Module: Mesa Branch: master Commit: b1ed7202dfb64c01313e78bd4fe290ecd08bf5f7 URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=b1ed7202dfb64c01313e78bd4fe290ecd08bf5f7
Author: Roland Scheidegger <[email protected]> Date: Wed Jul 31 16:57:50 2013 +0200 gallivm: use nearest rounding for float->unorm24 conversion Previously we were using truncation, which gives the correct result only for numbers in [0.5-1.0] range (because there's no mantissa bits to do any rounding there). This is frequently hit (and probably only used there) when converting fragment depth to depth format (d24s8 etc.) or otherwise dealing with depth format. v2: as spotted by Jose, get rid of extra type (src_type is already unsigned). Reviewed-by: Jose Fonseca <[email protected]> --- src/gallium/auxiliary/gallivm/lp_bld_conv.c | 10 ++++++---- 1 files changed, 6 insertions(+), 4 deletions(-) diff --git a/src/gallium/auxiliary/gallivm/lp_bld_conv.c b/src/gallium/auxiliary/gallivm/lp_bld_conv.c index ba51ff7..712ce5f 100644 --- a/src/gallium/auxiliary/gallivm/lp_bld_conv.c +++ b/src/gallium/auxiliary/gallivm/lp_bld_conv.c @@ -266,17 +266,19 @@ lp_build_clamped_float_to_unsigned_norm(struct gallivm_state *gallivm, else if (dst_width == (mantissa + 1)) { /* * The destination width matches exactly what can be represented in - * floating point (i.e., mantissa + 1 bits). So do a straight - * multiplication followed by casting. No further rounding is necessary. + * floating point (i.e., mantissa + 1 bits). Even so correct rounding + * still needs to be applied (only for numbers in [0.5-1.0] would + * conversion using truncation after scaling be sufficient). */ - double scale; + struct lp_build_context uf32_bld; + lp_build_context_init(&uf32_bld, gallivm, src_type); scale = (double)((1ULL << dst_width) - 1); res = LLVMBuildFMul(builder, src, lp_build_const_vec(gallivm, src_type, scale), ""); - res = LLVMBuildFPToSI(builder, res, int_vec_type, ""); + res = lp_build_iround(&uf32_bld, res); } else { /* _______________________________________________ mesa-commit mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/mesa-commit
