/* audioopmodule - Module to detect peak values in arrays */

#include "Python.h"

#if SIZEOF_INT == 4

typedef int Py_Int32;

typedef unsigned int Py_UInt32;

#else

#if SIZEOF_LONG == 4

typedef long Py_Int32;

typedef unsigned long Py_UInt32;

#else

#error "No 4-byte integral type"

#endif

#endif

typedef short PyInt16;

#if defined(__CHAR_UNSIGNED__)

#if defined(signed)

/* This module currently does not work on systems where only unsigned

characters are available. Take it out of Setup. Sorry. */

#endif

#endif

/* Code shamelessly stolen from sox, 12.17.7, g711.c

** (c) Craig Reese, Joe Campbell and Jeff Poskanzer 1989 */

/* From g711.c:

*

* December 30, 1994:

* Functions linear2alaw, linear2ulaw have been updated to correctly

* convert unquantized 16 bit values.

* Tables for direct u- to A-law and A- to u-law conversions have been

* corrected.

* Borge Lindberg, Center for PersonKommunikation, Aalborg University.

* [email protected]

*

*/

#define BIAS 0x84 /* define the add-in bias for 16 bit samples */

#define CLIP 32635

#define SIGN_BIT (0x80) /* Sign bit for a A-law byte. */

#define QUANT_MASK (0xf) /* Quantization field mask. */

#define SEG_SHIFT (4) /* Left shift for segment number. */

#define SEG_MASK (0x70) /* Segment field mask. */

static PyInt16 seg_aend[8] = {0x1F, 0x3F, 0x7F, 0xFF,

0x1FF, 0x3FF, 0x7FF, 0xFFF};

static PyInt16 seg_uend[8] = {0x3F, 0x7F, 0xFF, 0x1FF,

0x3FF, 0x7FF, 0xFFF, 0x1FFF};

static PyInt16

search(PyInt16 val, PyInt16 *table, int size)

{

int i;

for (i = 0; i < size; i++) {

if (val <= *table++)

return (i);

}

return (size);

}

#define st_ulaw2linear16(uc) (_st_ulaw2linear16[uc])

#define st_alaw2linear16(uc) (_st_alaw2linear16[uc])

static PyInt16 _st_ulaw2linear16[256] = {

-32124, -31100, -30076, -29052, -28028, -27004, -25980,

-24956, -23932, -22908, -21884, -20860, -19836, -18812,

-17788, -16764, -15996, -15484, -14972, -14460, -13948,

-13436, -12924, -12412, -11900, -11388, -10876, -10364,

-9852, -9340, -8828, -8316, -7932, -7676, -7420,

-7164, -6908, -6652, -6396, -6140, -5884, -5628,

-5372, -5116, -4860, -4604, -4348, -4092, -3900,

-3772, -3644, -3516, -3388, -3260, -3132, -3004,

-2876, -2748, -2620, -2492, -2364, -2236, -2108,

-1980, -1884, -1820, -1756, -1692, -1628, -1564,

-1500, -1436, -1372, -1308, -1244, -1180, -1116,

-1052, -988, -924, -876, -844, -812, -780,

-748, -716, -684, -652, -620, -588, -556,

-524, -492, -460, -428, -396, -372, -356,

-340, -324, -308, -292, -276, -260, -244,

-228, -212, -196, -180, -164, -148, -132,

-120, -112, -104, -96, -88, -80, -72,

-64, -56, -48, -40, -32, -24, -16,

-8, 0, 32124, 31100, 30076, 29052, 28028,

27004, 25980, 24956, 23932, 22908, 21884, 20860,

19836, 18812, 17788, 16764, 15996, 15484, 14972,

14460, 13948, 13436, 12924, 12412, 11900, 11388,

10876, 10364, 9852, 9340, 8828, 8316, 7932,

7676, 7420, 7164, 6908, 6652, 6396, 6140,

5884, 5628, 5372, 5116, 4860, 4604, 4348,

4092, 3900, 3772, 3644, 3516, 3388, 3260,

3132, 3004, 2876, 2748, 2620, 2492, 2364,

2236, 2108, 1980, 1884, 1820, 1756, 1692,

1628, 1564, 1500, 1436, 1372, 1308, 1244,

1180, 1116, 1052, 988, 924, 876, 844,

812, 780, 748, 716, 684, 652, 620,

588, 556, 524, 492, 460, 428, 396,

372, 356, 340, 324, 308, 292, 276,

260, 244, 228, 212, 196, 180, 164,

148, 132, 120, 112, 104, 96, 88,

80, 72, 64, 56, 48, 40, 32,

24, 16, 8, 0

};

/*

* linear2ulaw() accepts a 14-bit signed integer and encodes it as u-law data

* stored in a unsigned char. This function should only be called with

* the data shifted such that it only contains information in the lower

* 14-bits.

*

* In order to simplify the encoding process, the original linear magnitude

* is biased by adding 33 which shifts the encoding range from (0 - 8158) to

* (33 - 8191). The result can be seen in the following encoding table:

*

* Biased Linear Input Code Compressed Code

* ------------------------ ---------------

* 00000001wxyza 000wxyz

* 0000001wxyzab 001wxyz

* 000001wxyzabc 010wxyz

* 00001wxyzabcd 011wxyz

* 0001wxyzabcde 100wxyz

* 001wxyzabcdef 101wxyz

* 01wxyzabcdefg 110wxyz

* 1wxyzabcdefgh 111wxyz

*

* Each biased linear code has a leading 1 which identifies the segment

* number. The value of the segment number is equal to 7 minus the number

* of leading 0's. The quantization interval is directly available as the

* four bits wxyz. * The trailing bits (a - h) are ignored.

*

* Ordinarily the complement of the resulting code word is used for

* transmission, and so the code word is complemented before it is returned.

*

* For further information see John C. Bellamy's Digital Telephony, 1982,

* John Wiley & Sons, pps 98-111 and 472-476.

*/

static unsigned char

st_14linear2ulaw(PyInt16 pcm_val) /* 2's complement (14-bit range) */

{

PyInt16 mask;

PyInt16 seg;

unsigned char uval;

/* The original sox code does this in the calling function, not here */

pcm_val = pcm_val >> 2;

/* u-law inverts all bits */

/* Get the sign and the magnitude of the value. */

if (pcm_val < 0) {

pcm_val = -pcm_val;

mask = 0x7F;

} else {

mask = 0xFF;

}

if ( pcm_val > CLIP ) pcm_val = CLIP; /* clip the magnitude */

pcm_val += (BIAS >> 2);

/* Convert the scaled magnitude to segment number. */

seg = search(pcm_val, seg_uend, 8);

/*

* Combine the sign, segment, quantization bits;

* and complement the code word.

*/

if (seg >= 8) /* out of range, return maximum value. */

return (unsigned char) (0x7F ^ mask);

else {

uval = (unsigned char) (seg << 4) | ((pcm_val >> (seg + 1)) & 0xF);

return (uval ^ mask);

}

}

static PyInt16 _st_alaw2linear16[256] = {

-5504, -5248, -6016, -5760, -4480, -4224, -4992,

-4736, -7552, -7296, -8064, -7808, -6528, -6272,

-7040, -6784, -2752, -2624, -3008, -2880, -2240,

-2112, -2496, -2368, -3776, -3648, -4032, -3904,

-3264, -3136, -3520, -3392, -22016, -20992, -24064,

-23040, -17920, -16896, -19968, -18944, -30208, -29184,

-32256, -31232, -26112, -25088, -28160, -27136, -11008,

-10496, -12032, -11520, -8960, -8448, -9984, -9472,

-15104, -14592, -16128, -15616, -13056, -12544, -14080,

-13568, -344, -328, -376, -360, -280, -264,

-312, -296, -472, -456, -504, -488, -408,

-392, -440, -424, -88, -72, -120, -104,

-24, -8, -56, -40, -216, -200, -248,

-232, -152, -136, -184, -168, -1376, -1312,

-1504, -1440, -1120, -1056, -1248, -1184, -1888,

-1824, -2016, -1952, -1632, -1568, -1760, -1696,

-688, -656, -752, -720, -560, -528, -624,

-592, -944, -912, -1008, -976, -816, -784,

-880, -848, 5504, 5248, 6016, 5760, 4480,

4224, 4992, 4736, 7552, 7296, 8064, 7808,

6528, 6272, 7040, 6784, 2752, 2624, 3008,

2880, 2240, 2112, 2496, 2368, 3776, 3648,

4032, 3904, 3264, 3136, 3520, 3392, 22016,

20992, 24064, 23040, 17920, 16896, 19968, 18944,

30208, 29184, 32256, 31232, 26112, 25088, 28160,

27136, 11008, 10496, 12032, 11520, 8960, 8448,

9984, 9472, 15104, 14592, 16128, 15616, 13056,

12544, 14080, 13568, 344, 328, 376, 360,

280, 264, 312, 296, 472, 456, 504,

488, 408, 392, 440, 424, 88, 72,

120, 104, 24, 8, 56, 40, 216,

200, 248, 232, 152, 136, 184, 168,

1376, 1312, 1504, 1440, 1120, 1056, 1248,

1184, 1888, 1824, 2016, 1952, 1632, 1568,

1760, 1696, 688, 656, 752, 720, 560,

528, 624, 592, 944, 912, 1008, 976,

816, 784, 880, 848

};

/*

* linear2alaw() accepts an 13-bit signed integer and encodes it as A-law data

* stored in a unsigned char. This function should only be called with

* the data shifted such that it only contains information in the lower

* 13-bits.

*

* Linear Input Code Compressed Code

* ------------------------ ---------------

* 0000000wxyza 000wxyz

* 0000001wxyza 001wxyz

* 000001wxyzab 010wxyz

* 00001wxyzabc 011wxyz

* 0001wxyzabcd 100wxyz

* 001wxyzabcde 101wxyz

* 01wxyzabcdef 110wxyz

* 1wxyzabcdefg 111wxyz

*

* For further information see John C. Bellamy's Digital Telephony, 1982,

* John Wiley & Sons, pps 98-111 and 472-476.

*/

static unsigned char

st_linear2alaw(PyInt16 pcm_val) /* 2's complement (13-bit range) */

{

PyInt16 mask;

short seg;

unsigned char aval;

/* The original sox code does this in the calling function, not here */

pcm_val = pcm_val >> 3;

/* A-law using even bit inversion */

if (pcm_val >= 0) {

mask = 0xD5; /* sign (7th) bit = 1 */

} else {

mask = 0x55; /* sign bit = 0 */

pcm_val = -pcm_val - 1;

}

/* Convert the scaled magnitude to segment number. */

seg = search(pcm_val, seg_aend, 8);

/* Combine the sign, segment, and quantization bits. */

if (seg >= 8) /* out of range, return maximum value. */

return (unsigned char) (0x7F ^ mask);

else {

aval = (unsigned char) seg << SEG_SHIFT;

if (seg < 2)

aval |= (pcm_val >> 1) & QUANT_MASK;

else

aval |= (pcm_val >> seg) & QUANT_MASK;

return (aval ^ mask);

}

}

/* End of code taken from sox */

/* Intel ADPCM step variation table */

static int indexTable[16] = {

-1, -1, -1, -1, 2, 4, 6, 8,

-1, -1, -1, -1, 2, 4, 6, 8,

};

static int stepsizeTable[89] = {

7, 8, 9, 10, 11, 12, 13, 14, 16, 17,

19, 21, 23, 25, 28, 31, 34, 37, 41, 45,

50, 55, 60, 66, 73, 80, 88, 97, 107, 118,

130, 143, 157, 173, 190, 209, 230, 253, 279, 307,

337, 371, 408, 449, 494, 544, 598, 658, 724, 796,

876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,

2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,

5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,

15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767

};

#define CHARP(cp, i) ((signed char *)(cp+i))

#define SHORTP(cp, i) ((short *)(cp+i))

#define LONGP(cp, i) ((Py_Int32 *)(cp+i))

static PyObject *AudioopError;

static PyObject *

audioop_getsample(PyObject *self, PyObject *args)

{

signed char *cp;

int len, size, val = 0;

int i;

if ( !PyArg_ParseTuple(args, "s#ii:getsample", &cp, &len, &size, &i) )

return 0;

if ( size != 1 && size != 2 && size != 4 ) {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

if ( i < 0 || i >= len/size ) {

PyErr_SetString(AudioopError, "Index out of range");

return 0;

}

if ( size == 1 ) val = (int)*CHARP(cp, i);

else if ( size == 2 ) val = (int)*SHORTP(cp, i*2);

else if ( size == 4 ) val = (int)*LONGP(cp, i*4);

return PyInt_FromLong(val);

}

static PyObject *

audioop_max(PyObject *self, PyObject *args)

{

signed char *cp;

int len, size, val = 0;

int i;

int max = 0;

if ( !PyArg_ParseTuple(args, "s#i:max", &cp, &len, &size) )

return 0;

if ( size != 1 && size != 2 && size != 4 ) {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

for ( i=0; i<len; i+= size) {

if ( size == 1 ) val = (int)*CHARP(cp, i);

else if ( size == 2 ) val = (int)*SHORTP(cp, i);

else if ( size == 4 ) val = (int)*LONGP(cp, i);

if ( val < 0 ) val = (-val);

if ( val > max ) max = val;

}

return PyInt_FromLong(max);

}

static PyObject *

audioop_minmax(PyObject *self, PyObject *args)

{

signed char *cp;

int len, size, val = 0;

int i;

int min = 0x7fffffff, max = -0x7fffffff;

if (!PyArg_ParseTuple(args, "s#i:minmax", &cp, &len, &size))

return NULL;

if (size != 1 && size != 2 && size != 4) {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return NULL;

}

for (i = 0; i < len; i += size) {

if (size == 1) val = (int) *CHARP(cp, i);

else if (size == 2) val = (int) *SHORTP(cp, i);

else if (size == 4) val = (int) *LONGP(cp, i);

if (val > max) max = val;

if (val < min) min = val;

}

return Py_BuildValue("(ii)", min, max);

}

static PyObject *

audioop_avg(PyObject *self, PyObject *args)

{

signed char *cp;

int len, size, val = 0;

int i;

double avg = 0.0;

if ( !PyArg_ParseTuple(args, "s#i:avg", &cp, &len, &size) )

return 0;

if ( size != 1 && size != 2 && size != 4 ) {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

for ( i=0; i<len; i+= size) {

if ( size == 1 ) val = (int)*CHARP(cp, i);

else if ( size == 2 ) val = (int)*SHORTP(cp, i);

else if ( size == 4 ) val = (int)*LONGP(cp, i);

avg += val;

}

if ( len == 0 )

val = 0;

else

val = (int)(avg / (double)(len/size));

return PyInt_FromLong(val);

}

static PyObject *

audioop_rms(PyObject *self, PyObject *args)

{

signed char *cp;

int len, size, val = 0;

int i;

double sum_squares = 0.0;

if ( !PyArg_ParseTuple(args, "s#i:rms", &cp, &len, &size) )

return 0;

if ( size != 1 && size != 2 && size != 4 ) {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

for ( i=0; i<len; i+= size) {

if ( size == 1 ) val = (int)*CHARP(cp, i);

else if ( size == 2 ) val = (int)*SHORTP(cp, i);

else if ( size == 4 ) val = (int)*LONGP(cp, i);

sum_squares += (double)val*(double)val;

}

if ( len == 0 )

val = 0;

else

val = (int)sqrt(sum_squares / (double)(len/size));

return PyInt_FromLong(val);

}

static double _sum2(short *a, short *b, int len)

{

int i;

double sum = 0.0;

for( i=0; i<len; i++) {

sum = sum + (double)a[i]*(double)b[i];

}

return sum;

}

/*

** Findfit tries to locate a sample within another sample. Its main use

** is in echo-cancellation (to find the feedback of the output signal in

** the input signal).

** The method used is as follows:

**

** let R be the reference signal (length n) and A the input signal (length N)

** with N > n, and let all sums be over i from 0 to n-1.

**

** Now, for each j in {0..N-n} we compute a factor fj so that -fj*R matches A

** as good as possible, i.e. sum( (A[j+i]+fj*R[i])^2 ) is minimal. This

** equation gives fj = sum( A[j+i]R[i] ) / sum(R[i]^2).

**

** Next, we compute the relative distance between the original signal and

** the modified signal and minimize that over j:

** vj = sum( (A[j+i]-fj*R[i])^2 ) / sum( A[j+i]^2 ) =>

** vj = ( sum(A[j+i]^2)*sum(R[i]^2) - sum(A[j+i]R[i])^2 ) / sum( A[j+i]^2 )

**

** In the code variables correspond as follows:

** cp1 A

** cp2 R

** len1 N

** len2 n

** aj_m1 A[j-1]

** aj_lm1 A[j+n-1]

** sum_ri_2 sum(R[i]^2)

** sum_aij_2 sum(A[i+j]^2)

** sum_aij_ri sum(A[i+j]R[i])

**

** sum_ri is calculated once, sum_aij_2 is updated each step and sum_aij_ri

** is completely recalculated each step.

*/

static PyObject *

audioop_findfit(PyObject *self, PyObject *args)

{

short *cp1, *cp2;

int len1, len2;

int j, best_j;

double aj_m1, aj_lm1;

double sum_ri_2, sum_aij_2, sum_aij_ri, result, best_result, factor;

/* Passing a short** for an 's' argument is correct only

if the string contents is aligned for interpretation

as short[]. Due to the definition of PyStringObject,

this is currently (Python 2.6) the case. */

if ( !PyArg_ParseTuple(args, "s#s#:findfit",

(char**)&cp1, &len1, (char**)&cp2, &len2) )

return 0;

if ( len1 & 1 || len2 & 1 ) {

PyErr_SetString(AudioopError, "Strings should be even-sized");

return 0;

}

len1 >>= 1;

len2 >>= 1;

if ( len1 < len2 ) {

PyErr_SetString(AudioopError, "First sample should be longer");

return 0;

}

sum_ri_2 = _sum2(cp2, cp2, len2);

sum_aij_2 = _sum2(cp1, cp1, len2);

sum_aij_ri = _sum2(cp1, cp2, len2);

result = (sum_ri_2*sum_aij_2 - sum_aij_ri*sum_aij_ri) / sum_aij_2;

best_result = result;

best_j = 0;

j = 0;

for ( j=1; j<=len1-len2; j++) {

aj_m1 = (double)cp1[j-1];

aj_lm1 = (double)cp1[j+len2-1];

sum_aij_2 = sum_aij_2 + aj_lm1*aj_lm1 - aj_m1*aj_m1;

sum_aij_ri = _sum2(cp1+j, cp2, len2);

result = (sum_ri_2*sum_aij_2 - sum_aij_ri*sum_aij_ri)

/ sum_aij_2;

if ( result < best_result ) {

best_result = result;

best_j = j;

}

}

factor = _sum2(cp1+best_j, cp2, len2) / sum_ri_2;

return Py_BuildValue("(if)", best_j, factor);

}

/*

** findfactor finds a factor f so that the energy in A-fB is minimal.

** See the comment for findfit for details.

*/

static PyObject *

audioop_findfactor(PyObject *self, PyObject *args)

{

short *cp1, *cp2;

int len1, len2;

double sum_ri_2, sum_aij_ri, result;

if ( !PyArg_ParseTuple(args, "s#s#:findfactor",

(char**)&cp1, &len1, (char**)&cp2, &len2) )

return 0;

if ( len1 & 1 || len2 & 1 ) {

PyErr_SetString(AudioopError, "Strings should be even-sized");

return 0;

}

if ( len1 != len2 ) {

PyErr_SetString(AudioopError, "Samples should be same size");

return 0;

}

len2 >>= 1;

sum_ri_2 = _sum2(cp2, cp2, len2);

sum_aij_ri = _sum2(cp1, cp2, len2);

result = sum_aij_ri / sum_ri_2;

return PyFloat_FromDouble(result);

}

/*

** findmax returns the index of the n-sized segment of the input sample

** that contains the most energy.

*/

static PyObject *

audioop_findmax(PyObject *self, PyObject *args)

{

short *cp1;

int len1, len2;

int j, best_j;

double aj_m1, aj_lm1;

double result, best_result;

if ( !PyArg_ParseTuple(args, "s#i:findmax",

(char**)&cp1, &len1, &len2) )

return 0;

if ( len1 & 1 ) {

PyErr_SetString(AudioopError, "Strings should be even-sized");

return 0;

}

len1 >>= 1;

if ( len1 < len2 ) {

PyErr_SetString(AudioopError, "Input sample should be longer");

return 0;

}

result = _sum2(cp1, cp1, len2);

best_result = result;

best_j = 0;

j = 0;

for ( j=1; j<=len1-len2; j++) {

aj_m1 = (double)cp1[j-1];

aj_lm1 = (double)cp1[j+len2-1];

result = result + aj_lm1*aj_lm1 - aj_m1*aj_m1;

if ( result > best_result ) {

best_result = result;

best_j = j;

}

}

return PyInt_FromLong(best_j);

}

static PyObject *

audioop_avgpp(PyObject *self, PyObject *args)

{

signed char *cp;

int len, size, val = 0, prevval = 0, prevextremevalid = 0,

prevextreme = 0;

int i;

double avg = 0.0;

int diff, prevdiff, extremediff, nextreme = 0;

if ( !PyArg_ParseTuple(args, "s#i:avgpp", &cp, &len, &size) )

return 0;

if ( size != 1 && size != 2 && size != 4 ) {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

/* Compute first delta value ahead. Also automatically makes us

** skip the first extreme value

*/

if ( size == 1 ) prevval = (int)*CHARP(cp, 0);

else if ( size == 2 ) prevval = (int)*SHORTP(cp, 0);

else if ( size == 4 ) prevval = (int)*LONGP(cp, 0);

if ( size == 1 ) val = (int)*CHARP(cp, size);

else if ( size == 2 ) val = (int)*SHORTP(cp, size);

else if ( size == 4 ) val = (int)*LONGP(cp, size);

prevdiff = val - prevval;

for ( i=size; i<len; i+= size) {

if ( size == 1 ) val = (int)*CHARP(cp, i);

else if ( size == 2 ) val = (int)*SHORTP(cp, i);

else if ( size == 4 ) val = (int)*LONGP(cp, i);

diff = val - prevval;

if ( diff*prevdiff < 0 ) {

/* Derivative changed sign. Compute difference to last

** extreme value and remember.

*/

if ( prevextremevalid ) {

extremediff = prevval - prevextreme;

if ( extremediff < 0 )

extremediff = -extremediff;

avg += extremediff;

nextreme++;

}

prevextremevalid = 1;

prevextreme = prevval;

}

prevval = val;

if ( diff != 0 )

prevdiff = diff;

}

if ( nextreme == 0 )

val = 0;

else

val = (int)(avg / (double)nextreme);

return PyInt_FromLong(val);

}

static PyObject *

audioop_maxpp(PyObject *self, PyObject *args)

{

signed char *cp;

int len, size, val = 0, prevval = 0, prevextremevalid = 0,

prevextreme = 0;

int i;

int max = 0;

int diff, prevdiff, extremediff;

if ( !PyArg_ParseTuple(args, "s#i:maxpp", &cp, &len, &size) )

return 0;

if ( size != 1 && size != 2 && size != 4 ) {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

/* Compute first delta value ahead. Also automatically makes us

** skip the first extreme value

*/

if ( size == 1 ) prevval = (int)*CHARP(cp, 0);

else if ( size == 2 ) prevval = (int)*SHORTP(cp, 0);

else if ( size == 4 ) prevval = (int)*LONGP(cp, 0);

if ( size == 1 ) val = (int)*CHARP(cp, size);

else if ( size == 2 ) val = (int)*SHORTP(cp, size);

else if ( size == 4 ) val = (int)*LONGP(cp, size);

prevdiff = val - prevval;

for ( i=size; i<len; i+= size) {

if ( size == 1 ) val = (int)*CHARP(cp, i);

else if ( size == 2 ) val = (int)*SHORTP(cp, i);

else if ( size == 4 ) val = (int)*LONGP(cp, i);

diff = val - prevval;

if ( diff*prevdiff < 0 ) {

/* Derivative changed sign. Compute difference to

** last extreme value and remember.

*/

if ( prevextremevalid ) {

extremediff = prevval - prevextreme;

if ( extremediff < 0 )

extremediff = -extremediff;

if ( extremediff > max )

max = extremediff;

}

prevextremevalid = 1;

prevextreme = prevval;

}

prevval = val;

if ( diff != 0 )

prevdiff = diff;

}

return PyInt_FromLong(max);

}

static PyObject *

audioop_cross(PyObject *self, PyObject *args)

{

signed char *cp;

int len, size, val = 0;

int i;

int prevval, ncross;

if ( !PyArg_ParseTuple(args, "s#i:cross", &cp, &len, &size) )

return 0;

if ( size != 1 && size != 2 && size != 4 ) {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

ncross = -1;

prevval = 17; /* Anything <> 0,1 */

for ( i=0; i<len; i+= size) {

if ( size == 1 ) val = ((int)*CHARP(cp, i)) >> 7;

else if ( size == 2 ) val = ((int)*SHORTP(cp, i)) >> 15;

else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 31;

val = val & 1;

if ( val != prevval ) ncross++;

prevval = val;

}

return PyInt_FromLong(ncross);

}

static PyObject *

audioop_mul(PyObject *self, PyObject *args)

{

signed char *cp, *ncp;

int len, size, val = 0;

double factor, fval, maxval;

PyObject *rv;

int i;

if ( !PyArg_ParseTuple(args, "s#id:mul", &cp, &len, &size, &factor ) )

return 0;

if ( size == 1 ) maxval = (double) 0x7f;

else if ( size == 2 ) maxval = (double) 0x7fff;

else if ( size == 4 ) maxval = (double) 0x7fffffff;

else {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

rv = PyBytes_FromStringAndSize(NULL, len);

if ( rv == 0 )

return 0;

ncp = (signed char *)PyBytes_AsString(rv);

for ( i=0; i < len; i += size ) {

if ( size == 1 ) val = (int)*CHARP(cp, i);

else if ( size == 2 ) val = (int)*SHORTP(cp, i);

else if ( size == 4 ) val = (int)*LONGP(cp, i);

fval = (double)val*factor;

if ( fval > maxval ) fval = maxval;

else if ( fval < -maxval ) fval = -maxval;

val = (int)fval;

if ( size == 1 ) *CHARP(ncp, i) = (signed char)val;

else if ( size == 2 ) *SHORTP(ncp, i) = (short)val;

else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)val;

}

return rv;

}

static PyObject *

audioop_tomono(PyObject *self, PyObject *args)

{

signed char *cp, *ncp;

int len, size, val1 = 0, val2 = 0;

double fac1, fac2, fval, maxval;

PyObject *rv;

int i;

if ( !PyArg_ParseTuple(args, "s#idd:tomono",

&cp, &len, &size, &fac1, &fac2 ) )

return 0;

if ( size == 1 ) maxval = (double) 0x7f;

else if ( size == 2 ) maxval = (double) 0x7fff;

else if ( size == 4 ) maxval = (double) 0x7fffffff;

else {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

rv = PyBytes_FromStringAndSize(NULL, len/2);

if ( rv == 0 )

return 0;

ncp = (signed char *)PyBytes_AsString(rv);

for ( i=0; i < len; i += size*2 ) {

if ( size == 1 ) val1 = (int)*CHARP(cp, i);

else if ( size == 2 ) val1 = (int)*SHORTP(cp, i);

else if ( size == 4 ) val1 = (int)*LONGP(cp, i);

if ( size == 1 ) val2 = (int)*CHARP(cp, i+1);

else if ( size == 2 ) val2 = (int)*SHORTP(cp, i+2);

else if ( size == 4 ) val2 = (int)*LONGP(cp, i+4);

fval = (double)val1*fac1 + (double)val2*fac2;

if ( fval > maxval ) fval = maxval;

else if ( fval < -maxval ) fval = -maxval;

val1 = (int)fval;

if ( size == 1 ) *CHARP(ncp, i/2) = (signed char)val1;

else if ( size == 2 ) *SHORTP(ncp, i/2) = (short)val1;

else if ( size == 4 ) *LONGP(ncp, i/2)= (Py_Int32)val1;

}

return rv;

}

static PyObject *

audioop_tostereo(PyObject *self, PyObject *args)

{

signed char *cp, *ncp;

int len, size, val1, val2, val = 0;

double fac1, fac2, fval, maxval;

PyObject *rv;

int i;

if ( !PyArg_ParseTuple(args, "s#idd:tostereo",

&cp, &len, &size, &fac1, &fac2 ) )

return 0;

if ( size == 1 ) maxval = (double) 0x7f;

else if ( size == 2 ) maxval = (double) 0x7fff;

else if ( size == 4 ) maxval = (double) 0x7fffffff;

else {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

rv = PyBytes_FromStringAndSize(NULL, len*2);

if ( rv == 0 )

return 0;

ncp = (signed char *)PyBytes_AsString(rv);

for ( i=0; i < len; i += size ) {

if ( size == 1 ) val = (int)*CHARP(cp, i);

else if ( size == 2 ) val = (int)*SHORTP(cp, i);

else if ( size == 4 ) val = (int)*LONGP(cp, i);

fval = (double)val*fac1;

if ( fval > maxval ) fval = maxval;

else if ( fval < -maxval ) fval = -maxval;

val1 = (int)fval;

fval = (double)val*fac2;

if ( fval > maxval ) fval = maxval;

else if ( fval < -maxval ) fval = -maxval;

val2 = (int)fval;

if ( size == 1 ) *CHARP(ncp, i*2) = (signed char)val1;

else if ( size == 2 ) *SHORTP(ncp, i*2) = (short)val1;

else if ( size == 4 ) *LONGP(ncp, i*2) = (Py_Int32)val1;

if ( size == 1 ) *CHARP(ncp, i*2+1) = (signed char)val2;

else if ( size == 2 ) *SHORTP(ncp, i*2+2) = (short)val2;

else if ( size == 4 ) *LONGP(ncp, i*2+4) = (Py_Int32)val2;

}

return rv;

}

static PyObject *

audioop_add(PyObject *self, PyObject *args)

{

signed char *cp1, *cp2, *ncp;

int len1, len2, size, val1 = 0, val2 = 0, maxval, newval;

PyObject *rv;

int i;

if ( !PyArg_ParseTuple(args, "s#s#i:add",

&cp1, &len1, &cp2, &len2, &size ) )

return 0;

if ( len1 != len2 ) {

PyErr_SetString(AudioopError, "Lengths should be the same");

return 0;

}

if ( size == 1 ) maxval = 0x7f;

else if ( size == 2 ) maxval = 0x7fff;

else if ( size == 4 ) maxval = 0x7fffffff;

else {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

rv = PyBytes_FromStringAndSize(NULL, len1);

if ( rv == 0 )

return 0;

ncp = (signed char *)PyBytes_AsString(rv);

for ( i=0; i < len1; i += size ) {

if ( size == 1 ) val1 = (int)*CHARP(cp1, i);

else if ( size == 2 ) val1 = (int)*SHORTP(cp1, i);

else if ( size == 4 ) val1 = (int)*LONGP(cp1, i);

if ( size == 1 ) val2 = (int)*CHARP(cp2, i);

else if ( size == 2 ) val2 = (int)*SHORTP(cp2, i);

else if ( size == 4 ) val2 = (int)*LONGP(cp2, i);

newval = val1 + val2;

/* truncate in case of overflow */

if (newval > maxval) newval = maxval;

else if (newval < -maxval) newval = -maxval;

else if (size == 4 && (newval^val1) < 0 && (newval^val2) < 0)

newval = val1 > 0 ? maxval : - maxval;

if ( size == 1 ) *CHARP(ncp, i) = (signed char)newval;

else if ( size == 2 ) *SHORTP(ncp, i) = (short)newval;

else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)newval;

}

return rv;

}

static PyObject *

audioop_bias(PyObject *self, PyObject *args)

{

signed char *cp, *ncp;

int len, size, val = 0;

PyObject *rv;

int i;

int bias;

if ( !PyArg_ParseTuple(args, "s#ii:bias",

&cp, &len, &size , &bias) )

return 0;

if ( size != 1 && size != 2 && size != 4) {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

rv = PyBytes_FromStringAndSize(NULL, len);

if ( rv == 0 )

return 0;

ncp = (signed char *)PyBytes_AsString(rv);

for ( i=0; i < len; i += size ) {

if ( size == 1 ) val = (int)*CHARP(cp, i);

else if ( size == 2 ) val = (int)*SHORTP(cp, i);

else if ( size == 4 ) val = (int)*LONGP(cp, i);

if ( size == 1 ) *CHARP(ncp, i) = (signed char)(val+bias);

else if ( size == 2 ) *SHORTP(ncp, i) = (short)(val+bias);

else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)(val+bias);

}

return rv;

}

static PyObject *

audioop_reverse(PyObject *self, PyObject *args)

{

signed char *cp;

unsigned char *ncp;

int len, size, val = 0;

PyObject *rv;

int i, j;

if ( !PyArg_ParseTuple(args, "s#i:reverse",

&cp, &len, &size) )

return 0;

if ( size != 1 && size != 2 && size != 4 ) {

PyErr_SetString(AudioopError, "Size should be 1, 2 or 4");

return 0;

}

rv = PyBytes_FromStringAndSize(NULL, len);

if ( rv == 0 )

return 0;

ncp = (unsigned char *)PyBytes_AsString(rv);

for ( i=0; i < len; i += size ) {

if ( size == 1 ) val = ((int)*CHARP(cp, i)) << 8;

else if ( size == 2 ) val = (int)*SHORTP(cp, i);

else if ( size == 4 ) val = ((int)*LONGP(cp, i)) >> 16;

j = len - i - size;

if ( size == 1 ) *CHARP(ncp, j) = (signed char)(val >> 8);