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annotate libgsmfr2/add.c @ 543:53d3f48af107

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libgsmefr is now at version 1.2.0
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 29 Sep 2024 02:41:28 +0000
parents a7b593e68ac3
children
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8b21a6b7a3bf libgsmfr2: beginning to integrate TU-Berlin code guts
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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
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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
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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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114 word gsm_norm (longword a)
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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 }