Merging the postbeta2 branch onto the mainline.

Monty

svn path=/trunk/vorbis/; revision=729

1 files changed, 92 insertions, 0 deletions

diff --git a/lib/lookup.c b/lib/lookup.c
new file mode 100644
index 00000000..ec533b5e
--- /dev/null
+++ b/lib/lookup.c
@@ -0,0 +1,92 @@
+/********************************************************************
+ *                                                                  *
+ * THIS FILE IS PART OF THE Ogg Vorbis SOFTWARE CODEC SOURCE CODE.  *
+ * USE, DISTRIBUTION AND REPRODUCTION OF THIS SOURCE IS GOVERNED BY *
+ * THE GNU PUBLIC LICENSE 2, WHICH IS INCLUDED WITH THIS SOURCE.    *
+ * PLEASE READ THESE TERMS DISTRIBUTING.                            *
+ *                                                                  *
+ * THE OggSQUISH SOURCE CODE IS (C) COPYRIGHT 1994-2000             *
+ * by Monty <monty@xiph.org> and The XIPHOPHORUS Company            *
+ * http://www.xiph.org/                                             *
+ *                                                                  *
+ ********************************************************************
+
+  function: lookup based functions
+  last mod: $Id: lookup.c,v 1.2 2000/10/12 03:12:53 xiphmont Exp $
+
+ ********************************************************************/
+
+#include <math.h>
+#include "lookup.h"
+#include "lookup_data.h"
+
+#ifdef FLOAT_LOOKUP
+
+/* interpolated lookup based cos function, domain 0 to PI only */
+float vorbis_coslook(float a){
+  float d=a*(.31830989*(float)COS_LOOKUP_SZ);
+  int i=d;
+  return COS_LOOKUP[i]+ (d-i)*(COS_LOOKUP[i+1]-COS_LOOKUP[i]);
+}
+
+/* interpolated 1./sqrt(p) where .5 <= p < 1. */
+float vorbis_invsqlook(float a){
+  float d=a*(2.*(float)INVSQ_LOOKUP_SZ)-(float)INVSQ_LOOKUP_SZ;
+  int i=d;
+  return INVSQ_LOOKUP[i]+ (d-i)*(INVSQ_LOOKUP[i+1]-INVSQ_LOOKUP[i]);
+}
+
+/* interpolated 1./sqrt(p) where .5 <= p < 1. */
+float vorbis_invsq2explook(int a){
+  return INVSQ2EXP_LOOKUP[a-INVSQ2EXP_LOOKUP_MIN];
+}
+
+#include <stdio.h>
+/* interpolated lookup based fromdB function, domain -140dB to 0dB only */
+float vorbis_fromdBlook(float a){
+  int i=a*((float)(-(1<<FROMdB2_SHIFT)));
+  return (i<0)?1.:
+    ((i>=(FROMdB_LOOKUP_SZ<<FROMdB_SHIFT))?0.:
+     FROMdB_LOOKUP[i>>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]);
+}
+
+#endif
+
+#ifdef INT_LOOKUP
+/* interpolated 1./sqrt(p) where .5 <= a < 1. (.100000... to .111111...) in
+   16.16 format 
+
+   returns in m.8 format */
+long vorbis_invsqlook_i(long a,long e){
+  long i=(a&0x7fff)>>(INVSQ_LOOKUP_I_SHIFT-1); 
+  long d=(a&INVSQ_LOOKUP_I_MASK)<<(16-INVSQ_LOOKUP_I_SHIFT); /*  0.16 */
+  long val=INVSQ_LOOKUP_I[i]-                                /*  1.16 */
+    (((INVSQ_LOOKUP_I[i]-INVSQ_LOOKUP_I[i+1])*               /*  0.16 */
+      d)>>16);                                               /* result 1.16 */
+  
+  e+=32;
+  if(e&1)val=(val*5792)>>13; /* multiply val by 1/sqrt(2) */
+  e=(e>>1)-8;
+
+  return(val>>e);
+}
+
+/* interpolated lookup based fromdB function, domain -140dB to 0dB only */
+/* a is in n.12 format */
+float vorbis_fromdBlook_i(long a){
+  int i=(-a)>>(12-FROMdB2_SHIFT);
+  return (i<0)?1.:
+    ((i>=(FROMdB_LOOKUP_SZ<<FROMdB_SHIFT))?0.:
+     FROMdB_LOOKUP[i>>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]);
+}
+
+/* interpolated lookup based cos function, domain 0 to PI only */
+/* a is in 0.16 format, where 0==0, 2^^16-1==PI, return 0.14 */
+long vorbis_coslook_i(long a){
+  int i=a>>COS_LOOKUP_I_SHIFT;
+  int d=a&COS_LOOKUP_I_MASK;
+  return COS_LOOKUP_I[i]- ((d*(COS_LOOKUP_I[i]-COS_LOOKUP_I[i+1]))>>
+			   COS_LOOKUP_I_SHIFT);
+}
+
+#endif