1 /* Signed and unsigned multiplication and division and modulus for CRIS. 2 Contributed by Axis Communications. 3 Written by Hans-Peter Nilsson <hp@axis.se>, c:a 1992. 4 5 Copyright (C) 1998-2019 Free Software Foundation, Inc. 6 7 This file is part of GCC. 8 9 GCC is free software; you can redistribute it and/or modify it 10 under the terms of the GNU General Public License as published by the 11 Free Software Foundation; either version 3, or (at your option) any 12 later version. 13 14 This file is distributed in the hope that it will be useful, but 15 WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 17 General Public License for more details. 18 19 Under Section 7 of GPL version 3, you are granted additional 20 permissions described in the GCC Runtime Library Exception, version 21 3.1, as published by the Free Software Foundation. 22 23 You should have received a copy of the GNU General Public License and 24 a copy of the GCC Runtime Library Exception along with this program; 25 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 26 <http://www.gnu.org/licenses/>. */ 27 28 29 /* Note that we provide prototypes for all "const" functions, to attach 30 the const attribute. This is necessary in 2.7.2 - adding the 31 attribute to the function *definition* is a syntax error. 32 This did not work with e.g. 2.1; back then, the return type had to 33 be "const". */ 34 35 #include "config.h" 36 37 #if defined (__CRIS_arch_version) && __CRIS_arch_version >= 3 38 #define LZ(v) __builtin_clz (v) 39 #endif 40 41 /* In (at least) the 4.7 series, GCC doesn't automatically choose the 42 most optimal strategy, possibly related to insufficient modelling of 43 delay-slot costs. */ 44 #if defined (__CRIS_arch_version) && __CRIS_arch_version >= 10 45 #define SIGNMULT(s, a) ((s) * (a)) /* Cheap multiplication, better than branch. */ 46 #else 47 #define SIGNMULT(s, a) ((s) < 0 ? -(a) : (a)) /* Branches are still better. */ 48 #endif 49 50 #if defined (L_udivsi3) || defined (L_divsi3) || defined (L_umodsi3) \ 51 || defined (L_modsi3) 52 /* Result type of divmod worker function. */ 53 struct quot_rem 54 { 55 long quot; 56 long rem; 57 }; 58 59 /* This is the worker function for div and mod. It is inlined into the 60 respective library function. Parameter A must have bit 31 == 0. */ 61 62 static __inline__ struct quot_rem 63 do_31div (unsigned long a, unsigned long b) 64 __attribute__ ((__const__, __always_inline__)); 65 66 static __inline__ struct quot_rem 67 do_31div (unsigned long a, unsigned long b) 68 { 69 /* Adjust operands and result if a is 31 bits. */ 70 long extra = 0; 71 int quot_digits = 0; 72 73 if (b == 0) 74 { 75 struct quot_rem ret; 76 ret.quot = 0xffffffff; 77 ret.rem = 0xffffffff; 78 return ret; 79 } 80 81 if (a < b) 82 return (struct quot_rem) { 0, a }; 83 84 #ifdef LZ 85 if (b <= a) 86 { 87 quot_digits = LZ (b) - LZ (a); 88 quot_digits += (a >= (b << quot_digits)); 89 b <<= quot_digits; 90 } 91 #else 92 while (b <= a) 93 { 94 b <<= 1; 95 quot_digits++; 96 } 97 #endif 98 99 /* Is a 31 bits? Note that bit 31 is handled by the caller. */ 100 if (a & 0x40000000) 101 { 102 /* Then make b:s highest bit max 0x40000000, because it must have 103 been 0x80000000 to be 1 bit higher than a. */ 104 b >>= 1; 105 106 /* Adjust a to be maximum 0x3fffffff, i.e. two upper bits zero. */ 107 if (a >= b) 108 { 109 a -= b; 110 extra = 1 << (quot_digits - 1); 111 } 112 else 113 { 114 a -= b >> 1; 115 116 /* Remember that we adjusted a by subtracting b * 2 ** Something. */ 117 extra = 1 << quot_digits; 118 } 119 120 /* The number of quotient digits will be one less, because 121 we just adjusted b. */ 122 quot_digits--; 123 } 124 125 /* Now do the division part. */ 126 127 /* Subtract b and add ones to the right when a >= b 128 i.e. "a - (b - 1) == (a - b) + 1". */ 129 b--; 130 131 #define DS __asm__ ("dstep %2,%0" : "=r" (a) : "0" (a), "r" (b)) 132 133 switch (quot_digits) 134 { 135 case 32: DS; case 31: DS; case 30: DS; case 29: DS; 136 case 28: DS; case 27: DS; case 26: DS; case 25: DS; 137 case 24: DS; case 23: DS; case 22: DS; case 21: DS; 138 case 20: DS; case 19: DS; case 18: DS; case 17: DS; 139 case 16: DS; case 15: DS; case 14: DS; case 13: DS; 140 case 12: DS; case 11: DS; case 10: DS; case 9: DS; 141 case 8: DS; case 7: DS; case 6: DS; case 5: DS; 142 case 4: DS; case 3: DS; case 2: DS; case 1: DS; 143 case 0:; 144 } 145 146 { 147 struct quot_rem ret; 148 ret.quot = (a & ((1 << quot_digits) - 1)) + extra; 149 ret.rem = a >> quot_digits; 150 return ret; 151 } 152 } 153 154 #ifdef L_udivsi3 155 unsigned long 156 __Udiv (unsigned long a, unsigned long b) __attribute__ ((__const__)); 157 158 unsigned long 159 __Udiv (unsigned long a, unsigned long b) 160 { 161 long extra = 0; 162 163 /* Adjust operands and result, if a and/or b is 32 bits. */ 164 /* Effectively: b & 0x80000000. */ 165 if ((long) b < 0) 166 return a >= b; 167 168 /* Effectively: a & 0x80000000. */ 169 if ((long) a < 0) 170 { 171 int tmp = 0; 172 173 if (b == 0) 174 return 0xffffffff; 175 #ifdef LZ 176 tmp = LZ (b); 177 #else 178 for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--) 179 ; 180 181 tmp = 31 - tmp; 182 #endif 183 184 if ((b << tmp) > a) 185 { 186 extra = 1 << (tmp-1); 187 a -= b << (tmp - 1); 188 } 189 else 190 { 191 extra = 1 << tmp; 192 a -= b << tmp; 193 } 194 } 195 196 return do_31div (a, b).quot+extra; 197 } 198 #endif /* L_udivsi3 */ 199 200 #ifdef L_divsi3 201 long 202 __Div (long a, long b) __attribute__ ((__const__)); 203 204 long 205 __Div (long a, long b) 206 { 207 long extra = 0; 208 long sign = (b < 0) ? -1 : 1; 209 long res; 210 211 /* We need to handle a == -2147483648 as expected and must while 212 doing that avoid producing a sequence like "abs (a) < 0" as GCC 213 may optimize out the test. That sequence may not be obvious as 214 we call inline functions. Testing for a being negative and 215 handling (presumably much rarer than positive) enables us to get 216 a bit of optimization for an (accumulated) reduction of the 217 penalty of the 0x80000000 special-case. */ 218 if (a < 0) 219 { 220 sign = -sign; 221 222 if ((a & 0x7fffffff) == 0) 223 { 224 /* We're at 0x80000000. Tread carefully. */ 225 a -= SIGNMULT (sign, b); 226 extra = sign; 227 } 228 a = -a; 229 } 230 231 res = do_31div (a, __builtin_labs (b)).quot; 232 return SIGNMULT (sign, res) + extra; 233 } 234 #endif /* L_divsi3 */ 235 236 237 #ifdef L_umodsi3 238 unsigned long 239 __Umod (unsigned long a, unsigned long b) __attribute__ ((__const__)); 240 241 unsigned long 242 __Umod (unsigned long a, unsigned long b) 243 { 244 /* Adjust operands and result if a and/or b is 32 bits. */ 245 if ((long) b < 0) 246 return a >= b ? a - b : a; 247 248 if ((long) a < 0) 249 { 250 int tmp = 0; 251 252 if (b == 0) 253 return a; 254 #ifdef LZ 255 tmp = LZ (b); 256 #else 257 for (tmp = 31; (((long) b & (1 << tmp)) == 0); tmp--) 258 ; 259 tmp = 31 - tmp; 260 #endif 261 262 if ((b << tmp) > a) 263 { 264 a -= b << (tmp - 1); 265 } 266 else 267 { 268 a -= b << tmp; 269 } 270 } 271 272 return do_31div (a, b).rem; 273 } 274 #endif /* L_umodsi3 */ 275 276 #ifdef L_modsi3 277 long 278 __Mod (long a, long b) __attribute__ ((__const__)); 279 280 long 281 __Mod (long a, long b) 282 { 283 long sign = 1; 284 long res; 285 286 /* We need to handle a == -2147483648 as expected and must while 287 doing that avoid producing a sequence like "abs (a) < 0" as GCC 288 may optimize out the test. That sequence may not be obvious as 289 we call inline functions. Testing for a being negative and 290 handling (presumably much rarer than positive) enables us to get 291 a bit of optimization for an (accumulated) reduction of the 292 penalty of the 0x80000000 special-case. */ 293 if (a < 0) 294 { 295 sign = -1; 296 if ((a & 0x7fffffff) == 0) 297 /* We're at 0x80000000. Tread carefully. */ 298 a += __builtin_labs (b); 299 a = -a; 300 } 301 302 res = do_31div (a, __builtin_labs (b)).rem; 303 return SIGNMULT (sign, res); 304 } 305 #endif /* L_modsi3 */ 306 #endif /* L_udivsi3 || L_divsi3 || L_umodsi3 || L_modsi3 */ 307 308 /* 309 * Local variables: 310 * eval: (c-set-style "gnu") 311 * indent-tabs-mode: t 312 * End: 313 */ 314