X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavutil%2Ffifo.c;h=5774d33d256b2b1944f4c09a2b23ad3e05f6a01a;hb=7658295ba353b8bedb3af904f46cfb1ba0cea86a;hp=19715ebce46ef007337d1e8eb6abba44d40297e1;hpb=8257b835cf4d422ca3f0426ac2e151f5dff69ecb;p=ffmpeg

diff --git a/libavutil/fifo.c b/libavutil/fifo.c
index 19715ebce46..5774d33d256 100644
--- a/libavutil/fifo.c
+++ b/libavutil/fifo.c
@@ -1,85 +1,84 @@
 /*
- * A very simple circular buffer FIFO implementation
+ * a very simple circular buffer FIFO implementation
  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
  * Copyright (c) 2006 Roman Shaposhnik
  *
- * This file is part of FFmpeg.
+ * This file is part of Libav.
  *
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
- * FFmpeg is distributed in the hope that it will be useful,
+ * Libav is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
+ * License along with Libav; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 #include "common.h"
 #include "fifo.h"
 
-int av_fifo_init(AVFifoBuffer *f, unsigned int size)
+AVFifoBuffer *av_fifo_alloc(unsigned int size)
 {
-    size= FFMAX(size, size+1);
-    f->wptr = f->rptr =
+    AVFifoBuffer *f= av_mallocz(sizeof(AVFifoBuffer));
+    if(!f)
+        return NULL;
     f->buffer = av_malloc(size);
     f->end = f->buffer + size;
+    av_fifo_reset(f);
     if (!f->buffer)
-        return -1;
-    return 0;
+        av_freep(&f);
+    return f;
 }
 
 void av_fifo_free(AVFifoBuffer *f)
 {
-    av_free(f->buffer);
+    if(f){
+        av_free(f->buffer);
+        av_free(f);
+    }
 }
 
-int av_fifo_size(AVFifoBuffer *f)
+void av_fifo_reset(AVFifoBuffer *f)
 {
-    int size = f->wptr - f->rptr;
-    if (size < 0)
-        size += f->end - f->buffer;
-    return size;
+    f->wptr = f->rptr = f->buffer;
+    f->wndx = f->rndx = 0;
 }
 
-int av_fifo_read(AVFifoBuffer *f, uint8_t *buf, int buf_size)
+int av_fifo_size(AVFifoBuffer *f)
 {
-    return av_fifo_generic_read(f, buf_size, NULL, buf);
+    return (uint32_t)(f->wndx - f->rndx);
 }
 
-/**
- * Resizes a FIFO.
- */
-void av_fifo_realloc(AVFifoBuffer *f, unsigned int new_size) {
-    av_fifo_realloc2(f, new_size);
+int av_fifo_space(AVFifoBuffer *f)
+{
+    return f->end - f->buffer - av_fifo_size(f);
 }
 
 int av_fifo_realloc2(AVFifoBuffer *f, unsigned int new_size) {
     unsigned int old_size= f->end - f->buffer;
 
-    if(old_size <= new_size){
+    if(old_size < new_size){
         int len= av_fifo_size(f);
-        AVFifoBuffer f2;
+        AVFifoBuffer *f2= av_fifo_alloc(new_size);
 
-        if (av_fifo_init(&f2, new_size) < 0)
+        if (!f2)
             return -1;
-        av_fifo_read(f, f2.buffer, len);
-        f2.wptr += len;
+        av_fifo_generic_read(f, f2->buffer, len, NULL);
+        f2->wptr += len;
+        f2->wndx += len;
         av_free(f->buffer);
-        *f= f2;
+        *f= *f2;
+        av_free(f2);
     }
     return 0;
 }
 
-void av_fifo_write(AVFifoBuffer *f, const uint8_t *buf, int size)
-{
-    av_fifo_generic_write(f, (void *)buf, size, NULL);
-}
-
+// src must NOT be const as it can be a context for func that may need updating (like a pointer or byte counter)
 int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int))
 {
     int total = size;
@@ -92,17 +91,20 @@ int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void
             memcpy(f->wptr, src, len);
             src = (uint8_t*)src + len;
         }
+// Write memory barrier needed for SMP here in theory
         f->wptr += len;
         if (f->wptr >= f->end)
             f->wptr = f->buffer;
+        f->wndx += len;
         size -= len;
     } while (size > 0);
     return total - size;
 }
 
 
-int av_fifo_generic_read(AVFifoBuffer *f, int buf_size, void (*func)(void*, void*, int), void* dest)
+int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int))
 {
+// Read memory barrier needed for SMP here in theory
     do {
         int len = FFMIN(f->end - f->rptr, buf_size);
         if(func) func(dest, f->rptr, len);
@@ -110,16 +112,54 @@ int av_fifo_generic_read(AVFifoBuffer *f, int buf_size, void (*func)(void*, void
             memcpy(dest, f->rptr, len);
             dest = (uint8_t*)dest + len;
         }
+// memory barrier needed for SMP here in theory
         av_fifo_drain(f, len);
         buf_size -= len;
     } while (buf_size > 0);
     return 0;
 }
 
-/** discard data from the fifo */
+/** Discard data from the FIFO. */
 void av_fifo_drain(AVFifoBuffer *f, int size)
 {
     f->rptr += size;
     if (f->rptr >= f->end)
         f->rptr -= f->end - f->buffer;
+    f->rndx += size;
+}
+
+#ifdef TEST
+
+#undef printf
+
+int main(void)
+{
+    /* create a FIFO buffer */
+    AVFifoBuffer *fifo = av_fifo_alloc(13 * sizeof(int));
+    int i, j, n;
+
+    /* fill data */
+    for (i = 0; av_fifo_space(fifo) >= sizeof(int); i++)
+        av_fifo_generic_write(fifo, &i, sizeof(int), NULL);
+
+    /* peek at FIFO */
+    n = av_fifo_size(fifo)/sizeof(int);
+    for (i = -n+1; i < n; i++) {
+        int *v = (int *)av_fifo_peek2(fifo, i*sizeof(int));
+        printf("%d: %d\n", i, *v);
+    }
+    printf("\n");
+
+    /* read data */
+    for (i = 0; av_fifo_size(fifo) >= sizeof(int); i++) {
+        av_fifo_generic_read(fifo, &j, sizeof(int), NULL);
+        printf("%d ", j);
+    }
+    printf("\n");
+
+    av_fifo_free(fifo);
+
+    return 0;
 }
+
+#endif