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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, 1999, 2000, 2001, 2002,
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6 2005, 2009 Free Software Foundation, Inc.
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7
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8 This file is part of GCC.
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9
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10 GCC is free software; you can redistribute it and/or modify it
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11 under the terms of the GNU General Public License as published by the
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12 Free Software Foundation; either version 3, or (at your option) any
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13 later version.
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14
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15 This file is distributed in the hope that it will be useful, but
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16 WITHOUT ANY WARRANTY; without even the implied warranty of
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17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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18 General Public License for more details.
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19
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20 Under Section 7 of GPL version 3, you are granted additional
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21 permissions described in the GCC Runtime Library Exception, version
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22 3.1, as published by the Free Software Foundation.
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23
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24 You should have received a copy of the GNU General Public License and
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25 a copy of the GCC Runtime Library Exception along with this program;
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26 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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27 <http://www.gnu.org/licenses/>. */
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28
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29
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30 /* Note that we provide prototypes for all "const" functions, to attach
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31 the const attribute. This is necessary in 2.7.2 - adding the
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32 attribute to the function *definition* is a syntax error.
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33 This did not work with e.g. 2.1; back then, the return type had to
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34 be "const". */
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35
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36 #include "config.h"
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37
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38 #if defined (__CRIS_arch_version) && __CRIS_arch_version >= 3
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39 #define LZ(v) __builtin_clz (v)
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40 #endif
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41
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42
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43 #if defined (L_udivsi3) || defined (L_divsi3) || defined (L_umodsi3) \
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44 || defined (L_modsi3)
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45 /* Result type of divmod worker function. */
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46 struct quot_rem
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47 {
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48 long quot;
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49 long rem;
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50 };
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51
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52 /* This is the worker function for div and mod. It is inlined into the
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53 respective library function. Parameter A must have bit 31 == 0. */
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54
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55 static __inline__ struct quot_rem
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56 do_31div (unsigned long a, unsigned long b)
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57 __attribute__ ((__const__, __always_inline__));
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58
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59 static __inline__ struct quot_rem
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60 do_31div (unsigned long a, unsigned long b)
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61 {
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62 /* Adjust operands and result if a is 31 bits. */
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63 long extra = 0;
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64 int quot_digits = 0;
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65
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66 if (b == 0)
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67 {
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68 struct quot_rem ret;
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69 ret.quot = 0xffffffff;
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70 ret.rem = 0xffffffff;
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71 return ret;
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72 }
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73
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74 if (a < b)
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75 return (struct quot_rem) { 0, a };
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76
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77 #ifdef LZ
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78 if (b <= a)
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79 {
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80 quot_digits = LZ (b) - LZ (a);
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81 quot_digits += (a >= (b << quot_digits));
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82 b <<= quot_digits;
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83 }
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84 #else
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85 while (b <= a)
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86 {
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87 b <<= 1;
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88 quot_digits++;
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89 }
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90 #endif
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91
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92 /* Is a 31 bits? Note that bit 31 is handled by the caller. */
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93 if (a & 0x40000000)
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94 {
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95 /* Then make b:s highest bit max 0x40000000, because it must have
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96 been 0x80000000 to be 1 bit higher than a. */
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97 b >>= 1;
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98
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99 /* Adjust a to be maximum 0x3fffffff, i.e. two upper bits zero. */
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100 if (a >= b)
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101 {
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102 a -= b;
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103 extra = 1 << (quot_digits - 1);
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104 }
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105 else
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106 {
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107 a -= b >> 1;
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108
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109 /* Remember that we adjusted a by subtracting b * 2 ** Something. */
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110 extra = 1 << quot_digits;
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111 }
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112
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113 /* The number of quotient digits will be one less, because
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114 we just adjusted b. */
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115 quot_digits--;
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116 }
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117
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118 /* Now do the division part. */
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119
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120 /* Subtract b and add ones to the right when a >= b
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121 i.e. "a - (b - 1) == (a - b) + 1". */
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122 b--;
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123
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124 #define DS __asm__ ("dstep %2,%0" : "=r" (a) : "0" (a), "r" (b))
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125
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126 switch (quot_digits)
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127 {
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128 case 32: DS; case 31: DS; case 30: DS; case 29: DS;
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129 case 28: DS; case 27: DS; case 26: DS; case 25: DS;
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130 case 24: DS; case 23: DS; case 22: DS; case 21: DS;
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131 case 20: DS; case 19: DS; case 18: DS; case 17: DS;
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132 case 16: DS; case 15: DS; case 14: DS; case 13: DS;
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133 case 12: DS; case 11: DS; case 10: DS; case 9: DS;
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134 case 8: DS; case 7: DS; case 6: DS; case 5: DS;
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135 case 4: DS; case 3: DS; case 2: DS; case 1: DS;
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136 case 0:;
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137 }
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138
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139 {
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140 struct quot_rem ret;
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141 ret.quot = (a & ((1 << quot_digits) - 1)) + extra;
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142 ret.rem = a >> quot_digits;
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143 return ret;
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144 }
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145 }
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146
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147 #ifdef L_udivsi3
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148 unsigned long
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149 __Udiv (unsigned long a, unsigned long b) __attribute__ ((__const__));
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150
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151 unsigned long
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152 __Udiv (unsigned long a, unsigned long b)
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153 {
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154 long extra = 0;
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155
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156 /* Adjust operands and result, if a and/or b is 32 bits. */
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157 /* Effectively: b & 0x80000000. */
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158 if ((long) b < 0)
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159 return a >= b;
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160
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161 /* Effectively: a & 0x80000000. */
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162 if ((long) a < 0)
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163 {
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164 int tmp = 0;
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165
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166 if (b == 0)
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167 return 0xffffffff;
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168 #ifdef LZ
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169 tmp = LZ (b);
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170 #else
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171 for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
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172 ;
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173
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174 tmp = 31 - tmp;
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175 #endif
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176
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177 if ((b << tmp) > a)
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178 {
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179 extra = 1 << (tmp-1);
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180 a -= b << (tmp - 1);
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181 }
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182 else
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183 {
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184 extra = 1 << tmp;
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185 a -= b << tmp;
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186 }
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187 }
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188
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189 return do_31div (a, b).quot+extra;
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190 }
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191 #endif /* L_udivsi3 */
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192
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193 #ifdef L_divsi3
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194 long
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195 __Div (long a, long b) __attribute__ ((__const__));
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196
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197 long
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198 __Div (long a, long b)
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199 {
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200 long extra = 0;
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201 long sign = (b < 0) ? -1 : 1;
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202
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203 /* We need to handle a == -2147483648 as expected and must while
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204 doing that avoid producing a sequence like "abs (a) < 0" as GCC
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205 may optimize out the test. That sequence may not be obvious as
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206 we call inline functions. Testing for a being negative and
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207 handling (presumably much rarer than positive) enables us to get
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208 a bit of optimization for an (accumulated) reduction of the
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209 penalty of the 0x80000000 special-case. */
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210 if (a < 0)
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211 {
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212 sign = -sign;
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213
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214 if ((a & 0x7fffffff) == 0)
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215 {
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216 /* We're at 0x80000000. Tread carefully. */
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217 a -= b * sign;
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218 extra = sign;
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219 }
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220 a = -a;
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221 }
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222
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223 /* We knowingly penalize pre-v10 models by multiplication with the
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224 sign. */
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225 return sign * do_31div (a, __builtin_labs (b)).quot + extra;
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226 }
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227 #endif /* L_divsi3 */
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228
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229
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230 #ifdef L_umodsi3
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231 unsigned long
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232 __Umod (unsigned long a, unsigned long b) __attribute__ ((__const__));
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233
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234 unsigned long
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235 __Umod (unsigned long a, unsigned long b)
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236 {
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237 /* Adjust operands and result if a and/or b is 32 bits. */
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238 if ((long) b < 0)
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239 return a >= b ? a - b : a;
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240
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241 if ((long) a < 0)
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242 {
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243 int tmp = 0;
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244
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245 if (b == 0)
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246 return a;
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247 #ifdef LZ
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248 tmp = LZ (b);
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249 #else
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250 for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--)
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251 ;
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252 tmp = 31 - tmp;
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253 #endif
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254
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255 if ((b << tmp) > a)
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256 {
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257 a -= b << (tmp - 1);
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258 }
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259 else
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260 {
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261 a -= b << tmp;
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262 }
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263 }
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264
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265 return do_31div (a, b).rem;
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266 }
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267 #endif /* L_umodsi3 */
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268
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269 #ifdef L_modsi3
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270 long
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271 __Mod (long a, long b) __attribute__ ((__const__));
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272
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273 long
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274 __Mod (long a, long b)
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275 {
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276 long sign = 1;
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277
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278 /* We need to handle a == -2147483648 as expected and must while
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279 doing that avoid producing a sequence like "abs (a) < 0" as GCC
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280 may optimize out the test. That sequence may not be obvious as
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281 we call inline functions. Testing for a being negative and
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282 handling (presumably much rarer than positive) enables us to get
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283 a bit of optimization for an (accumulated) reduction of the
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284 penalty of the 0x80000000 special-case. */
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285 if (a < 0)
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286 {
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287 sign = -1;
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288 if ((a & 0x7fffffff) == 0)
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289 /* We're at 0x80000000. Tread carefully. */
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290 a += __builtin_labs (b);
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291 a = -a;
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292 }
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293
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294 return sign * do_31div (a, __builtin_labs (b)).rem;
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295 }
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296 #endif /* L_modsi3 */
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297 #endif /* L_udivsi3 || L_divsi3 || L_umodsi3 || L_modsi3 */
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298
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299 /*
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300 * Local variables:
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301 * eval: (c-set-style "gnu")
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302 * indent-tabs-mode: t
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303 * End:
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304 */
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