[Mesa-dev] [PATCH] llvmpipe: Fix PIPE_FORMAT_Z32_FLOAT_S8X24_UINT handling for big-endian.

[Richard Sandiford]

llvmpipe treats PIPE_FORMAT_Z32_FLOAT_S8X24_UINT as a bit of a special case,
handling it as two 32-bit pieces rather than a single 64-bit block:

   /* 64bit d/s format is special already extracted 32 bits */
   total_bits = format_desc->block.bits > 32 ? 32 : format_desc->block.bits;

The format_desc describes the whole 64-bit block, so the z shift
will be 32 for big-endian.  But since we're accessing the z channel
as a 32-bit value rather than a 64-bit value, we need to mask the shift
with 31.

Signed-off-by: Richard Sandiford <rsandifo at linux.vnet.ibm.com>
---
 src/gallium/drivers/llvmpipe/lp_bld_depth.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/llvmpipe/lp_bld_depth.c b/src/gallium/drivers/llvmpipe/lp_bld_depth.c
index 5c13ee5..b6c32ff 100644
--- a/src/gallium/drivers/llvmpipe/lp_bld_depth.c
+++ b/src/gallium/drivers/llvmpipe/lp_bld_depth.c
@@ -363,7 +363,8 @@ get_z_shift_and_mask(const struct util_format_description *format_desc,
       return FALSE;
 
    *width = format_desc->channel[z_swizzle].size;
-   *shift = format_desc->channel[z_swizzle].shift;
+   /* & 31 is for the same reason as the 32-bit limit above */
+   *shift = format_desc->channel[z_swizzle].shift & 31;
 
    if (*width == total_bits) {
       *mask = 0xffffffff;
-- 
1.8.3.1