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-rw-r--r--src/gallium/auxiliary/gallivm/lp_bld_arit.c84
1 files changed, 75 insertions, 9 deletions
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_arit.c b/src/gallium/auxiliary/gallivm/lp_bld_arit.c
index dce3c3745b..ff0c7f7ca8 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_arit.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_arit.c
@@ -614,17 +614,15 @@ lp_build_div(struct lp_build_context *bld,
/**
- * Linear interpolation.
- *
- * This also works for integer values with a few caveats.
+ * Linear interpolation -- without any checks.
*
* @sa http://www.stereopsis.com/doubleblend.html
*/
-LLVMValueRef
-lp_build_lerp(struct lp_build_context *bld,
- LLVMValueRef x,
- LLVMValueRef v0,
- LLVMValueRef v1)
+static INLINE LLVMValueRef
+lp_build_lerp_simple(struct lp_build_context *bld,
+ LLVMValueRef x,
+ LLVMValueRef v0,
+ LLVMValueRef v1)
{
LLVMValueRef delta;
LLVMValueRef res;
@@ -639,12 +637,80 @@ lp_build_lerp(struct lp_build_context *bld,
res = lp_build_add(bld, v0, res);
- if(bld->type.fixed)
+ if (bld->type.fixed) {
/* XXX: This step is necessary for lerping 8bit colors stored on 16bits,
* but it will be wrong for other uses. Basically we need a more
* powerful lp_type, capable of further distinguishing the values
* interpretation from the value storage. */
res = LLVMBuildAnd(bld->builder, res, lp_build_const_int_vec(bld->type, (1 << bld->type.width/2) - 1), "");
+ }
+
+ return res;
+}
+
+
+/**
+ * Linear interpolation.
+ */
+LLVMValueRef
+lp_build_lerp(struct lp_build_context *bld,
+ LLVMValueRef x,
+ LLVMValueRef v0,
+ LLVMValueRef v1)
+{
+ const struct lp_type type = bld->type;
+ LLVMValueRef res;
+
+ assert(lp_check_value(type, x));
+ assert(lp_check_value(type, v0));
+ assert(lp_check_value(type, v1));
+
+ if (type.norm) {
+ struct lp_type wide_type;
+ struct lp_build_context wide_bld;
+ LLVMValueRef xl, xh, v0l, v0h, v1l, v1h, resl, resh;
+ LLVMValueRef shift;
+
+ assert(type.length >= 2);
+ assert(!type.sign);
+
+ /*
+ * Create a wider type, enough to hold the intermediate result of the
+ * multiplication.
+ */
+ memset(&wide_type, 0, sizeof wide_type);
+ wide_type.fixed = TRUE;
+ wide_type.width = type.width*2;
+ wide_type.length = type.length/2;
+
+ lp_build_context_init(&wide_bld, bld->builder, wide_type);
+
+ lp_build_unpack2(bld->builder, type, wide_type, x, &xl, &xh);
+ lp_build_unpack2(bld->builder, type, wide_type, v0, &v0l, &v0h);
+ lp_build_unpack2(bld->builder, type, wide_type, v1, &v1l, &v1h);
+
+ /*
+ * Scale x from [0, 255] to [0, 256]
+ */
+
+ shift = lp_build_const_int_vec(wide_type, type.width - 1);
+
+ xl = lp_build_add(&wide_bld, xl,
+ LLVMBuildAShr(bld->builder, xl, shift, ""));
+ xh = lp_build_add(&wide_bld, xh,
+ LLVMBuildAShr(bld->builder, xh, shift, ""));
+
+ /*
+ * Lerp both halves.
+ */
+
+ resl = lp_build_lerp_simple(&wide_bld, xl, v0l, v1l);
+ resh = lp_build_lerp_simple(&wide_bld, xh, v0h, v1h);
+
+ res = lp_build_pack2(bld->builder, wide_type, type, resl, resh);
+ } else {
+ res = lp_build_lerp_simple(bld, x, v0, v1);
+ }
return res;
}