Mercurial > vec

changeset 26:6c91cd9a2f2d

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
include/vec/vec: fix vec_avg implementation now it's exactly the same as AltiVec's
author Paper <paper@tflc.us>
date Mon, 25 Nov 2024 04:43:22 +0000
parents 92156fe32755
children d00b95f95dd1
files include/vec/vec.h
diffstat 1 files changed, 7 insertions(+), 12 deletions(-) [+]
line wrap: on
line diff
--- a/include/vec/vec.h	Sun Nov 24 11:15:59 2024 +0000
+++ b/include/vec/vec.h	Mon Nov 25 04:43:22 2024 +0000
@@ -239,19 +239,14 @@
 
 inline vec_intmax vec_avg(vec_intmax x, vec_intmax y)
 {
-    if ((x < 0) == (y < 0)) { // same sign
-        // this gets the equivalent of:
-        // vec_int32 r = ((vec_int64)x + (vec_int64)y) / 2;
-        vec_intmax r = (x / 2) + (y / 2) + (((x % 2) + (y % 2)) / 2);
-
-        // FIXME emulate AltiVec quirks
+    vec_intmax x_d_quot   = (x / 2);
+    vec_intmax x_d_rem    = (x % 2);
+    vec_intmax y_d_quot   = (y / 2);
+    vec_intmax y_d_rem    = (y % 2);
+    vec_intmax rem_d_quot = ((x_d_rem + y_d_rem) / 2);
+    vec_intmax rem_d_rem  = ((x_d_rem + y_d_rem) % 2);
 
-        return r;
-    } else {
-        vec_intmax r = (x + y) / 2;
-        // FIXME emulate AltiVec quirks
-        return r;
-    }
+    return (x_d_quot + y_d_quot) + (rem_d_quot) + (rem_d_rem == 1);
 }
 
 inline vec_uintmax vec_uavg(vec_uintmax x, vec_uintmax y)