add comment on why extra space is allocated for uncompressed bmp header
- change the + 2 aligment method as Wolfgang Denk suggested

Changes for V2:
- add additional space for uncompressed bmp header due to alignment requirements
- fix to 32-bit-aligned-address + 2 alignent

 common/cmd_bmp.c |   42 ++++++++++++++++++++++++++++--------------
 include/lcd.h    |    3 ++-
 2 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/common/cmd_bmp.c b/common/cmd_bmp.c
index 5a52edd..675f47a 100644
--- a/common/cmd_bmp.c
+++ b/common/cmd_bmp.c
@@ -38,14 +38,19 @@ static int bmp_info (ulong addr);
 /*
  * Allocate and decompress a BMP image using gunzip().
  *
- * Returns a pointer to the decompressed image data. Must be freed by
- * the caller after use.
+ * Returns a pointer to the decompressed image data. This pointer is
+ * is aligned to 32-bit-aligned-address + 2.
+ * See doc/README.displaying-bmps for explanation.
+ *
+ * The allocation address is passed to 'alloc_addr' and must be freed
+ * by the caller after use.
  *
  * Returns NULL if decompression failed, or if the decompressed data
  * didn't contain a valid BMP signature.
  */
 #ifdef CONFIG_VIDEO_BMP_GZIP
-bmp_image_t *gunzip_bmp(unsigned long addr, unsigned long *lenp)
+bmp_image_t *gunzip_bmp(unsigned long addr, unsigned long *lenp,
+			void **alloc_addr)
 {
 	void *dst;
 	unsigned long len;
@@ -55,12 +60,19 @@ bmp_image_t *gunzip_bmp(unsigned long addr, unsigned long *lenp)
 	 * Decompress bmp image
 	 */
 	len = CONFIG_SYS_VIDEO_LOGO_MAX_SIZE;
-	dst = malloc(CONFIG_SYS_VIDEO_LOGO_MAX_SIZE);
+	/* allocate extra 3 bytes for 32-bit-aligned-address + 2 alignment */
+	dst = malloc(CONFIG_SYS_VIDEO_LOGO_MAX_SIZE + 3);
 	if (dst == NULL) {
 		puts("Error: malloc in gunzip failed!\n");
 		return NULL;
 	}
-	if (gunzip(dst, CONFIG_SYS_VIDEO_LOGO_MAX_SIZE, (uchar *)addr, &len) != 0) {
+
+	bmp = dst;
+
+	/* align to 32-bit-aligned-address + 2 */
+	bmp = (bmp_image_t *)((((unsigned int)dst + 1) & ~3) + 2);
+
+	if (gunzip(bmp, CONFIG_SYS_VIDEO_LOGO_MAX_SIZE, (uchar *)addr, &len) != 0) {
 		free(dst);
 		return NULL;
 	}
@@ -68,8 +80,6 @@ bmp_image_t *gunzip_bmp(unsigned long addr, unsigned long *lenp)
 		puts("Image could be truncated"
 				" (increase CONFIG_SYS_VIDEO_LOGO_MAX_SIZE)!\n");
 
-	bmp = dst;
-
 	/*
 	 * Check for bmp mark 'BM'
 	 */
@@ -81,10 +91,12 @@ bmp_image_t *gunzip_bmp(unsigned long addr, unsigned long *lenp)
 
 	debug("Gzipped BMP image detected!\n");
 
+	*alloc_addr = dst;
 	return bmp;
 }
 #else
-bmp_image_t *gunzip_bmp(unsigned long addr, unsigned long *lenp)
+bmp_image_t *gunzip_bmp(unsigned long addr, unsigned long *lenp,
+			void **alloc_addr)
 {
 	return NULL;
 }
@@ -189,11 +201,12 @@ U_BOOT_CMD(
 static int bmp_info(ulong addr)
 {
 	bmp_image_t *bmp=(bmp_image_t *)addr;
+	void *bmp_alloc_addr = NULL;
 	unsigned long len;
 
 	if (!((bmp->header.signature[0]=='B') &&
 	      (bmp->header.signature[1]=='M')))
-		bmp = gunzip_bmp(addr, &len);
+		bmp = gunzip_bmp(addr, &len, &bmp_alloc_addr);
 
 	if (bmp == NULL) {
 		printf("There is no valid bmp file at the given address\n");
@@ -205,8 +218,8 @@ static int bmp_info(ulong addr)
 	printf("Bits per pixel: %d\n", le16_to_cpu(bmp->header.bit_count));
 	printf("Compression   : %d\n", le32_to_cpu(bmp->header.compression));
 
-	if ((unsigned long)bmp != addr)
-		free(bmp);
+	if (bmp_alloc_addr)
+		free(bmp_alloc_addr);
 
 	return(0);
 }
@@ -225,11 +238,12 @@ int bmp_display(ulong addr, int x, int y)
 {
 	int ret;
 	bmp_image_t *bmp = (bmp_image_t *)addr;
+	void *bmp_alloc_addr = NULL;
 	unsigned long len;
 
 	if (!((bmp->header.signature[0]=='B') &&
 	      (bmp->header.signature[1]=='M')))
-		bmp = gunzip_bmp(addr, &len);
+		bmp = gunzip_bmp(addr, &len, &bmp_alloc_addr);
 
 	if (!bmp) {
 		printf("There is no valid bmp file at the given address\n");
@@ -244,8 +258,8 @@ int bmp_display(ulong addr, int x, int y)
 # error bmp_display() requires CONFIG_LCD or CONFIG_VIDEO
 #endif
 
-	if ((unsigned long)bmp != addr)
-		free(bmp);
+	if (bmp_alloc_addr)
+		free(bmp_alloc_addr);
 
 	return ret;
 }
diff --git a/include/lcd.h b/include/lcd.h
index c6e7fc5..482e606 100644
--- a/include/lcd.h
+++ b/include/lcd.h
@@ -46,7 +46,8 @@ void lcd_initcolregs(void);
 int lcd_getfgcolor(void);
 
 /* gunzip_bmp used if CONFIG_VIDEO_BMP_GZIP */
-struct bmp_image *gunzip_bmp(unsigned long addr, unsigned long *lenp);
+struct bmp_image *gunzip_bmp(unsigned long addr, unsigned long *lenp,
+			     void **alloc_addr);
 int bmp_display(ulong addr, int x, int y);
 
 /**
-- 
1.7.9.5