stream_filter: implement prefetch module for OS/2

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/stream_filter/prefetch.c

@@ -33,7 +33,7 @@
 #ifndef MAP_ANONYMOUS
 # define MAP_ANONYMOUS MAP_ANON
 #endif
-#else
+#elif !defined(__OS2__)
 #include <errno.h>
 #define MAP_FAILED ((void *)-1)
 #define mmap(a,l,p,f,d,o) \
@@ -476,7 +476,7 @@ static int Open(vlc_object_t *obj)
     if (sys->buffer_size < sys->read_size)
         sys->buffer_size = sys->read_size;
 
-#ifndef _WIN32
+#if !defined(_WIN32) && !defined(__OS2__)
     /* Round up to a multiple of the page size */
     long page_size = sysconf(_SC_PAGESIZE);
 
@@ -502,6 +502,110 @@ static int Open(vlc_object_t *obj)
         goto error;
     }
     close(fd);
+#elif defined(__OS2__)
+    /* On OS/2 Warp, page size is 4K, but the smallest chunk size is 64K */
+    int page_size = 64 * 1024;
+
+    sys->buffer_size += page_size - 1;
+    sys->buffer_size &= ~(page_size - 1);
+    sys->buffer = NULL;
+
+    char *buffer;
+
+    if (DosAllocMem(&buffer, 2 * sys->buffer_size, fALLOC))
+        goto error;
+
+    struct buffer_list
+    {
+        char *buffer;
+        struct buffer_list *next;
+    } *buffer_list_start = NULL;
+
+    for (;;)
+    {
+        char *buf;
+        if (DosAllocMem(&buf, sys->buffer_size, fPERM | OBJ_TILE))
+            break;
+
+        struct buffer_list *new_buffer = calloc(1, sizeof(*new_buffer));
+
+        if (!new_buffer)
+        {
+            DosFreeMem(buf);
+            break;
+        }
+
+        new_buffer->buffer = buf;
+        new_buffer->next = buffer_list_start;
+
+        buffer_list_start = new_buffer;
+
+        if (buf > buffer)
+        {
+            /* Disable thread switching */
+            DosEnterCritSec();
+
+            char *addr = buffer;
+
+            DosFreeMem(buffer);
+            buffer = NULL;
+
+            if (DosAllocMem(&buf, sys->buffer_size, fALLOC))
+                goto exitcritsec;
+
+            /* Was hole ? */
+            if (buf < addr)
+            {
+                DosFreeMem(buf);
+                buf = NULL;
+
+                char *tmp;
+
+                /* Try to fill the hole out */
+                if (DosAllocMem(&tmp, addr - buf, fALLOC))
+                    goto exitcritsec;
+
+                DosAllocMem(&buf, sys->buffer_size, fALLOC);
+
+                DosFreeMem(tmp);
+            }
+
+            if (buf != addr)
+            {
+                DosFreeMem(buf);
+                goto exitcritsec;
+            }
+
+            char *alias = NULL;
+
+            if (!DosAliasMem(buf, sys->buffer_size, &alias, 0)
+             && alias == buf + sys->buffer_size)
+                sys->buffer = addr;
+            else
+            {
+                DosFreeMem(buf);
+                DosFreeMem(alias);
+            }
+
+exitcritsec:
+            /* Enable thread switching */
+            DosExitCritSec();
+            break;
+        }
+    }
+
+    DosFreeMem(buffer);
+
+    for (struct buffer_list *l = buffer_list_start, *next; l; l = next)
+    {
+        next = l->next;
+
+        DosFreeMem(l->buffer);
+        free(l);
+    }
+
+    if (sys->buffer == NULL)
+        goto error;
 #else
     SYSTEM_INFO info;
     GetSystemInfo(&info);
@@ -574,9 +678,15 @@ static int Open(vlc_object_t *obj)
     return VLC_SUCCESS;
 
 error:
-#ifndef _WIN32
+#if !defined(_WIN32) && !defined(__OS2__)
     if (sys->buffer != MAP_FAILED)
         munmap(sys->buffer, 2 * sys->buffer_size);
+#elif defined(__OS2__)
+    if (sys->buffer != NULL)
+    {
+        DosFreeMem(sys->buffer + sys->buffer_size);
+        DosFreeMem(sys->buffer);
+    }
 #else
     if (sys->buffer != NULL)
     {
@@ -605,8 +715,11 @@ static void Close (vlc_object_t *obj)
     vlc_cond_destroy(&sys->wait_data);
     vlc_mutex_destroy(&sys->lock);
 
-#ifndef _WIN32
+#if !defined(_WIN32) && !defined(__OS2__)
     munmap(sys->buffer, 2 * sys->buffer_size);
+#elif defined(__OS2__)
+    DosFreeMem(sys->buffer + sys->buffer_size);
+    DosFreeMem(sys->buffer);
 #else
     UnmapViewOfFile(sys->buffer + sys->buffer_size);
     UnmapViewOfFile(sys->buffer);