[PATCH 3/4] winedmo: Use the stream context to cache stream chunks.

[Rémi Bernon]

From: Rémi Bernon

---
 dlls/winedmo/main.c    |  5 ++--
 dlls/winedmo/unixlib.c | 63 +++++++++++++++++++++++++++---------------
 dlls/winedmo/unixlib.h | 10 ++++---
 3 files changed, 50 insertions(+), 28 deletions(-)

diff --git a/dlls/winedmo/main.c b/dlls/winedmo/main.c
index 1e91d8e2e51..849c1e675cb 100644
--- a/dlls/winedmo/main.c
+++ b/dlls/winedmo/main.c
@@ -30,11 +30,12 @@ static struct stream_context *stream_context_create( struct winedmo_stream *stre
 {
     struct stream_context *context;

-    if (!(context = malloc( 0x10000 ))) return NULL;
+    if (!(context = malloc( sizeof(*context) + 0x10000 ))) return NULL;
     context->stream = (UINT_PTR)stream;
     context->length = stream_size;
     context->position = 0;
-    context->buffer_size = 0x10000 - offsetof(struct stream_context, buffer);
+    context->capacity = 0x10000;
+    context->size = 0;

return context;
 }
diff --git a/dlls/winedmo/unixlib.c b/dlls/winedmo/unixlib.c
index 15500ee10b4..c8d37ce90c5 100644
--- a/dlls/winedmo/unixlib.c
+++ b/dlls/winedmo/unixlib.c
@@ -46,42 +46,61 @@ int64_t unix_seek_callback( void *opaque, int64_t offset, int whence )
     if (whence == SEEK_END) offset += context->length;
     if (whence == SEEK_CUR) offset += context->position;

-    params.offset = offset;
-    status = KeUserDispatchCallback( &params.dispatch, sizeof(params), &ret_ptr, &ret_len );
-    if (status || ret_len != sizeof(UINT64)) return AVERROR( EINVAL );
-    offset = *(UINT64 *)ret_ptr;
+    if (offset / context->capacity != context->position / context->capacity)
+    {
+        for (;;)
+        {
+            /* seek stream to multiples of buffer capacity */
+            params.offset = (offset / context->capacity) * context->capacity;
+            status = KeUserDispatchCallback( &params.dispatch, sizeof(params), &ret_ptr, &ret_len );
+            if (status || ret_len != sizeof(UINT64)) return AVERROR( EINVAL );
+            if (*(UINT64 *)ret_ptr == params.offset) break;
+            offset = *(UINT64 *)ret_ptr;
+        }
+        context->size = 0;
+    }

context->position = offset;
     return offset;
 }

+static int stream_context_read( struct stream_context *context )
+{
+    struct read_callback_params params = {.dispatch = {.callback = read_callback}, .context = (UINT_PTR)context};
+    void *ret_ptr;
+    ULONG ret_len;
+    int status;
+
+    params.size = context->capacity;
+    status = KeUserDispatchCallback( &params.dispatch, sizeof(params), &ret_ptr, &ret_len );
+    if (status || ret_len != sizeof(ULONG)) return AVERROR( EINVAL );
+    context->size = *(ULONG *)ret_ptr;
+    return 0;
+}
+
 int unix_read_callback( void *opaque, uint8_t *buffer, int size )
 {
     struct stream_context *context = opaque;
-    int ret, status, total = 0;
-
-    TRACE( "opaque %p, buffer %p, size %#x\n", opaque, buffer, size );
+    int ret, total = 0;

if (!size) return AVERROR_EOF;

-    do
+    while (size)
     {
-        struct read_callback_params params = {.dispatch = {.callback = read_callback}, .context = (UINT_PTR)context};
-        void *ret_ptr;
-        ULONG ret_len;
-
-        params.size = min( size, context->buffer_size );
-        status = KeUserDispatchCallback( &params.dispatch, sizeof(params), &ret_ptr, &ret_len );
-        if (status || ret_len != sizeof(ULONG)) return AVERROR( EINVAL );
-        if (!(ret = *(ULONG *)ret_ptr)) break;
-        memcpy( buffer, context->buffer, ret );
-        buffer += ret;
-        total += ret;
-        size -= ret;
-    } while (size && ret == context->buffer_size);
+        int step, buffer_offset = context->position % context->capacity;
+
+        if (!context->size && (ret = stream_context_read( context )) < 0) return ret;
+        if (!(step = min( size, context->size - buffer_offset ))) break;
+        memcpy( buffer, context->buffer + buffer_offset, step );
+        buffer += step;
+        total += step;
+        size -= step;
+
+        context->position += step;
+        if (!(context->position % context->capacity)) context->size = 0;
+    }

if (!total) return AVERROR_EOF;
-    context->position += total;
     return total;
 }

diff --git a/dlls/winedmo/unixlib.h b/dlls/winedmo/unixlib.h
index cf37bd5342a..b23f786fe47 100644
--- a/dlls/winedmo/unixlib.h
+++ b/dlls/winedmo/unixlib.h
@@ -40,10 +40,12 @@ struct process_attach_params

struct stream_context
 {
-    UINT64 stream;
-    UINT64 length;
-    UINT64 position;
-    UINT64 buffer_size;
+    UINT64 stream; /* client-side stream handle */
+    UINT64 length; /* total length of the stream */
+    UINT64 position; /* current position in the stream */
+
+    UINT32 capacity; /* total allocated capacity for the buffer */
+    UINT32 size; /* current data size in the buffer */
     BYTE buffer[];
 };