1 | /* crypto/bn/bn_shift.c */
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2 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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3 | * All rights reserved.
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4 | *
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5 | * This package is an SSL implementation written
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6 | * by Eric Young (eay@cryptsoft.com).
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7 | * The implementation was written so as to conform with Netscapes SSL.
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8 | *
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9 | * This library is free for commercial and non-commercial use as long as
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10 | * the following conditions are aheared to. The following conditions
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11 | * apply to all code found in this distribution, be it the RC4, RSA,
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12 | * lhash, DES, etc., code; not just the SSL code. The SSL documentation
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13 | * included with this distribution is covered by the same copyright terms
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14 | * except that the holder is Tim Hudson (tjh@cryptsoft.com).
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15 | *
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16 | * Copyright remains Eric Young's, and as such any Copyright notices in
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17 | * the code are not to be removed.
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18 | * If this package is used in a product, Eric Young should be given attribution
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19 | * as the author of the parts of the library used.
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20 | * This can be in the form of a textual message at program startup or
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21 | * in documentation (online or textual) provided with the package.
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22 | *
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23 | * Redistribution and use in source and binary forms, with or without
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24 | * modification, are permitted provided that the following conditions
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25 | * are met:
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26 | * 1. Redistributions of source code must retain the copyright
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27 | * notice, this list of conditions and the following disclaimer.
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28 | * 2. Redistributions in binary form must reproduce the above copyright
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29 | * notice, this list of conditions and the following disclaimer in the
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30 | * documentation and/or other materials provided with the distribution.
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31 | * 3. All advertising materials mentioning features or use of this software
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32 | * must display the following acknowledgement:
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33 | * "This product includes cryptographic software written by
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34 | * Eric Young (eay@cryptsoft.com)"
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35 | * The word 'cryptographic' can be left out if the rouines from the library
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36 | * being used are not cryptographic related :-).
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37 | * 4. If you include any Windows specific code (or a derivative thereof) from
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38 | * the apps directory (application code) you must include an acknowledgement:
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39 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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40 | *
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41 | * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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42 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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43 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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44 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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45 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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46 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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47 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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48 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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49 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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50 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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51 | * SUCH DAMAGE.
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52 | *
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53 | * The licence and distribution terms for any publically available version or
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54 | * derivative of this code cannot be changed. i.e. this code cannot simply be
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55 | * copied and put under another distribution licence
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56 | * [including the GNU Public Licence.]
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57 | */
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58 |
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59 | #include <stdio.h>
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60 | #include <string.h>
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61 | #include "bn_lcl.h"
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62 | #include "openssl_mods.h"
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63 |
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64 | int BN_lshift1(BIGNUM *r, BIGNUM *a)
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65 | {
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66 | register BN_ULONG *ap,*rp,t,c;
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67 | int i;
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68 |
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69 | if (r != a)
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70 | {
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71 | r->neg=a->neg;
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72 | if (bn_wexpand(r,a->top+1) == NULL) return(0);
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73 | r->top=a->top;
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74 | }
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75 | else
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76 | {
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77 | if (bn_wexpand(r,a->top+1) == NULL) return(0);
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78 | }
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79 | ap=a->d;
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80 | rp=r->d;
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81 | c=0;
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82 | for (i=0; i<a->top; i++)
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83 | {
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84 | t= *(ap++);
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85 | *(rp++)=((t<<1)|c)&BN_MASK2;
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86 | c=(t & BN_TBIT)?1:0;
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87 | }
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88 | if (c)
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89 | {
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90 | *rp=1;
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91 | r->top++;
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92 | }
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93 | return(1);
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94 | }
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95 |
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96 | int BN_rshift1(BIGNUM *r, BIGNUM *a)
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97 | {
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98 | BN_ULONG *ap,*rp,t,c;
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99 | int i;
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100 |
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101 | if (BN_is_zero(a))
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102 | {
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103 | BN_zero(r);
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104 | return(1);
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105 | }
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106 | if (a != r)
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107 | {
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108 | if (bn_wexpand(r,a->top) == NULL) return(0);
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109 | r->top=a->top;
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110 | r->neg=a->neg;
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111 | }
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112 | ap=a->d;
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113 | rp=r->d;
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114 | c=0;
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115 | for (i=a->top-1; i>=0; i--)
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116 | {
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117 | t=ap[i];
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118 | rp[i]=((t>>1)&BN_MASK2)|c;
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119 | c=(t&1)?BN_TBIT:0;
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120 | }
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121 | bn_fix_top(r);
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122 | return(1);
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123 | }
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124 |
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125 | int BN_lshift(BIGNUM *r, const BIGNUM *a, int n)
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126 | {
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127 | int i,nw,lb,rb;
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128 | BN_ULONG *t,*f;
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129 | BN_ULONG l;
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130 |
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131 | r->neg=a->neg;
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132 | if (bn_wexpand(r,a->top+(n/BN_BITS2)+1) == NULL) return(0);
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133 | nw=n/BN_BITS2;
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134 | lb=n%BN_BITS2;
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135 | rb=BN_BITS2-lb;
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136 | f=a->d;
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137 | t=r->d;
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138 | t[a->top+nw]=0;
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139 | if (lb == 0)
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140 | for (i=a->top-1; i>=0; i--)
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141 | t[nw+i]=f[i];
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142 | else
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143 | for (i=a->top-1; i>=0; i--)
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144 | {
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145 | l=f[i];
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146 | t[nw+i+1]|=(l>>rb)&BN_MASK2;
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147 | t[nw+i]=(l<<lb)&BN_MASK2;
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148 | }
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149 | memset(t,0,nw*sizeof(t[0]));
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150 | /* for (i=0; i<nw; i++)
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151 | t[i]=0;*/
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152 | r->top=a->top+nw+1;
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153 | bn_fix_top(r);
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154 | return(1);
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155 | }
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156 |
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157 | int BN_rshift(BIGNUM *r, BIGNUM *a, int n)
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158 | {
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159 | int i,j,nw,lb,rb;
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160 | BN_ULONG *t,*f;
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161 | BN_ULONG l,tmp;
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162 |
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163 | nw=n/BN_BITS2;
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164 | rb=n%BN_BITS2;
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165 | lb=BN_BITS2-rb;
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166 | if (nw > a->top || a->top == 0)
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167 | {
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168 | BN_zero(r);
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169 | return(1);
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170 | }
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171 | if (r != a)
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172 | {
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173 | r->neg=a->neg;
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174 | if (bn_wexpand(r,a->top-nw+1) == NULL) return(0);
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175 | }
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176 | else
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177 | {
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178 | if (n == 0)
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179 | return 1; /* or the copying loop will go berserk */
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180 | }
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181 |
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182 | f= &(a->d[nw]);
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183 | t=r->d;
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184 | j=a->top-nw;
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185 | r->top=j;
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186 |
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187 | if (rb == 0)
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188 | {
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189 | for (i=j+1; i > 0; i--)
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190 | *(t++)= *(f++);
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191 | }
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192 | else
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193 | {
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194 | l= *(f++);
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195 | for (i=1; i<j; i++)
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196 | {
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197 | tmp =(l>>rb)&BN_MASK2;
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198 | l= *(f++);
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199 | *(t++) =(tmp|(l<<lb))&BN_MASK2;
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200 | }
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201 | *(t++) =(l>>rb)&BN_MASK2;
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202 | }
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203 | *t=0;
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204 | bn_fix_top(r);
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205 | return(1);
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206 | }
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