Small math optimizations for dsp::smooth_cubic_linear and dsp::smooth_cubic_log functions.

Author: sadko4u

CHANGELOG

@@ -3,7 +3,8 @@
 *******************************************************************************
 
 === 1.0.11 ===
-
+* Small math optimizations for dsp::smooth_cubic_linear and dsp::smooth_cubic_log
+  functions.
 
 === 1.0.10 ===
 * ARM NEON-optimized code compiles now only for at least ARMv6 architecture.

include/private/dsp/arch/generic/graphics/interpolation.h

@@ -32,28 +32,28 @@ namespace lsp
     {
         void smooth_cubic_linear(float *dst, float start, float stop, size_t count)
         {
-            float dy = stop - start;
+            float dy = 2.0f * (stop - start);
             float nx = 1.0f / (count + 1); // Normalizing x
 
             for (size_t i=0; i<count; ++i)
             {
                 float x = i * nx;
-                *(dst++) = start + dy * x*x * (3.0f - 2.0f * x);
+                *(dst++) = start + dy * x*x * (1.5f - x);
             }
         }
 
         void smooth_cubic_log(float *dst, float start, float stop, size_t count)
         {
-            float dy = logf(stop/start);
+            float dy = 2.0f * logf(stop/start);
             float nx = 1.0f / (count + 1); // Normalizing x
 
             for (size_t i=0; i<count; ++i)
             {
                 float x = i * nx;
-                *(dst++) = start * expf(dy * x*x * (3.0f - 2.0f * x));
+                *(dst++) = start * expf(dy * x*x * (1.5f - x));
             }
         }
-    }
-}
+    } /* namespace generic */
+} /* namespace lsp */
 
 #endif /* PRIVATE_DSP_ARCH_GENERIC_GRAPHICS_INTERPOLATION_H_ */