fixed point resampling option

components/codecs/component.mk

@@ -9,6 +9,7 @@ COMPONENT_ADD_LDFLAGS=-l$(COMPONENT_NAME) 	\
 	$(COMPONENT_PATH)/lib/libvorbisidec.a	\
 	$(COMPONENT_PATH)/lib/libogg.a			\
 	$(COMPONENT_PATH)/lib/libalac.a			\
+	$(COMPONENT_PATH)/lib/libresample16.a		\
 	$(COMPONENT_PATH)/lib/libsoxr.a
 	
 	

components/codecs/inc/resample16/resample16.h

@@ -0,0 +1,85 @@
+/*
+ * FILE: resample16.h
+ *
+ * The configuration constants below govern
+ * the number of bits in the input sample and filter coefficients, the 
+ * number of bits to the right of the binary-point for fixed-point math, etc.
+ *
+ */
+
+/* Conversion constants */
+#define Nhc       8
+#define Na        7
+#define Np       (Nhc+Na)
+#define Npc      (1<<Nhc)
+#define Amask    ((1<<Na)-1)
+#define Pmask    ((1<<Np)-1)
+#define Nh       16
+#define Nb       16
+#define Nhxn     14
+#define Nhg      (Nh-Nhxn)
+#define NLpScl   13
+
+/* Description of constants:
+ *
+ * Npc - is the number of look-up values available for the lowpass filter
+ *    between the beginning of its impulse response and the "cutoff time"
+ *    of the filter.  The cutoff time is defined as the reciprocal of the
+ *    lowpass-filter cut off frequence in Hz.  For example, if the
+ *    lowpass filter were a sinc function, Npc would be the index of the
+ *    impulse-response lookup-table corresponding to the first zero-
+ *    crossing of the sinc function.  (The inverse first zero-crossing
+ *    time of a sinc function equals its nominal cutoff frequency in Hz.)
+ *    Npc must be a power of 2 due to the details of the current
+ *    implementation. The default value of 512 is sufficiently high that
+ *    using linear interpolation to fill in between the table entries
+ *    gives approximately 16-bit accuracy in filter coefficients.
+ *
+ * Nhc - is log base 2 of Npc.
+ *
+ * Na - is the number of bits devoted to linear interpolation of the
+ *    filter coefficients.
+ *
+ * Np - is Na + Nhc, the number of bits to the right of the binary point
+ *    in the integer "time" variable. To the left of the point, it indexes
+ *    the input array (X), and to the right, it is interpreted as a number
+ *    between 0 and 1 sample of the input X.  Np must be less than 16 in
+ *    this implementation.
+ *
+ * Nh - is the number of bits in the filter coefficients. The sum of Nh and
+ *    the number of bits in the input data (typically 16) cannot exceed 32.
+ *    Thus Nh should be 16.  The largest filter coefficient should nearly
+ *    fill 16 bits (32767).
+ *
+ * Nb - is the number of bits in the input data. The sum of Nb and Nh cannot
+ *    exceed 32.
+ *
+ * Nhxn - is the number of bits to right shift after multiplying each input
+ *    sample times a filter coefficient. It can be as great as Nh and as
+ *    small as 0. Nhxn = Nh-2 gives 2 guard bits in the multiply-add
+ *    accumulation.  If Nhxn=0, the accumulation will soon overflow 32 bits.
+ *
+ * Nhg - is the number of guard bits in mpy-add accumulation (equal to Nh-Nhxn)
+ *
+ * NLpScl - is the number of bits allocated to the unity-gain normalization
+ *    factor.  The output of the lowpass filter is multiplied by LpScl and
+ *    then right-shifted NLpScl bits. To avoid overflow, we must have 
+ *    Nb+Nhg+NLpScl < 32.
+ */
+
+typedef char           BOOL;
+typedef short          HWORD;
+typedef unsigned short UHWORD;
+typedef int            WORD;
+typedef unsigned int   UWORD;
+
+struct resample16_s;
+
+typedef enum { RESAMPLE16_FAST, RESAMPLE16_SMALL, RESAMPLE16_LARGE, RESAMPLE_CUSTOM } resample16_filter_e;
+
+WORD 				resample16(struct resample16_s *r, HWORD X[],	int inCount, HWORD Y[]);
+struct resample16_s*  resample16_create(double factor, resample16_filter_e filter, BOOL interp);
+void 				resample16_delete(struct resample16_s *r);
+void 				resample16_flush(struct resample16_s *r);
+
+