/* The audioop module uses the code base in g777.c file of the Sox project.

Source: https://sourceforge.net/projects/sox/files/sox/12.17.7/sox-12.17.7.tar.gz

Copyright of g771.c:

* This source code is a product of Sun Microsystems, Inc. and is provided

* for unrestricted use. Users may copy or modify this source code without

* charge.

*

* SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING

* THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR

* PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.

*

* Sun source code is provided with no support and without any obligation on

* the part of Sun Microsystems, Inc. to assist in its use, correction,

* modification or enhancement.

*

* SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE

* INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE

* OR ANY PART THEREOF.

*

* In no event will Sun Microsystems, Inc. be liable for any lost revenue

* or profits or other special, indirect and consequential damages, even if

* Sun has been advised of the possibility of such damages.

*

* Sun Microsystems, Inc.

* 2550 Garcia Avenue

* Mountain View, California 94043 */

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

#define PY_SSIZE_T_CLEAN

#include "Python.h"

static const int maxvals[] = {0, 0x7F, 0x7FFF, 0x7FFFFF, 0x7FFFFFFF};

/* -1 trick is needed on Windows to support -0x80000000 without a warning */

static const int minvals[] = {0, -0x80, -0x8000, -0x800000, -0x7FFFFFFF-1};

static const unsigned int masks[] = {0, 0xFF, 0xFFFF, 0xFFFFFF, 0xFFFFFFFF};

static int

fbound(double val, double minval, double maxval)

{

if (val > maxval) {

val = maxval;

}

else if (val < minval + 1.0) {

val = minval;

}

/* Round towards minus infinity (-inf) */

val = floor(val);

/* Cast double to integer: round towards zero */

return (int)val;

}

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

#define CLIP 32635

#define SIGN_BIT (0x80) /* Sign bit for an 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 const int16_t seg_aend[8] = {

0x1F, 0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF

};

static const int16_t seg_uend[8] = {

0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF

};

static int16_t

search(int16_t val, const int16_t *table, int size)

{

assert(0 <= size);

assert(size < INT16_MAX);

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 const int16_t _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 an 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(int16_t pcm_val) /* 2's complement (14-bit range) */

{

int16_t mask;

int16_t seg;

unsigned char uval;

/* 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 {

assert(seg >= 0);

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

return (uval ^ mask);

}

}

static const int16_t _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 a 13-bit signed integer and encodes it as A-law data

* stored in an 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(int16_t pcm_val) /* 2's complement (13-bit range) */

{

int16_t mask;

int16_t seg;

unsigned char aval;

/* 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 const int indexTable[16] = {

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

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

};

static const 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 GETINTX(T, cp, i) (*(T *)((unsigned char *)(cp) + (i)))

#define SETINTX(T, cp, i, val) do { \

*(T *)((unsigned char *)(cp) + (i)) = (T)(val); \

} while (0)

#define GETINT8(cp, i) GETINTX(signed char, (cp), (i))

#define GETINT16(cp, i) GETINTX(int16_t, (cp), (i))

#define GETINT32(cp, i) GETINTX(int32_t, (cp), (i))

#ifdef WORDS_BIGENDIAN

#define GETINT24(cp, i) ( \

((unsigned char *)(cp) + (i))[2] + \

(((unsigned char *)(cp) + (i))[1] * (1 << 8)) + \

(((signed char *)(cp) + (i))[0] * (1 << 16)) )

#else

#define GETINT24(cp, i) ( \

((unsigned char *)(cp) + (i))[0] + \

(((unsigned char *)(cp) + (i))[1] * (1 << 8)) + \

(((signed char *)(cp) + (i))[2] * (1 << 16)) )

#endif

#define SETINT8(cp, i, val) SETINTX(signed char, (cp), (i), (val))

#define SETINT16(cp, i, val) SETINTX(int16_t, (cp), (i), (val))

#define SETINT32(cp, i, val) SETINTX(int32_t, (cp), (i), (val))

#ifdef WORDS_BIGENDIAN

#define SETINT24(cp, i, val) do { \

((unsigned char *)(cp) + (i))[2] = (int)(val); \

((unsigned char *)(cp) + (i))[1] = (int)(val) >> 8; \

((signed char *)(cp) + (i))[0] = (int)(val) >> 16; \

} while (0)

#else

#define SETINT24(cp, i, val) do { \

((unsigned char *)(cp) + (i))[0] = (int)(val); \

((unsigned char *)(cp) + (i))[1] = (int)(val) >> 8; \

((signed char *)(cp) + (i))[2] = (int)(val) >> 16; \

} while (0)

#endif

#define GETRAWSAMPLE(size, cp, i) ( \

(size == 1) ? (int)GETINT8((cp), (i)) : \

(size == 2) ? (int)GETINT16((cp), (i)) : \

(size == 3) ? (int)GETINT24((cp), (i)) : \

(int)GETINT32((cp), (i)))

#define SETRAWSAMPLE(size, cp, i, val) do { \

if (size == 1) \

SETINT8((cp), (i), (val)); \

else if (size == 2) \

SETINT16((cp), (i), (val)); \

else if (size == 3) \

SETINT24((cp), (i), (val)); \

else \

SETINT32((cp), (i), (val)); \

} while(0)

#define GETSAMPLE32(size, cp, i) ( \

(size == 1) ? (int)GETINT8((cp), (i)) * (1 << 24) : \

(size == 2) ? (int)GETINT16((cp), (i)) * (1 << 16) : \

(size == 3) ? (int)GETINT24((cp), (i)) * (1 << 8) : \

(int)GETINT32((cp), (i)))

#define SETSAMPLE32(size, cp, i, val) do { \

if (size == 1) \

SETINT8((cp), (i), (val) >> 24); \

else if (size == 2) \

SETINT16((cp), (i), (val) >> 16); \

else if (size == 3) \

SETINT24((cp), (i), (val) >> 8); \

else \

SETINT32((cp), (i), (val)); \

} while(0)

static PyModuleDef audioopmodule;

typedef struct {

PyObject *AudioopError;

} audioop_state;

static inline audioop_state *

get_audioop_state(PyObject *module)

{

void *state = PyModule_GetState(module);

assert(state != NULL);

return (audioop_state *)state;

}

static int

audioop_check_size(PyObject *module, int size)

{

if (size < 1 || size > 4) {

PyErr_SetString(get_audioop_state(module)->AudioopError,

"Size should be 1, 2, 3 or 4");

return 0;

}

else

return 1;

}

static int

audioop_check_parameters(PyObject *module, Py_ssize_t len, int size)

{

if (!audioop_check_size(module, size))

return 0;

if (len % size != 0) {

PyErr_SetString(get_audioop_state(module)->AudioopError,

"not a whole number of frames");

return 0;

}

return 1;

}

/*[clinic input]

module audioop

[clinic start generated code]*/

/*[clinic end generated code: output=da39a3ee5e6b4b0d input=8fa8f6611be3591a]*/

/*[clinic input]

audioop.getsample

fragment: Py_buffer

width: int

index: Py_ssize_t

/

Return the value of sample index from the fragment.

[clinic start generated code]*/

static PyObject *

audioop_getsample_impl(PyObject *module, Py_buffer *fragment, int width,

Py_ssize_t index)

/*[clinic end generated code: output=8fe1b1775134f39a input=88edbe2871393549]*/

{

int val;

if (!audioop_check_parameters(module, fragment->len, width))

return NULL;

if (index < 0 || index >= fragment->len/width) {

PyErr_SetString(get_audioop_state(module)->AudioopError,

"Index out of range");

return NULL;

}

val = GETRAWSAMPLE(width, fragment->buf, index*width);

return PyLong_FromLong(val);

}

/*[clinic input]

audioop.max

fragment: Py_buffer

width: int

/

Return the maximum of the absolute value of all samples in a fragment.

[clinic start generated code]*/

static PyObject *

audioop_max_impl(PyObject *module, Py_buffer *fragment, int width)

/*[clinic end generated code: output=e6c5952714f1c3f0 input=32bea5ea0ac8c223]*/

{

Py_ssize_t i;

unsigned int absval, max = 0;

if (!audioop_check_parameters(module, fragment->len, width))

return NULL;

for (i = 0; i < fragment->len; i += width) {

int val = GETRAWSAMPLE(width, fragment->buf, i);

/* Cast to unsigned before negating. Unsigned overflow is well-

defined, but signed overflow is not. */

if (val < 0) absval = (unsigned int)-(int64_t)val;

else absval = val;

if (absval > max) max = absval;

}

return PyLong_FromUnsignedLong(max);

}

/*[clinic input]

audioop.minmax

fragment: Py_buffer

width: int

/

Return the minimum and maximum values of all samples in the sound fragment.

[clinic start generated code]*/

static PyObject *

audioop_minmax_impl(PyObject *module, Py_buffer *fragment, int width)

/*[clinic end generated code: output=473fda66b15c836e input=89848e9b927a0696]*/

{

Py_ssize_t i;

/* -1 trick below is needed on Windows to support -0x80000000 without

a warning */

int min = 0x7fffffff, max = -0x7FFFFFFF-1;

if (!audioop_check_parameters(module, fragment->len, width))

return NULL;

for (i = 0; i < fragment->len; i += width) {

int val = GETRAWSAMPLE(width, fragment->buf, i);

if (val > max) max = val;

if (val < min) min = val;

}

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

}

/*[clinic input]

audioop.avg

fragment: Py_buffer

width: int

/

Return the average over all samples in the fragment.

[clinic start generated code]*/

static PyObject *

audioop_avg_impl(PyObject *module, Py_buffer *fragment, int width)

/*[clinic end generated code: output=4410a4c12c3586e6 input=1114493c7611334d]*/

{

Py_ssize_t i;

int avg;

double sum = 0.0;

if (!audioop_check_parameters(module, fragment->len, width))

return NULL;

for (i = 0; i < fragment->len; i += width)

sum += GETRAWSAMPLE(width, fragment->buf, i);

if (fragment->len == 0)

avg = 0;

else

avg = (int)floor(sum / (double)(fragment->len/width));

return PyLong_FromLong(avg);

}

/*[clinic input]

audioop.rms

fragment: Py_buffer

width: int

/

Return the root-mean-square of the fragment, i.e. sqrt(sum(S_i^2)/n).

[clinic start generated code]*/

static PyObject *

audioop_rms_impl(PyObject *module, Py_buffer *fragment, int width)

/*[clinic end generated code: output=1e7871c826445698 input=4cc57c6c94219d78]*/

{

Py_ssize_t i;

unsigned int res;

double sum_squares = 0.0;

if (!audioop_check_parameters(module, fragment->len, width))

return NULL;

for (i = 0; i < fragment->len; i += width) {

double val = GETRAWSAMPLE(width, fragment->buf, i);

sum_squares += val*val;

}

if (fragment->len == 0)

res = 0;

else

res = (unsigned int)sqrt(sum_squares / (double)(fragment->len/width));

return PyLong_FromUnsignedLong(res);

}

static double _sum2(const int16_t *a, const int16_t *b, Py_ssize_t len)

{

Py_ssize_t 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.

*/

/*[clinic input]

audioop.findfit

fragment: Py_buffer

reference: Py_buffer

/

Try to match reference as well as possible to a portion of fragment.

[clinic start generated code]*/

static PyObject *

audioop_findfit_impl(PyObject *module, Py_buffer *fragment,

Py_buffer *reference)

/*[clinic end generated code: output=5752306d83cbbada input=62c305605e183c9a]*/

{

const int16_t *cp1, *cp2;

Py_ssize_t len1, len2;

Py_ssize_t j, best_j;

double aj_m1, aj_lm1;

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

if (fragment->len & 1 || reference->len & 1) {

PyErr_SetString(get_audioop_state(module)->AudioopError,

"Strings should be even-sized");

return NULL;

}

cp1 = (const int16_t *)fragment->buf;

len1 = fragment->len >> 1;

cp2 = (const int16_t *)reference->buf;

len2 = reference->len >> 1;

if (len1 < len2) {

PyErr_SetString(get_audioop_state(module)->AudioopError,

"First sample should be longer");

return NULL;

}

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;

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("(nf)", best_j, factor);

}

/*

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

** See the comment for findfit for details.

*/

/*[clinic input]

audioop.findfactor

fragment: Py_buffer

reference: Py_buffer

/

Return a factor F such that rms(add(fragment, mul(reference, -F))) is minimal.

[clinic start generated code]*/

static PyObject *

audioop_findfactor_impl(PyObject *module, Py_buffer *fragment,

Py_buffer *reference)

/*[clinic end generated code: output=14ea95652c1afcf8 input=816680301d012b21]*/

{

const int16_t *cp1, *cp2;

Py_ssize_t len;

double sum_ri_2, sum_aij_ri, result;

if (fragment->len & 1 || reference->len & 1) {

PyErr_SetString(get_audioop_state(module)->AudioopError,

"Strings should be even-sized");

return NULL;

}

if (fragment->len != reference->len) {

PyErr_SetString(get_audioop_state(module)->AudioopError,

"Samples should be same size");

return NULL;

}

cp1 = (const int16_t *)fragment->buf;

cp2 = (const int16_t *)reference->buf;

len = fragment->len >> 1;

sum_ri_2 = _sum2(cp2, cp2, len);

sum_aij_ri = _sum2(cp1, cp2, len);

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.

*/

/*[clinic input]

audioop.findmax

fragment: Py_buffer

length: Py_ssize_t

/

Search fragment for a slice of specified number of samples with maximum energy.

[clinic start generated code]*/

static PyObject *

audioop_findmax_impl(PyObject *module, Py_buffer *fragment,

Py_ssize_t length)

/*[clinic end generated code: output=f008128233523040 input=2f304801ed42383c]*/

{

const int16_t *cp1;

Py_ssize_t len1;

Py_ssize_t j, best_j;

double aj_m1, aj_lm1;

double result, best_result;

if (fragment->len & 1) {

PyErr_SetString(get_audioop_state(module)->AudioopError,

"Strings should be even-sized");

return NULL;

}

cp1 = (const int16_t *)fragment->buf;

len1 = fragment->len >> 1;

if (length < 0 || len1 < length) {

PyErr_SetString(get_audioop_state(module)->AudioopError,

"Input sample should be longer");

return NULL;

}

result = _sum2(cp1, cp1, length);

best_result = result;

best_j = 0;

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

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

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

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

if ( result > best_result ) {

best_result = result;

best_j = j;

}

}

return PyLong_FromSsize_t(best_j);

}

/*[clinic input]

audioop.avgpp

fragment: Py_buffer

width: int

/

Return the average peak-peak value over all samples in the fragment.

[clinic start generated code]*/

static PyObject *

audioop_avgpp_impl(PyObject *module, Py_buffer *fragment, int width)

/*[clinic end generated code: output=269596b0d5ae0b2b input=0b3cceeae420a7d9]*/

{

Py_ssize_t i;

int prevval, prevextremevalid = 0, prevextreme = 0;

double sum = 0.0;

unsigned int avg;

int diff, prevdiff, nextreme = 0;

if (!audioop_check_parameters(module, fragment->len, width))

return NULL;

if (fragment->len <= width)

return PyLong_FromLong(0);

prevval = GETRAWSAMPLE(width, fragment->buf, 0);

prevdiff = 17; /* Anything != 0, 1 */

for (i = width; i < fragment->len; i += width) {

int val = GETRAWSAMPLE(width, fragment->buf, i);

if (val != prevval) {

diff = val < prevval;

if (prevdiff == !diff) {

/* Derivative changed sign. Compute difference to last

** extreme value and remember.

*/

if (prevextremevalid) {

if (prevval < prevextreme)

sum += (double)((unsigned int)prevextreme -

(unsigned int)prevval);

else

sum += (double)((unsigned int)prevval -

(unsigned int)prevextreme);

nextreme++;

}

prevextremevalid = 1;

prevextreme = prevval;

}

prevval = val;

prevdiff = diff;

}

}

if ( nextreme == 0 )

avg = 0;

else

avg = (unsigned int)(sum / (double)nextreme);

return PyLong_FromUnsignedLong(avg);

}

/*[clinic input]

audioop.maxpp

fragment: Py_buffer

width: int

/

Return the maximum peak-peak value in the sound fragment.

[clinic start generated code]*/

static PyObject *

audioop_maxpp_impl(PyObject *module, Py_buffer *fragment, int width)

/*[clinic end generated code: output=5b918ed5dbbdb978 input=671a13e1518f80a1]*/

{

Py_ssize_t i;

int prevval, prevextremevalid = 0, prevextreme = 0;

unsigned int max = 0, extremediff;

int diff, prevdiff;

if (!audioop_check_parameters(module, fragment->len, width))

return NULL;

if (fragment->len <= width)

return PyLong_FromLong(0);

prevval = GETRAWSAMPLE(width, fragment->buf, 0);

prevdiff = 17; /* Anything != 0, 1 */

for (i = width; i < fragment->len; i += width) {

int val = GETRAWSAMPLE(width, fragment->buf, i);

if (val != prevval) {

diff = val < prevval;

if (prevdiff == !diff) {

/* Derivative changed sign. Compute difference to

** last extreme value and remember.

*/

if (prevextremevalid) {

if (prevval < prevextreme)

extremediff = (unsigned int)prevextreme -

(unsigned int)prevval;

else

extremediff = (unsigned int)prevval -

(unsigned int)prevextreme;

if ( extremediff > max )

max = extremediff;

}

prevextremevalid = 1;

prevextreme = prevval;

}

prevval = val;

prevdiff = diff;

}

}

return PyLong_FromUnsignedLong(max);

}

/*[clinic input]

audioop.cross

fragment: Py_buffer

width: int

/

Return the number of zero crossings in the fragment passed as an argument.

[clinic start generated code]*/

static PyObject *

audioop_cross_impl(PyObject *module, Py_buffer *fragment, int width)

/*[clinic end generated code: output=5938dcdd74a1f431 input=b1b3f15b83f6b41a]*/

{

Py_ssize_t i;

int prevval;

Py_ssize_t ncross;

if (!audioop_check_parameters(module, fragment->len, width))

return NULL;

ncross = -1;

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

for (i = 0; i < fragment->len; i += width) {

int val = GETRAWSAMPLE(width, fragment->buf, i) < 0;

if (val != prevval) ncross++;

prevval = val;

}

return PyLong_FromSsize_t(ncross);

}

/*[clinic input]

audioop.mul

fragment: Py_buffer

width: int

factor: double

/

Return a fragment that has all samples in the original fragment multiplied by the floating-point value factor.

[clinic start generated code]*/

static PyObject *

audioop_mul_impl(PyObject *module, Py_buffer *fragment, int width,

double factor)

/*[clinic end generated code: output=6cd48fe796da0ea4 input=c726667baa157d3c]*/

{

signed char *ncp;

Py_ssize_t i;

double maxval, minval;

PyObject *rv;

if (!audioop_check_parameters(module, fragment->len, width))

return NULL;

maxval = (double) maxvals[width];

minval = (double) minvals[width];

rv = PyBytes_FromStringAndSize(NULL, fragment->len);

if (rv == NULL)

return NULL;

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

for (i = 0; i < fragment->len; i += width) {

double val = GETRAWSAMPLE(width, fragment->buf, i);

int ival = fbound(val * factor, minval, maxval);

SETRAWSAMPLE(width, ncp, i, ival);

}

return rv;

}

/*[clinic input]

audioop.tomono

fragment: Py_buffer

width: int

lfactor: double

rfactor: double

/

Convert a stereo fragment to a mono fragment.

[clinic start generated code]*/

static PyObject *

audioop_tomono_impl(PyObject *module, Py_buffer *fragment, int width,

double lfactor, double rfactor)

/*[clinic end generated code: output=235c8277216d4e4e input=c4ec949b3f4dddfa]*/

{

signed char *cp, *ncp;

Py_ssize_t len, i;

double maxval, minval;

PyObject *rv;

cp = fragment->buf;

len = fragment->len;

if (!audioop_check_parameters(module, len, width))

return NULL;

if (((len / width) & 1) != 0) {

PyErr_SetString(get_audioop_state(module)->AudioopError,

"not a whole number of frames");

return NULL;

}