FreeCalypso > hg > gsm-codec-lib
annotate dev/s2u-regen-plus4.c @ 452:6e595f7d40e2
CHANGES: document changes for the upcoming release
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Fri, 10 May 2024 03:45:47 +0000 |
parents | 67d60915fbbe |
children |
rev | line source |
---|---|
222
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
1 /* |
228
67d60915fbbe
dev: new program s2u-regen-plus4
Mychaela Falconia <falcon@freecalypso.org>
parents:
227
diff
changeset
|
2 * This program is a companion to s2u-regen.c: it computes a mu-law encoding |
67d60915fbbe
dev: new program s2u-regen-plus4
Mychaela Falconia <falcon@freecalypso.org>
parents:
227
diff
changeset
|
3 * table with 13-bit input just like s2u-regen, but computes it as if the |
67d60915fbbe
dev: new program s2u-regen-plus4
Mychaela Falconia <falcon@freecalypso.org>
parents:
227
diff
changeset
|
4 * lsb following the 13-bit part is always 1 rather than always 0. The |
67d60915fbbe
dev: new program s2u-regen-plus4
Mychaela Falconia <falcon@freecalypso.org>
parents:
227
diff
changeset
|
5 * purpose of this program is to illustrate the effect of that lsb on the |
67d60915fbbe
dev: new program s2u-regen-plus4
Mychaela Falconia <falcon@freecalypso.org>
parents:
227
diff
changeset
|
6 * mu-law output. |
222
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
7 */ |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
8 |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
9 #include <stdio.h> |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
10 #include <stdlib.h> |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
11 |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
12 static unsigned |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
13 ulaw_compress(input) |
222
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
14 unsigned input; |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
15 { |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
16 short i; /* aux.var. */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
17 short absno; /* absolute value of linear (input) sample */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
18 short segno; /* segment (Table 2/G711, column 1) */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
19 short low_nibble; /* low nibble of log companded sample */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
20 short high_nibble; /* high nibble of log companded sample */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
21 unsigned output; |
222
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
22 |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
23 /* -------------------------------------------------------------------- */ |
227
a5200ad12d58
dev/s2u-regen.c: new approach
Mychaela Falconia <falcon@freecalypso.org>
parents:
226
diff
changeset
|
24 /* Input is 14-bit right-justified in this version */ |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
25 /* Compute absolute value; adjust for easy processing */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
26 /* -------------------------------------------------------------------- */ |
227
a5200ad12d58
dev/s2u-regen.c: new approach
Mychaela Falconia <falcon@freecalypso.org>
parents:
226
diff
changeset
|
27 absno = input >= 0x2000 /* compute 1's complement in case of */ |
a5200ad12d58
dev/s2u-regen.c: new approach
Mychaela Falconia <falcon@freecalypso.org>
parents:
226
diff
changeset
|
28 ? (~input & 0x1FFF) + 33 /* negative samples */ |
a5200ad12d58
dev/s2u-regen.c: new approach
Mychaela Falconia <falcon@freecalypso.org>
parents:
226
diff
changeset
|
29 : input + 33; /* NB: 33 is the difference value */ |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
30 /* between the thresholds for */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
31 /* A-law and u-law. */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
32 if (absno > (0x1FFF)) /* limitation to "absno" < 8192 */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
33 absno = (0x1FFF); |
222
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
34 |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
35 /* Determination of sample's segment */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
36 i = absno >> 6; |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
37 segno = 1; |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
38 while (i != 0) { |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
39 segno++; |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
40 i >>= 1; |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
41 } |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
42 |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
43 /* Mounting the high-nibble of the log-PCM sample */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
44 high_nibble = (0x0008) - segno; |
222
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
45 |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
46 /* Mounting the low-nibble of the log PCM sample */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
47 low_nibble = (absno >> segno) /* right shift of mantissa and */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
48 &(0x000F); /* masking away leading '1' */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
49 low_nibble = (0x000F) - low_nibble; |
222
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
50 |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
51 /* Joining the high-nibble and the low-nibble of the log PCM sample */ |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
52 output = (high_nibble << 4) | low_nibble; |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
53 |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
54 /* Add sign bit */ |
227
a5200ad12d58
dev/s2u-regen.c: new approach
Mychaela Falconia <falcon@freecalypso.org>
parents:
226
diff
changeset
|
55 if (input < 0x2000) |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
56 output = output | (0x0080); |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
57 |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
58 return output; |
222
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
59 } |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
60 |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
61 main(argc, argv) |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
62 char **argv; |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
63 { |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
64 unsigned input, output; |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
65 |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
66 for (input = 0; input < 8192; input++) { |
228
67d60915fbbe
dev: new program s2u-regen-plus4
Mychaela Falconia <falcon@freecalypso.org>
parents:
227
diff
changeset
|
67 output = ulaw_compress((input << 1) + 1); |
226
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
68 printf("%04o,", output); |
84d22eb72196
dev: new program s2u-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
223
diff
changeset
|
69 if ((input % 15) == 14 || input == 8191) |
222
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
70 putchar('\n'); |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
71 } |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
72 exit(0); |
842136bbd0da
dev: new program s2a-regen
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff
changeset
|
73 } |