Keep bsinc filter quality more consistent between scales

This generates the filters using the proper size and scale. The 'a' divisor
should represent the +/- sample range (and thus be a whole number), with the
number of sample points being double that. Increasing the filter size to a
multiple of 4 (for SIMD) can be done by padding in 0s afterward.

1 files changed, 9 insertions, 7 deletions

diff --git a/utils/bsincgen.c b/utils/bsincgen.c
index 87bdd662..138f7a68 100644
--- a/utils/bsincgen.c
+++ b/utils/bsincgen.c
@@ -161,11 +161,9 @@ static void BsiGenerateTables()
     for(si = 0; si < BSINC_SCALE_COUNT; si++)

     {

         const double scale = scaleBase + (scaleRange * si / (BSINC_SCALE_COUNT - 1));

-        const double a = MinDouble(BSINC_POINTS_MIN, BSINC_POINTS_MIN / (2.0 * scale));

-        int m = 2 * (int)floor(a);

-

-        // Make sure the number of points is a multiple of 4 (for SSE).

-        m += ~(m - 1) & 3;

+        const double a = MinDouble(floor(BSINC_POINTS_MIN / (2.0 * scale)),

+                                   BSINC_POINTS_MIN);

+        int m = 2 * (int)a;

 

         mt[si] = m;

         at[si] = a;

@@ -241,6 +239,10 @@ static void BsiGenerateTables()
         }

     }

 

+    // Make sure the number of points is a multiple of 4 (for SIMD).

+    for(si = 0; si < BSINC_SCALE_COUNT; si++)

+        mt[si] = (mt[si]+3) & ~3;

+

     // Calculate the table size.

     i = 0;

     for(si = 0; si < BSINC_SCALE_COUNT; si++)

@@ -331,8 +333,8 @@ static void Sinc4GenerateTables(void)
     const double scaleBase = width / 2.0;

     const double scaleRange = 1.0 - scaleBase;

     const double scale = scaleBase + scaleRange;

-    const double a = MinDouble(4.0, 4.0 / (2.0*scale));

-    const int m = 2 * (int)floor(a);

+    const double a = MinDouble(4.0, floor(4.0 / (2.0*scale)));

+    const int m = 2 * (int)a;

     const int l = (m/2) - 1;

     int pi;

     for(pi = 0;pi < FRACTIONONE;pi++)