diff options
| -rw-r--r-- | src/gallium/auxiliary/gallivm/lp_bld_conv.c | 59 |
1 files changed, 34 insertions, 25 deletions
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_conv.c b/src/gallium/auxiliary/gallivm/lp_bld_conv.c index c43ee8ac638..c261d761161 100644 --- a/src/gallium/auxiliary/gallivm/lp_bld_conv.c +++ b/src/gallium/auxiliary/gallivm/lp_bld_conv.c @@ -231,44 +231,53 @@ lp_build_unsigned_norm_to_float(struct gallivm_state *gallivm, assert(dst_type.floating); - /* Special-case int8->float, though most cases could be handled - * this way: - */ - if (src_width == 8) { - scale = 1.0/255.0; + mantissa = lp_mantissa(dst_type); + + if (src_width <= (mantissa + 1)) { + /* + * The source width matches fits 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. + */ + + scale = 1.0/(double)((1ULL << src_width) - 1); res = LLVMBuildSIToFP(builder, src, vec_type, ""); res = LLVMBuildFMul(builder, res, lp_build_const_vec(gallivm, dst_type, scale), ""); return res; } + else { + /* + * The source width exceeds what can be represented in floating + * point. So truncate the incoming values. + */ - mantissa = lp_mantissa(dst_type); - - n = MIN2(mantissa, src_width); + n = MIN2(mantissa, src_width); - ubound = ((unsigned long long)1 << n); - mask = ubound - 1; - scale = (double)ubound/mask; - bias = (double)((unsigned long long)1 << (mantissa - n)); + ubound = ((unsigned long long)1 << n); + mask = ubound - 1; + scale = (double)ubound/mask; + bias = (double)((unsigned long long)1 << (mantissa - n)); - res = src; + res = src; - if(src_width > mantissa) { - int shift = src_width - mantissa; - res = LLVMBuildLShr(builder, res, - lp_build_const_int_vec(gallivm, dst_type, shift), ""); - } + if (src_width > mantissa) { + int shift = src_width - mantissa; + res = LLVMBuildLShr(builder, res, + lp_build_const_int_vec(gallivm, dst_type, shift), ""); + } - bias_ = lp_build_const_vec(gallivm, dst_type, bias); + bias_ = lp_build_const_vec(gallivm, dst_type, bias); - res = LLVMBuildOr(builder, - res, - LLVMBuildBitCast(builder, bias_, int_vec_type, ""), ""); + res = LLVMBuildOr(builder, + res, + LLVMBuildBitCast(builder, bias_, int_vec_type, ""), ""); - res = LLVMBuildBitCast(builder, res, vec_type, ""); + res = LLVMBuildBitCast(builder, res, vec_type, ""); - res = LLVMBuildFSub(builder, res, bias_, ""); - res = LLVMBuildFMul(builder, res, lp_build_const_vec(gallivm, dst_type, scale), ""); + res = LLVMBuildFSub(builder, res, bias_, ""); + res = LLVMBuildFMul(builder, res, lp_build_const_vec(gallivm, dst_type, scale), ""); + } return res; } |