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111
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1 /* Signed and unsigned multiplication and division and modulus for CRIS.
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2 Contributed by Axis Communications.
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3 Written by Hans-Peter Nilsson <hp@axis.se>, c:a 1992.
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4
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5 Copyright (C) 1998-2017 Free Software Foundation, Inc.
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6
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7 This file is part of GCC.
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8
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9 GCC is free software; you can redistribute it and/or modify it
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10 under the terms of the GNU General Public License as published by the
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11 Free Software Foundation; either version 3, or (at your option) any
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12 later version.
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13
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14 This file is distributed in the hope that it will be useful, but
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15 WITHOUT ANY WARRANTY; without even the implied warranty of
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16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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17 General Public License for more details.
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18
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19 Under Section 7 of GPL version 3, you are granted additional
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20 permissions described in the GCC Runtime Library Exception, version
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21 3.1, as published by the Free Software Foundation.
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22
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23 You should have received a copy of the GNU General Public License and
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24 a copy of the GCC Runtime Library Exception along with this program;
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25 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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26 <http://www.gnu.org/licenses/>. */
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27
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28
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29 /* Note that we provide prototypes for all "const" functions, to attach
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30 the const attribute. This is necessary in 2.7.2 - adding the
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31 attribute to the function *definition* is a syntax error.
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32 This did not work with e.g. 2.1; back then, the return type had to
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33 be "const". */
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34
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35 #include "config.h"
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36
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37 #if defined (__CRIS_arch_version) && __CRIS_arch_version >= 3
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38 #define LZ(v) __builtin_clz (v)
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39 #endif
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40
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41 /* In (at least) the 4.7 series, GCC doesn't automatically choose the
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42 most optimal strategy, possibly related to insufficient modelling of
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43 delay-slot costs. */
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44 #if defined (__CRIS_arch_version) && __CRIS_arch_version >= 10
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45 #define SIGNMULT(s, a) ((s) * (a)) /* Cheap multiplication, better than branch. */
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46 #else
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47 #define SIGNMULT(s, a) ((s) < 0 ? -(a) : (a)) /* Branches are still better. */
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48 #endif
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49
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50 #if defined (L_udivsi3) || defined (L_divsi3) || defined (L_umodsi3) \
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51 || defined (L_modsi3)
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52 /* Result type of divmod worker function. */
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53 struct quot_rem
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54 {
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55 long quot;
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56 long rem;
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57 };
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58
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59 /* This is the worker function for div and mod. It is inlined into the
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60 respective library function. Parameter A must have bit 31 == 0. */
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61
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62 static __inline__ struct quot_rem
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63 do_31div (unsigned long a, unsigned long b)
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64 __attribute__ ((__const__, __always_inline__));
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65
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66 static __inline__ struct quot_rem
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67 do_31div (unsigned long a, unsigned long b)
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68 {
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69 /* Adjust operands and result if a is 31 bits. */
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70 long extra = 0;
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71 int quot_digits = 0;
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72
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73 if (b == 0)
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74 {
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75 struct quot_rem ret;
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76 ret.quot = 0xffffffff;
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77 ret.rem = 0xffffffff;
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78 return ret;
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79 }
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80
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81 if (a < b)
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82 return (struct quot_rem) { 0, a };
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83
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84 #ifdef LZ
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85 if (b <= a)
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86 {
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87 quot_digits = LZ (b) - LZ (a);
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88 quot_digits += (a >= (b << quot_digits));
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89 b <<= quot_digits;
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90 }
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91 #else
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92 while (b <= a)
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93 {
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94 b <<= 1;
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95 quot_digits++;
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96 }
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97 #endif
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98
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99 /* Is a 31 bits? Note that bit 31 is handled by the caller. */
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100 if (a & 0x40000000)
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101 {
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102 /* Then make b:s highest bit max 0x40000000, because it must have
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103 been 0x80000000 to be 1 bit higher than a. */
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104 b >>= 1;
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105
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106 /* Adjust a to be maximum 0x3fffffff, i.e. two upper bits zero. */
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107 if (a >= b)
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108 {
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109 a -= b;
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110 extra = 1 << (quot_digits - 1);
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111 }
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112 else
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113 {
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114 a -= b >> 1;
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115
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116 /* Remember that we adjusted a by subtracting b * 2 ** Something. */
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117 extra = 1 << quot_digits;
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118 }
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119
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120 /* The number of quotient digits will be one less, because
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121 we just adjusted b. */
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122 quot_digits--;
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123 }
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124
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125 /* Now do the division part. */
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126
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127 /* Subtract b and add ones to the right when a >= b
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128 i.e. "a - (b - 1) == (a - b) + 1". */
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129 b--;
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130
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131 #define DS __asm__ ("dstep %2,%0" : "=r" (a) : "0" (a), "r" (b))
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132
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133 switch (quot_digits)
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134 {
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135 case 32: DS; case 31: DS; case 30: DS; case 29: DS;
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136 case 28: DS; case 27: DS; case 26: DS; case 25: DS;
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137 case 24: DS; case 23: DS; case 22: DS; case 21: DS;
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138 case 20: DS; case 19: DS; case 18: DS; case 17: DS;
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139 case 16: DS; case 15: DS; case 14: DS; case 13: DS;
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140 case 12: DS; case 11: DS; case 10: DS; case 9: DS;
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141 case 8: DS; case 7: DS; case 6: DS; case 5: DS;
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142 case 4: DS; case 3: DS; case 2: DS; case 1: DS;
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143 case 0:;
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144 }
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145
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146 {
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147 struct quot_rem ret;
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148 ret.quot = (a & ((1 << quot_digits) - 1)) + extra;
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149 ret.rem = a >> quot_digits;
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150 return ret;
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151 }
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152 }
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153
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154 #ifdef L_udivsi3
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155 unsigned long
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156 __Udiv (unsigned long a, unsigned long b) __attribute__ ((__const__));
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157
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158 unsigned long
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159 __Udiv (unsigned long a, unsigned long b)
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160 {
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161 long extra = 0;
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162
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163 /* Adjust operands and result, if a and/or b is 32 bits. */
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164 /* Effectively: b & 0x80000000. */
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165 if ((long) b < 0)
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166 return a >= b;
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167
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168 /* Effectively: a & 0x80000000. */
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169 if ((long) a < 0)
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170 {
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171 int tmp = 0;
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172
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173 if (b == 0)
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174 return 0xffffffff;
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175 #ifdef LZ
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176 tmp = LZ (b);
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177 #else
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178 for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
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179 ;
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180
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181 tmp = 31 - tmp;
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182 #endif
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183
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184 if ((b << tmp) > a)
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185 {
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186 extra = 1 << (tmp-1);
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187 a -= b << (tmp - 1);
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188 }
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189 else
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190 {
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191 extra = 1 << tmp;
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192 a -= b << tmp;
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193 }
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194 }
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195
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196 return do_31div (a, b).quot+extra;
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197 }
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198 #endif /* L_udivsi3 */
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199
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200 #ifdef L_divsi3
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201 long
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202 __Div (long a, long b) __attribute__ ((__const__));
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203
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204 long
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205 __Div (long a, long b)
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206 {
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207 long extra = 0;
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208 long sign = (b < 0) ? -1 : 1;
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209 long res;
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210
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211 /* We need to handle a == -2147483648 as expected and must while
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212 doing that avoid producing a sequence like "abs (a) < 0" as GCC
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213 may optimize out the test. That sequence may not be obvious as
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214 we call inline functions. Testing for a being negative and
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215 handling (presumably much rarer than positive) enables us to get
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216 a bit of optimization for an (accumulated) reduction of the
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217 penalty of the 0x80000000 special-case. */
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218 if (a < 0)
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219 {
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220 sign = -sign;
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221
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222 if ((a & 0x7fffffff) == 0)
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223 {
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224 /* We're at 0x80000000. Tread carefully. */
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225 a -= SIGNMULT (sign, b);
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226 extra = sign;
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227 }
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228 a = -a;
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229 }
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230
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231 res = do_31div (a, __builtin_labs (b)).quot;
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232 return SIGNMULT (sign, res) + extra;
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233 }
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234 #endif /* L_divsi3 */
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235
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236
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237 #ifdef L_umodsi3
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238 unsigned long
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239 __Umod (unsigned long a, unsigned long b) __attribute__ ((__const__));
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240
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241 unsigned long
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242 __Umod (unsigned long a, unsigned long b)
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243 {
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244 /* Adjust operands and result if a and/or b is 32 bits. */
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245 if ((long) b < 0)
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246 return a >= b ? a - b : a;
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247
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248 if ((long) a < 0)
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249 {
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250 int tmp = 0;
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251
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252 if (b == 0)
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253 return a;
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254 #ifdef LZ
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255 tmp = LZ (b);
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256 #else
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257 for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
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258 ;
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259 tmp = 31 - tmp;
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260 #endif
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261
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262 if ((b << tmp) > a)
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263 {
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264 a -= b << (tmp - 1);
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265 }
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266 else
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267 {
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268 a -= b << tmp;
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269 }
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270 }
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271
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272 return do_31div (a, b).rem;
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273 }
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274 #endif /* L_umodsi3 */
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275
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276 #ifdef L_modsi3
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277 long
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278 __Mod (long a, long b) __attribute__ ((__const__));
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279
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280 long
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281 __Mod (long a, long b)
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282 {
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283 long sign = 1;
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284 long res;
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285
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286 /* We need to handle a == -2147483648 as expected and must while
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287 doing that avoid producing a sequence like "abs (a) < 0" as GCC
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288 may optimize out the test. That sequence may not be obvious as
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289 we call inline functions. Testing for a being negative and
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290 handling (presumably much rarer than positive) enables us to get
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291 a bit of optimization for an (accumulated) reduction of the
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292 penalty of the 0x80000000 special-case. */
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293 if (a < 0)
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294 {
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295 sign = -1;
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296 if ((a & 0x7fffffff) == 0)
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297 /* We're at 0x80000000. Tread carefully. */
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298 a += __builtin_labs (b);
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299 a = -a;
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300 }
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301
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302 res = do_31div (a, __builtin_labs (b)).rem;
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303 return SIGNMULT (sign, res);
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304 }
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305 #endif /* L_modsi3 */
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306 #endif /* L_udivsi3 || L_divsi3 || L_umodsi3 || L_modsi3 */
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307
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308 /*
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309 * Local variables:
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310 * eval: (c-set-style "gnu")
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311 * indent-tabs-mode: t
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312 * End:
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313 */
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