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-rw-r--r--src/gallium/auxiliary/gallivm/lp_bld_conv.c59
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 c43ee8ac63..c261d76116 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;
}