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annotate libgsmfr2/add.c @ 282:9ee8ad3d4d30

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frtest: rm gsmfr-hand-test and gsmfr-max-out utils These hack programs were never properly documented and were written only as part of a debug chase, in pursuit of a bug that ultimately turned out to be in our then-hacky patch to osmo-bts-sysmo, before beginning of proper patches in Osmocom. These hack programs need to be dropped from the present sw package because they depend on old libgsm, and we are eliminating that dependency.
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 14 Apr 2024 05:44:47 +0000
parents a7b593e68ac3
children
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1 /*
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2 * This C source file has been adapted from TU-Berlin libgsm source,
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3 * original notice follows:
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4 *
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5 * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
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6 * Universitaet Berlin. See the accompanying file "COPYRIGHT" for
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
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7 * details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
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8 */
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9
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10 #include <stdint.h>
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11 #include <assert.h>
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12 #include "tw_gsmfr.h"
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13 #include "typedef.h"
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14 #include "ed_state.h"
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15 #include "ed_internal.h"
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16
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17 #define saturate(x) \
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18 ((x) < MIN_WORD ? MIN_WORD : (x) > MAX_WORD ? MAX_WORD: (x))
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19
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
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20 word gsm_add (word a, word b)
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21 {
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22 longword sum = (longword)a + (longword)b;
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23 return saturate(sum);
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24 }
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25
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26 word gsm_sub (word a, word b)
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27 {
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28 longword diff = (longword)a - (longword)b;
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29 return saturate(diff);
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30 }
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31
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32 word gsm_mult (word a, word b)
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33 {
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34 if (a == MIN_WORD && b == MIN_WORD) return MAX_WORD;
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35 else return SASR( (longword)a * (longword)b, 15 );
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36 }
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37
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38 word gsm_mult_r (word a, word b)
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39 {
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40 if (b == MIN_WORD && a == MIN_WORD) return MAX_WORD;
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41 else {
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42 longword prod = (longword)a * (longword)b + 16384;
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43 prod >>= 15;
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44 return prod & 0xFFFF;
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45 }
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46 }
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47
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48 word gsm_abs (word a)
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49 {
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50 return a < 0 ? (a == MIN_WORD ? MAX_WORD : -a) : a;
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51 }
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52
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53 longword gsm_L_mult (word a, word b)
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54 {
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55 assert( a != MIN_WORD || b != MIN_WORD );
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56 return ((longword)a * (longword)b) << 1;
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57 }
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58
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59 longword gsm_L_add (longword a, longword b)
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60 {
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61 if (a < 0) {
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62 if (b >= 0) return a + b;
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63 else {
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64 ulongword A = (ulongword)-(a + 1) + (ulongword)-(b + 1);
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65 return A >= MAX_LONGWORD ? MIN_LONGWORD :-(longword)A-2;
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66 }
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67 }
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68 else if (b <= 0) return a + b;
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69 else {
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70 ulongword A = (ulongword)a + (ulongword)b;
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71 return A > MAX_LONGWORD ? MAX_LONGWORD : A;
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72 }
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73 }
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74
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75 longword gsm_L_sub (longword a, longword b)
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76 {
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77 if (a >= 0) {
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78 if (b >= 0) return a - b;
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79 else {
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80 /* a>=0, b<0 */
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81
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82 ulongword A = (ulongword)a + -(b + 1);
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83 return A >= MAX_LONGWORD ? MAX_LONGWORD : (A + 1);
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84 }
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85 }
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86 else if (b <= 0) return a - b;
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87 else {
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88 /* a<0, b>0 */
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89
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90 ulongword A = (ulongword)-(a + 1) + b;
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91 return A >= MAX_LONGWORD ? MIN_LONGWORD : -(longword)A - 1;
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92 }
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93 }
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94
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95 static unsigned char const bitoff[ 256 ] = {
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96 8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
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97 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
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98 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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99 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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100 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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101 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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102 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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103 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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104 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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105 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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106 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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107 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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108 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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109 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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110 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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111 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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112 };
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113
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Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
114 word gsm_norm (longword a)
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
115 /*
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
116 * the number of left shifts needed to normalize the 32 bit
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
117 * variable L_var1 for positive values on the interval
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
118 *
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
119 * with minimum of
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
120 * minimum of 1073741824 (01000000000000000000000000000000) and
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
121 * maximum of 2147483647 (01111111111111111111111111111111)
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
122 *
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
123 *
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
124 * and for negative values on the interval with
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
125 * minimum of -2147483648 (-10000000000000000000000000000000) and
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
126 * maximum of -1073741824 ( -1000000000000000000000000000000).
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
127 *
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
128 * in order to normalize the result, the following
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
129 * operation must be done: L_norm_var1 = L_var1 << norm( L_var1 );
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
130 *
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
131 * (That's 'ffs', only from the left, not the right..)
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
132 */
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
133 {
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
134 assert(a != 0);
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
135
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
136 if (a < 0) {
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
137 if (a <= -1073741824) return 0;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
138 a = ~a;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
139 }
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
140
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
141 return a & 0xffff0000
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
142 ? ( a & 0xff000000
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
143 ? -1 + bitoff[ 0xFF & (a >> 24) ]
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
144 : 7 + bitoff[ 0xFF & (a >> 16) ] )
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
145 : ( a & 0xff00
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
146 ? 15 + bitoff[ 0xFF & (a >> 8) ]
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
147 : 23 + bitoff[ 0xFF & a ] );
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
148 }
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
149
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
150 longword gsm_L_asl (longword a, int n)
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
151 {
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
152 if (n >= 32) return 0;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
153 if (n <= -32) return -(a < 0);
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
154 if (n < 0) return gsm_L_asr(a, -n);
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
155 return a << n;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
156 }
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
157
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
158 word gsm_asl (word a, int n)
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
159 {
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
160 if (n >= 16) return 0;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
161 if (n <= -16) return -(a < 0);
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
162 if (n < 0) return gsm_asr(a, -n);
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
163 return a << n;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
164 }
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
165
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
166 longword gsm_L_asr (longword a, int n)
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
167 {
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
168 if (n >= 32) return -(a < 0);
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
169 if (n <= -32) return 0;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
170 if (n < 0) return a << -n;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
171
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
172 # ifdef SASR
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
173 return a >> n;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
174 # else
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
175 if (a >= 0) return a >> n;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
176 else return -(longword)( -(ulongword)a >> n );
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
177 # endif
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
178 }
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
179
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
180 word gsm_asr (word a, int n)
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
181 {
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
182 if (n >= 16) return -(a < 0);
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
183 if (n <= -16) return 0;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
184 if (n < 0) return a << -n;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
185
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
186 # ifdef SASR
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
187 return a >> n;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
188 # else
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
189 if (a >= 0) return a >> n;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
190 else return -(word)( -(uword)a >> n );
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
191 # endif
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
192 }
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
193
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
194 /*
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
195 * (From p. 46, end of section 4.2.5)
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
196 *
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
197 * NOTE: The following lines gives [sic] one correct implementation
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
198 * of the div(num, denum) arithmetic operation. Compute div
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
199 * which is the integer division of num by denum: with denum
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
200 * >= num > 0
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
201 */
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
202
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
203 word gsm_div (word num, word denum)
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
204 {
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
205 longword L_num = num;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
206 longword L_denum = denum;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
207 word div = 0;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
208 int k = 15;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
209
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
210 /* The parameter num sometimes becomes zero.
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
211 * Although this is explicitly guarded against in 4.2.5,
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
212 * we assume that the result should then be zero as well.
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
213 */
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
214
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
215 /* assert(num != 0); */
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
216
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
217 assert(num >= 0 && denum >= num);
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
218 if (num == 0)
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
219 return 0;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
220
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
221 while (k--) {
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
222 div <<= 1;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
223 L_num <<= 1;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
224
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
225 if (L_num >= L_denum) {
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
226 L_num -= L_denum;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
227 div++;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
228 }
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
229 }
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
230
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
231 return div;
8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
232 }