Allow aligning the raw image buffer

Added code to allocate aligned image buffer in vpx_img_alloc(). The
alignment of the buffer and stride is determined by the parameter
align.

Change-Id: Idc866978484be3558551c56df39130ab7f74ddd4

diff --git a/vpx/src/vpx_image.c b/vpx/src/vpx_image.c
index 7a4e270..336b6e2 100644 (file)
--- a/vpx/src/vpx_image.c
+++ b/vpx/src/vpx_image.c
@@ -13,10 +13,42 @@
 #include <string.h>
 #include "vpx/vpx_image.h"
 
+#define ADDRESS_STORAGE_SIZE      sizeof(size_t)
+/*returns an addr aligned to the byte boundary specified by align*/
+#define align_addr(addr,align) (void*)(((size_t)(addr) + ((align) - 1)) & (size_t)-(align))
+
+/* Memalign code is copied from vpx_mem.c */
+static void *img_buf_memalign(size_t align, size_t size)
+{
+    void *addr,
+         * x = NULL;
+
+    addr = malloc(size + align - 1 + ADDRESS_STORAGE_SIZE);
+
+    if (addr)
+    {
+        x = align_addr((unsigned char *)addr + ADDRESS_STORAGE_SIZE, (int)align);
+        /* save the actual malloc address */
+        ((size_t *)x)[-1] = (size_t)addr;
+    }
+
+    return x;
+}
+
+static void img_buf_free(void *memblk)
+{
+    if (memblk)
+    {
+        void *addr = (void *)(((size_t *)memblk)[-1]);
+        free(addr);
+    }
+}
+
 static vpx_image_t *img_alloc_helper(vpx_image_t  *img,
                                      vpx_img_fmt_t fmt,
                                      unsigned int  d_w,
                                      unsigned int  d_h,
+                                     unsigned int  buf_align,
                                      unsigned int  stride_align,
                                      unsigned char      *img_data)
 {
@@ -25,6 +57,14 @@ static vpx_image_t *img_alloc_helper(vpx_image_t  *img,
     int           align;
 
     /* Treat align==0 like align==1 */
+    if (!buf_align)
+        buf_align = 1;
+
+    /* Validate alignment (must be power of 2) */
+    if (buf_align & (buf_align - 1))
+        goto fail;
+
+    /* Treat align==0 like align==1 */
     if (!stride_align)
         stride_align = 1;
 
@@ -119,7 +159,8 @@ static vpx_image_t *img_alloc_helper(vpx_image_t  *img,
 
     if (!img_data)
     {
-        img->img_data = malloc((fmt & VPX_IMG_FMT_PLANAR) ? h * w * bps / 8 : h * s);
+        img->img_data = img_buf_memalign(buf_align, ((fmt & VPX_IMG_FMT_PLANAR)?
+                                         h * s * bps / 8 : h * s));
         img->img_data_owner = 1;
     }
 
@@ -150,9 +191,9 @@ vpx_image_t *vpx_img_alloc(vpx_image_t  *img,
                            vpx_img_fmt_t fmt,
                            unsigned int  d_w,
                            unsigned int  d_h,
-                           unsigned int  stride_align)
+                           unsigned int  align)
 {
-    return img_alloc_helper(img, fmt, d_w, d_h, stride_align, NULL);
+    return img_alloc_helper(img, fmt, d_w, d_h, align, align, NULL);
 }
 
 vpx_image_t *vpx_img_wrap(vpx_image_t  *img,
@@ -162,7 +203,9 @@ vpx_image_t *vpx_img_wrap(vpx_image_t  *img,
                           unsigned int  stride_align,
                           unsigned char       *img_data)
 {
-    return img_alloc_helper(img, fmt, d_w, d_h, stride_align, img_data);
+    /* By setting buf_align = 1, we don't change buffer alignment in this
+     * function. */
+    return img_alloc_helper(img, fmt, d_w, d_h, 1, stride_align, img_data);
 }
 
 int vpx_img_set_rect(vpx_image_t  *img,
@@ -254,7 +297,7 @@ void vpx_img_free(vpx_image_t *img)
     if (img)
     {
         if (img->img_data && img->img_data_owner)
-            free(img->img_data);
+            img_buf_free(img->img_data);
 
         if (img->self_allocd)
             free(img);

diff --git a/vpx/vpx_image.h b/vpx/vpx_image.h
index 8e08b36..3e42447 100644 (file)
--- a/vpx/vpx_image.h
+++ b/vpx/vpx_image.h
@@ -160,7 +160,8 @@ extern "C" {
      * \param[in]    fmt       Format for the image
      * \param[in]    d_w       Width of the image
      * \param[in]    d_h       Height of the image
-     * \param[in]    align     Alignment, in bytes, of each row in the image.
+     * \param[in]    align     Alignment, in bytes, of the image buffer and
+     *                         each row in the image(stride).
      *
      * \return Returns a pointer to the initialized image descriptor. If the img
      *         parameter is non-null, the value of the img parameter will be