Re: [PATCH v17 0/2] MR2105: ddraw: Add local buffer in d3d_device7_DrawPrimitive()

[Zebediah Figura (＠zfigura)]

Zebediah Figura (@zfigura) commented about dlls/ddraw/device.c:
> -
>    device->ddraw_device_buffer.primitive_type = primitive_type;
> -
>    device->ddraw_device_buffer.fvf = fvf;
> -
>    device->ddraw_device_buffer.stride = stride;
> -
> -
>    /* We map & unmap directly.
> -
>     * That way, we only reserve the space and other calls will have a new one.
> -
>     * It should not happen, but let's be safe.
> -
>     *
> -
>     * We will fill it with following calls */
> -
>    wined3d_streaming_buffer_map(device->wined3d_device, &device->vertex_buffer, D3DMAXNUMVERTICES, stride,
> -
>        &device->ddraw_device_buffer.vertex_buffer_pos, (void**) &device->ddraw_device_buffer.buffer_vertices);
> -
>    wined3d_streaming_buffer_unmap(&device->vertex_buffer);
> -
> -
>    wined3d_streaming_buffer_map(device->wined3d_device, &device->index_buffer, D3DMAXNUMVERTICES, sizeof(*device->ddraw_device_buffer.buffer_indices),
> -
>        &device->ddraw_device_buffer.idx_buffer_pos, (void**) &device->ddraw_device_buffer.buffer_indices);
> -
>    wined3d_streaming_buffer_unmap(&device->index_buffer);

This isn't legal I'm afraid; you need to unmap *after* writing data to the buffer.

I also noticed a potential problem I hadn't considered when suggesting this approach: the streaming buffer is kind of a ring buffer, so if we run into the end, we'll need to flush before writing more data. Probably we should add an extra argument to wined3d_streaming_buffer_map() so it'll return an error if we're going to run over the end of the buffer.