Author: Amaury Forgeot d'Arc <amaur...@gmail.com>
Branch: py3.3
Changeset: r75175:96b5281e7963
Date: 2014-12-30 23:57 +0100
http://bitbucket.org/pypy/pypy/changeset/96b5281e7963/

Log:    Full implementation of the audioop module! Reuse large parts of C
        code from CPython, and use cffi to access it.

diff --git a/lib-python/3/test/test_audioop.py 
b/lib-python/3/test/test_audioop.py
--- a/lib-python/3/test/test_audioop.py
+++ b/lib-python/3/test/test_audioop.py
@@ -1,7 +1,6 @@
 import audioop
 import sys
 import unittest
-from test.support import run_unittest, impl_detail
 
 def pack(width, data):
     return b''.join(v.to_bytes(width, sys.byteorder, signed=True) for v in 
data)
@@ -171,7 +170,6 @@
         self.assertEqual(audioop.lin2lin(datas[4], 4, 2),
             packs[2](0, 0x1234, 0x4567, -0x4568, 0x7fff, -0x8000, -1))
 
-    @impl_detail(pypy=False)
     def test_adpcm2lin(self):
         self.assertEqual(audioop.adpcm2lin(b'\x07\x7f\x7f', 1, None),
                          (b'\x00\x00\x00\xff\x00\xff', (-179, 40)))
@@ -186,7 +184,6 @@
             self.assertEqual(audioop.adpcm2lin(b'\0' * 5, w, None),
                              (b'\0' * w * 10, (0, 0)))
 
-    @impl_detail(pypy=False)
     def test_lin2adpcm(self):
         self.assertEqual(audioop.lin2adpcm(datas[1], 1, None),
                          (b'\x07\x7f\x7f', (-221, 39)))
@@ -200,7 +197,6 @@
             self.assertEqual(audioop.lin2adpcm(b'\0' * w * 10, w, None),
                              (b'\0' * 5, (0, 0)))
 
-    @impl_detail(pypy=False)
     def test_lin2alaw(self):
         self.assertEqual(audioop.lin2alaw(datas[1], 1),
                          b'\xd5\x87\xa4\x24\xaa\x2a\x5a')
@@ -209,7 +205,6 @@
         self.assertEqual(audioop.lin2alaw(datas[4], 4),
                          b'\xd5\x87\xa4\x24\xaa\x2a\x55')
 
-    @impl_detail(pypy=False)
     def test_alaw2lin(self):
         encoded = b'\x00\x03\x24\x2a\x51\x54\x55\x58\x6b\x71\x7f'\
                   b'\x80\x83\xa4\xaa\xd1\xd4\xd5\xd8\xeb\xf1\xff'
@@ -224,7 +219,6 @@
             decoded = audioop.alaw2lin(encoded, w)
             self.assertEqual(audioop.lin2alaw(decoded, w), encoded)
 
-    @impl_detail(pypy=False)
     def test_lin2ulaw(self):
         self.assertEqual(audioop.lin2ulaw(datas[1], 1),
                          b'\xff\xad\x8e\x0e\x80\x00\x67')
@@ -233,7 +227,6 @@
         self.assertEqual(audioop.lin2ulaw(datas[4], 4),
                          b'\xff\xad\x8e\x0e\x80\x00\x7e')
 
-    @impl_detail(pypy=False)
     def test_ulaw2lin(self):
         encoded = b'\x00\x0e\x28\x3f\x57\x6a\x76\x7c\x7e\x7f'\
                   b'\x80\x8e\xa8\xbf\xd7\xea\xf6\xfc\xfe\xff'
@@ -348,7 +341,6 @@
         self.assertRaises(audioop.error,
             audioop.findmax, bytes(range(256)), -2392392)
 
-    @impl_detail(pypy=False)
     def test_issue7673(self):
         state = None
         for data, size in INVALID_DATA:
@@ -373,7 +365,6 @@
             self.assertRaises(audioop.error, audioop.lin2alaw, data, size)
             self.assertRaises(audioop.error, audioop.lin2adpcm, data, size, 
state)
 
-    @impl_detail(pypy=False)
     def test_wrongsize(self):
         data = b'abcdefgh'
         state = None
diff --git a/lib_pypy/audioop.py b/lib_pypy/audioop.py
--- a/lib_pypy/audioop.py
+++ b/lib_pypy/audioop.py
@@ -527,25 +527,524 @@
                 d -= inrate
 
 
+from cffi import FFI
+ffi = FFI()
+ffi.cdef("""
+typedef short PyInt16;
+
+/* 2's complement (14-bit range) */
+unsigned char
+st_14linear2ulaw(PyInt16 pcm_val);
+PyInt16 st_ulaw2linear16(unsigned char);
+
+/* 2's complement (13-bit range) */
+unsigned char
+st_linear2alaw(PyInt16 pcm_val);
+PyInt16 st_alaw2linear16(unsigned char);
+
+
+void lin2adcpm(unsigned char* rv, unsigned char* cp, size_t len,
+               size_t size, int* state);
+void adcpm2lin(unsigned char* rv, unsigned char* cp, size_t len,
+               size_t size, int* state);
+""")
+
+# This code is directly copied from CPython file: Modules/audioop.c
+_AUDIOOP_C_MODULE = """
+typedef short PyInt16;
+typedef int Py_Int32;
+
+/* 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.
+ * b...@cpk.auc.dk
+ *
+ */
+#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))
+"""
+
+lib = ffi.verify(_AUDIOOP_C_MODULE + """
+void lin2adcpm(unsigned char* ncp, unsigned char* cp, size_t len,
+               size_t size, int* state)
+{
+    int step, outputbuffer = 0, bufferstep;
+    int val = 0;
+    int diff, vpdiff, sign, delta;
+    size_t i;
+    int valpred = state[0];
+    int index = state[1];
+
+    step = stepsizeTable[index];
+    bufferstep = 1;
+
+    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;
+
+        /* Step 1 - compute difference with previous value */
+        diff = val - valpred;
+        sign = (diff < 0) ? 8 : 0;
+        if ( sign ) diff = (-diff);
+
+        /* Step 2 - Divide and clamp */
+        /* Note:
+        ** This code *approximately* computes:
+        **    delta = diff*4/step;
+        **    vpdiff = (delta+0.5)*step/4;
+        ** but in shift step bits are dropped. The net result of this
+        ** is that even if you have fast mul/div hardware you cannot
+        ** put it to good use since the fixup would be too expensive.
+        */
+        delta = 0;
+        vpdiff = (step >> 3);
+
+        if ( diff >= step ) {
+            delta = 4;
+            diff -= step;
+            vpdiff += step;
+        }
+        step >>= 1;
+        if ( diff >= step  ) {
+            delta |= 2;
+            diff -= step;
+            vpdiff += step;
+        }
+        step >>= 1;
+        if ( diff >= step ) {
+            delta |= 1;
+            vpdiff += step;
+        }
+
+        /* Step 3 - Update previous value */
+        if ( sign )
+            valpred -= vpdiff;
+        else
+            valpred += vpdiff;
+
+        /* Step 4 - Clamp previous value to 16 bits */
+        if ( valpred > 32767 )
+            valpred = 32767;
+        else if ( valpred < -32768 )
+            valpred = -32768;
+
+        /* Step 5 - Assemble value, update index and step values */
+        delta |= sign;
+
+        index += indexTable[delta];
+        if ( index < 0 ) index = 0;
+        if ( index > 88 ) index = 88;
+        step = stepsizeTable[index];
+
+        /* Step 6 - Output value */
+        if ( bufferstep ) {
+            outputbuffer = (delta << 4) & 0xf0;
+        } else {
+            *ncp++ = (delta & 0x0f) | outputbuffer;
+        }
+        bufferstep = !bufferstep;
+    }
+    state[0] = valpred;
+    state[1] = index;
+}
+
+
+void adcpm2lin(unsigned char* ncp, unsigned char* cp, size_t len,
+               size_t size, int* state)
+{
+    int step, inputbuffer = 0, bufferstep;
+    int val = 0;
+    int diff, vpdiff, sign, delta;
+    size_t i;
+    int valpred = state[0];
+    int index = state[1];
+
+    step = stepsizeTable[index];
+    bufferstep = 0;
+
+    for ( i=0; i < len*size*2; i += size ) {
+        /* Step 1 - get the delta value and compute next index */
+        if ( bufferstep ) {
+            delta = inputbuffer & 0xf;
+        } else {
+            inputbuffer = *cp++;
+            delta = (inputbuffer >> 4) & 0xf;
+        }
+
+        bufferstep = !bufferstep;
+
+        /* Step 2 - Find new index value (for later) */
+        index += indexTable[delta];
+        if ( index < 0 ) index = 0;
+        if ( index > 88 ) index = 88;
+
+        /* Step 3 - Separate sign and magnitude */
+        sign = delta & 8;
+        delta = delta & 7;
+
+        /* Step 4 - Compute difference and new predicted value */
+        /*
+        ** Computes 'vpdiff = (delta+0.5)*step/4', but see comment
+        ** in adpcm_coder.
+        */
+        vpdiff = step >> 3;
+        if ( delta & 4 ) vpdiff += step;
+        if ( delta & 2 ) vpdiff += step>>1;
+        if ( delta & 1 ) vpdiff += step>>2;
+
+        if ( sign )
+            valpred -= vpdiff;
+        else
+            valpred += vpdiff;
+
+        /* Step 5 - clamp output value */
+        if ( valpred > 32767 )
+            valpred = 32767;
+        else if ( valpred < -32768 )
+            valpred = -32768;
+
+        /* Step 6 - Update step value */
+        step = stepsizeTable[index];
+
+        /* Step 6 - Output value */
+        if ( size == 1 ) *CHARP(ncp, i) = (signed char)(valpred >> 8);
+        else if ( size == 2 ) *SHORTP(ncp, i) = (short)(valpred);
+        else if ( size == 4 ) *LONGP(ncp, i) = (Py_Int32)(valpred<<16);
+    }
+    state[0] = valpred;
+    state[1] = index;
+}
+""")
+
+def _get_lin_samples(cp, size):
+    for sample in _get_samples(cp, size):
+        if size == 1:
+            yield sample << 8
+        elif size == 2:
+            yield sample
+        elif size == 4:
+            yield sample >> 16
+
+def _put_lin_sample(result, size, i, sample):
+    if size == 1:
+        sample >>= 8
+    elif size == 2:
+        pass
+    elif size == 4:
+        sample <<= 16
+    _put_sample(result, size, i, sample)
+
 def lin2ulaw(cp, size):
-    raise NotImplementedError()
+    _check_params(len(cp), size)
+    rv = ffi.new("unsigned char[]", _sample_count(cp, size))
+    for i, sample in enumerate(_get_lin_samples(cp, size)):
+        rv[i] = lib.st_14linear2ulaw(sample)
+    return ffi.buffer(rv)[:]
 
 
 def ulaw2lin(cp, size):
-    raise NotImplementedError()
+    _check_size(size)
+    rv = ffi.new("unsigned char[]", len(cp) * size)
+    result = ffi.buffer(rv)
+    for i, value in enumerate(cp):
+        sample = lib.st_ulaw2linear16(value)
+        _put_lin_sample(result, size, i, sample)
+    return result[:]
 
 
 def lin2alaw(cp, size):
-    raise NotImplementedError()
+    _check_params(len(cp), size)
+    rv = ffi.new("unsigned char[]", _sample_count(cp, size))
+    for i, sample in enumerate(_get_lin_samples(cp, size)):
+        rv[i] = lib.st_linear2alaw(sample)
+    return ffi.buffer(rv)[:]
 
 
 def alaw2lin(cp, size):
-    raise NotImplementedError()
+    _check_size(size)
+    rv = ffi.new("unsigned char[]", len(cp) * size)
+    result = ffi.buffer(rv)
+    for i, value in enumerate(cp):
+        sample = lib.st_alaw2linear16(value)
+        _put_lin_sample(result, size, i, sample)
+    return result[:]
 
 
 def lin2adpcm(cp, size, state):
-    raise NotImplementedError()
+    _check_params(len(cp), size)
+    if state is None:
+        state = (0, 0)
+    rv = ffi.new("unsigned char[]", len(cp) // size // 2)
+    state_ptr = ffi.new("int[]", state)
+    lib.lin2adcpm(rv, cp, len(cp), size, state_ptr)
+    return ffi.buffer(rv)[:], tuple(state_ptr)
 
 
 def adpcm2lin(cp, size, state):
-    raise NotImplementedError()
+    _check_size(size)
+    if state is None:
+        state = (0, 0)
+    rv = ffi.new("unsigned char[]", len(cp) * size * 2)
+    state_ptr = ffi.new("int[]", state)
+    lib.adcpm2lin(rv, cp, len(cp), size, state_ptr)
+    return ffi.buffer(rv)[:], tuple(state_ptr)
+
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