fix an overflow in SPI_VS_OUT_CONFIG

VS must always export at least 1 param.

diff --git a/src/mesa/drivers/dri/r600/r700_vertprog.c b/src/mesa/drivers/dri/r600/r700_vertprog.c
index a827de1..ecb7254 100644 (file)
--- a/src/mesa/drivers/dri/r600/r700_vertprog.c
+++ b/src/mesa/drivers/dri/r600/r700_vertprog.c
@@ -383,7 +383,7 @@ GLboolean r700SetupVertexProgram(GLcontext * ctx)
                  STACK_SIZE_shift, STACK_SIZE_mask);
     }
 
-    SETfield(r700->SPI_VS_OUT_CONFIG.u32All, vp->r700Shader.nParamExports - 1,
+    SETfield(r700->SPI_VS_OUT_CONFIG.u32All, vp->r700Shader.nParamExports ? (vp->r700Shader.nParamExports - 1) : 0,
              VS_EXPORT_COUNT_shift, VS_EXPORT_COUNT_mask);
        SETfield(r700->SPI_PS_IN_CONTROL_0.u32All, vp->r700Shader.nParamExports,
              NUM_INTERP_shift, NUM_INTERP_mask);