diff options
| author | Jonathan Herman <hermanjl@cs.unc.edu> | 2013-01-22 10:38:37 -0500 |
|---|---|---|
| committer | Jonathan Herman <hermanjl@cs.unc.edu> | 2013-01-22 10:38:37 -0500 |
| commit | fcc9d2e5a6c89d22b8b773a64fb4ad21ac318446 (patch) | |
| tree | a57612d1888735a2ec7972891b68c1ac5ec8faea /arch/sparc/lib/sdiv.S | |
| parent | 8dea78da5cee153b8af9c07a2745f6c55057fe12 (diff) | |
Diffstat (limited to 'arch/sparc/lib/sdiv.S')
| -rw-r--r-- | arch/sparc/lib/sdiv.S | 381 |
1 files changed, 381 insertions, 0 deletions
diff --git a/arch/sparc/lib/sdiv.S b/arch/sparc/lib/sdiv.S new file mode 100644 index 00000000000..f0a0d4e4db7 --- /dev/null +++ b/arch/sparc/lib/sdiv.S | |||
| @@ -0,0 +1,381 @@ | |||
| 1 | /* | ||
| 2 | * sdiv.S: This routine was taken from glibc-1.09 and is covered | ||
| 3 | * by the GNU Library General Public License Version 2. | ||
| 4 | */ | ||
| 5 | |||
| 6 | |||
| 7 | /* This file is generated from divrem.m4; DO NOT EDIT! */ | ||
| 8 | /* | ||
| 9 | * Division and remainder, from Appendix E of the Sparc Version 8 | ||
| 10 | * Architecture Manual, with fixes from Gordon Irlam. | ||
| 11 | */ | ||
| 12 | |||
| 13 | /* | ||
| 14 | * Input: dividend and divisor in %o0 and %o1 respectively. | ||
| 15 | * | ||
| 16 | * m4 parameters: | ||
| 17 | * .div name of function to generate | ||
| 18 | * div div=div => %o0 / %o1; div=rem => %o0 % %o1 | ||
| 19 | * true true=true => signed; true=false => unsigned | ||
| 20 | * | ||
| 21 | * Algorithm parameters: | ||
| 22 | * N how many bits per iteration we try to get (4) | ||
| 23 | * WORDSIZE total number of bits (32) | ||
| 24 | * | ||
| 25 | * Derived constants: | ||
| 26 | * TOPBITS number of bits in the top decade of a number | ||
| 27 | * | ||
| 28 | * Important variables: | ||
| 29 | * Q the partial quotient under development (initially 0) | ||
| 30 | * R the remainder so far, initially the dividend | ||
| 31 | * ITER number of main division loop iterations required; | ||
| 32 | * equal to ceil(log2(quotient) / N). Note that this | ||
| 33 | * is the log base (2^N) of the quotient. | ||
| 34 | * V the current comparand, initially divisor*2^(ITER*N-1) | ||
| 35 | * | ||
| 36 | * Cost: | ||
| 37 | * Current estimate for non-large dividend is | ||
| 38 | * ceil(log2(quotient) / N) * (10 + 7N/2) + C | ||
| 39 | * A large dividend is one greater than 2^(31-TOPBITS) and takes a | ||
| 40 | * different path, as the upper bits of the quotient must be developed | ||
| 41 | * one bit at a time. | ||
| 42 | */ | ||
| 43 | |||
| 44 | |||
| 45 | .globl .div | ||
| 46 | .globl _Div | ||
| 47 | .div: | ||
| 48 | _Div: /* needed for export */ | ||
| 49 | ! compute sign of result; if neither is negative, no problem | ||
| 50 | orcc %o1, %o0, %g0 ! either negative? | ||
| 51 | bge 2f ! no, go do the divide | ||
| 52 | xor %o1, %o0, %g2 ! compute sign in any case | ||
| 53 | |||
| 54 | tst %o1 | ||
| 55 | bge 1f | ||
| 56 | tst %o0 | ||
| 57 | ! %o1 is definitely negative; %o0 might also be negative | ||
| 58 | bge 2f ! if %o0 not negative... | ||
| 59 | sub %g0, %o1, %o1 ! in any case, make %o1 nonneg | ||
| 60 | 1: ! %o0 is negative, %o1 is nonnegative | ||
| 61 | sub %g0, %o0, %o0 ! make %o0 nonnegative | ||
| 62 | 2: | ||
| 63 | |||
| 64 | ! Ready to divide. Compute size of quotient; scale comparand. | ||
| 65 | orcc %o1, %g0, %o5 | ||
| 66 | bne 1f | ||
| 67 | mov %o0, %o3 | ||
| 68 | |||
| 69 | ! Divide by zero trap. If it returns, return 0 (about as | ||
| 70 | ! wrong as possible, but that is what SunOS does...). | ||
| 71 | ta ST_DIV0 | ||
| 72 | retl | ||
| 73 | clr %o0 | ||
| 74 | |||
| 75 | 1: | ||
| 76 | cmp %o3, %o5 ! if %o1 exceeds %o0, done | ||
| 77 | blu Lgot_result ! (and algorithm fails otherwise) | ||
| 78 | clr %o2 | ||
| 79 | |||
| 80 | sethi %hi(1 << (32 - 4 - 1)), %g1 | ||
| 81 | |||
| 82 | cmp %o3, %g1 | ||
| 83 | blu Lnot_really_big | ||
| 84 | clr %o4 | ||
| 85 | |||
| 86 | ! Here the dividend is >= 2**(31-N) or so. We must be careful here, | ||
| 87 | ! as our usual N-at-a-shot divide step will cause overflow and havoc. | ||
| 88 | ! The number of bits in the result here is N*ITER+SC, where SC <= N. | ||
| 89 | ! Compute ITER in an unorthodox manner: know we need to shift V into | ||
| 90 | ! the top decade: so do not even bother to compare to R. | ||
| 91 | 1: | ||
| 92 | cmp %o5, %g1 | ||
| 93 | bgeu 3f | ||
| 94 | mov 1, %g7 | ||
| 95 | |||
| 96 | sll %o5, 4, %o5 | ||
| 97 | |||
| 98 | b 1b | ||
| 99 | add %o4, 1, %o4 | ||
| 100 | |||
| 101 | ! Now compute %g7. | ||
| 102 | 2: | ||
| 103 | addcc %o5, %o5, %o5 | ||
| 104 | bcc Lnot_too_big | ||
| 105 | add %g7, 1, %g7 | ||
| 106 | |||
| 107 | ! We get here if the %o1 overflowed while shifting. | ||
| 108 | ! This means that %o3 has the high-order bit set. | ||
| 109 | ! Restore %o5 and subtract from %o3. | ||
| 110 | sll %g1, 4, %g1 ! high order bit | ||
| 111 | srl %o5, 1, %o5 ! rest of %o5 | ||
| 112 | add %o5, %g1, %o5 | ||
| 113 | |||
| 114 | b Ldo_single_div | ||
| 115 | sub %g7, 1, %g7 | ||
| 116 | |||
| 117 | Lnot_too_big: | ||
| 118 | 3: | ||
| 119 | cmp %o5, %o3 | ||
| 120 | blu 2b | ||
| 121 | nop | ||
| 122 | |||
| 123 | be Ldo_single_div | ||
| 124 | nop | ||
| 125 | /* NB: these are commented out in the V8-Sparc manual as well */ | ||
| 126 | /* (I do not understand this) */ | ||
| 127 | ! %o5 > %o3: went too far: back up 1 step | ||
| 128 | ! srl %o5, 1, %o5 | ||
| 129 | ! dec %g7 | ||
| 130 | ! do single-bit divide steps | ||
| 131 | ! | ||
| 132 | ! We have to be careful here. We know that %o3 >= %o5, so we can do the | ||
| 133 | ! first divide step without thinking. BUT, the others are conditional, | ||
| 134 | ! and are only done if %o3 >= 0. Because both %o3 and %o5 may have the high- | ||
| 135 | ! order bit set in the first step, just falling into the regular | ||
| 136 | ! division loop will mess up the first time around. | ||
| 137 | ! So we unroll slightly... | ||
| 138 | Ldo_single_div: | ||
| 139 | subcc %g7, 1, %g7 | ||
| 140 | bl Lend_regular_divide | ||
| 141 | nop | ||
| 142 | |||
| 143 | sub %o3, %o5, %o3 | ||
| 144 | mov 1, %o2 | ||
| 145 | |||
| 146 | b Lend_single_divloop | ||
| 147 | nop | ||
| 148 | Lsingle_divloop: | ||
| 149 | sll %o2, 1, %o2 | ||
| 150 | |||
| 151 | bl 1f | ||
| 152 | srl %o5, 1, %o5 | ||
| 153 | ! %o3 >= 0 | ||
| 154 | sub %o3, %o5, %o3 | ||
| 155 | |||
| 156 | b 2f | ||
| 157 | add %o2, 1, %o2 | ||
| 158 | 1: ! %o3 < 0 | ||
| 159 | add %o3, %o5, %o3 | ||
| 160 | sub %o2, 1, %o2 | ||
| 161 | 2: | ||
| 162 | Lend_single_divloop: | ||
| 163 | subcc %g7, 1, %g7 | ||
| 164 | bge Lsingle_divloop | ||
| 165 | tst %o3 | ||
| 166 | |||
| 167 | b,a Lend_regular_divide | ||
| 168 | |||
| 169 | Lnot_really_big: | ||
| 170 | 1: | ||
| 171 | sll %o5, 4, %o5 | ||
| 172 | cmp %o5, %o3 | ||
| 173 | bleu 1b | ||
| 174 | addcc %o4, 1, %o4 | ||
| 175 | |||
| 176 | be Lgot_result | ||
| 177 | sub %o4, 1, %o4 | ||
| 178 | |||
| 179 | tst %o3 ! set up for initial iteration | ||
| 180 | Ldivloop: | ||
| 181 | sll %o2, 4, %o2 | ||
| 182 | ! depth 1, accumulated bits 0 | ||
| 183 | bl L.1.16 | ||
| 184 | srl %o5,1,%o5 | ||
| 185 | ! remainder is positive | ||
| 186 | subcc %o3,%o5,%o3 | ||
| 187 | ! depth 2, accumulated bits 1 | ||
| 188 | bl L.2.17 | ||
| 189 | srl %o5,1,%o5 | ||
| 190 | ! remainder is positive | ||
| 191 | subcc %o3,%o5,%o3 | ||
| 192 | ! depth 3, accumulated bits 3 | ||
| 193 | bl L.3.19 | ||
| 194 | srl %o5,1,%o5 | ||
| 195 | ! remainder is positive | ||
| 196 | subcc %o3,%o5,%o3 | ||
| 197 | ! depth 4, accumulated bits 7 | ||
| 198 | bl L.4.23 | ||
| 199 | srl %o5,1,%o5 | ||
| 200 | ! remainder is positive | ||
| 201 | subcc %o3,%o5,%o3 | ||
| 202 | b 9f | ||
| 203 | add %o2, (7*2+1), %o2 | ||
| 204 | |||
| 205 | L.4.23: | ||
| 206 | ! remainder is negative | ||
| 207 | addcc %o3,%o5,%o3 | ||
| 208 | b 9f | ||
| 209 | add %o2, (7*2-1), %o2 | ||
| 210 | |||
| 211 | L.3.19: | ||
| 212 | ! remainder is negative | ||
| 213 | addcc %o3,%o5,%o3 | ||
| 214 | ! depth 4, accumulated bits 5 | ||
| 215 | bl L.4.21 | ||
| 216 | srl %o5,1,%o5 | ||
| 217 | ! remainder is positive | ||
| 218 | subcc %o3,%o5,%o3 | ||
| 219 | b 9f | ||
| 220 | add %o2, (5*2+1), %o2 | ||
| 221 | |||
| 222 | L.4.21: | ||
| 223 | ! remainder is negative | ||
| 224 | addcc %o3,%o5,%o3 | ||
| 225 | b 9f | ||
| 226 | add %o2, (5*2-1), %o2 | ||
| 227 | |||
| 228 | L.2.17: | ||
| 229 | ! remainder is negative | ||
| 230 | addcc %o3,%o5,%o3 | ||
| 231 | ! depth 3, accumulated bits 1 | ||
| 232 | bl L.3.17 | ||
| 233 | srl %o5,1,%o5 | ||
| 234 | ! remainder is positive | ||
| 235 | subcc %o3,%o5,%o3 | ||
| 236 | ! depth 4, accumulated bits 3 | ||
| 237 | bl L.4.19 | ||
| 238 | srl %o5,1,%o5 | ||
| 239 | ! remainder is positive | ||
| 240 | subcc %o3,%o5,%o3 | ||
| 241 | b 9f | ||
| 242 | add %o2, (3*2+1), %o2 | ||
| 243 | |||
| 244 | L.4.19: | ||
| 245 | ! remainder is negative | ||
| 246 | addcc %o3,%o5,%o3 | ||
| 247 | b 9f | ||
| 248 | add %o2, (3*2-1), %o2 | ||
| 249 | |||
| 250 | |||
| 251 | L.3.17: | ||
| 252 | ! remainder is negative | ||
| 253 | addcc %o3,%o5,%o3 | ||
| 254 | ! depth 4, accumulated bits 1 | ||
| 255 | bl L.4.17 | ||
| 256 | srl %o5,1,%o5 | ||
| 257 | ! remainder is positive | ||
| 258 | subcc %o3,%o5,%o3 | ||
| 259 | b 9f | ||
| 260 | add %o2, (1*2+1), %o2 | ||
| 261 | |||
| 262 | L.4.17: | ||
| 263 | ! remainder is negative | ||
| 264 | addcc %o3,%o5,%o3 | ||
| 265 | b 9f | ||
| 266 | add %o2, (1*2-1), %o2 | ||
| 267 | |||
| 268 | L.1.16: | ||
| 269 | ! remainder is negative | ||
| 270 | addcc %o3,%o5,%o3 | ||
| 271 | ! depth 2, accumulated bits -1 | ||
| 272 | bl L.2.15 | ||
| 273 | srl %o5,1,%o5 | ||
| 274 | ! remainder is positive | ||
| 275 | subcc %o3,%o5,%o3 | ||
| 276 | ! depth 3, accumulated bits -1 | ||
| 277 | bl L.3.15 | ||
| 278 | srl %o5,1,%o5 | ||
| 279 | ! remainder is positive | ||
| 280 | subcc %o3,%o5,%o3 | ||
| 281 | ! depth 4, accumulated bits -1 | ||
| 282 | bl L.4.15 | ||
| 283 | srl %o5,1,%o5 | ||
| 284 | ! remainder is positive | ||
| 285 | subcc %o3,%o5,%o3 | ||
| 286 | b 9f | ||
| 287 | add %o2, (-1*2+1), %o2 | ||
| 288 | |||
| 289 | L.4.15: | ||
| 290 | ! remainder is negative | ||
| 291 | addcc %o3,%o5,%o3 | ||
| 292 | b 9f | ||
| 293 | add %o2, (-1*2-1), %o2 | ||
| 294 | |||
| 295 | L.3.15: | ||
| 296 | ! remainder is negative | ||
| 297 | addcc %o3,%o5,%o3 | ||
| 298 | ! depth 4, accumulated bits -3 | ||
| 299 | bl L.4.13 | ||
| 300 | srl %o5,1,%o5 | ||
| 301 | ! remainder is positive | ||
| 302 | subcc %o3,%o5,%o3 | ||
| 303 | b 9f | ||
| 304 | add %o2, (-3*2+1), %o2 | ||
| 305 | |||
| 306 | L.4.13: | ||
| 307 | ! remainder is negative | ||
| 308 | addcc %o3,%o5,%o3 | ||
| 309 | b 9f | ||
| 310 | add %o2, (-3*2-1), %o2 | ||
| 311 | |||
| 312 | L.2.15: | ||
| 313 | ! remainder is negative | ||
| 314 | addcc %o3,%o5,%o3 | ||
| 315 | ! depth 3, accumulated bits -3 | ||
| 316 | bl L.3.13 | ||
| 317 | srl %o5,1,%o5 | ||
| 318 | ! remainder is positive | ||
| 319 | subcc %o3,%o5,%o3 | ||
| 320 | ! depth 4, accumulated bits -5 | ||
| 321 | bl L.4.11 | ||
| 322 | srl %o5,1,%o5 | ||
| 323 | ! remainder is positive | ||
| 324 | subcc %o3,%o5,%o3 | ||
| 325 | b 9f | ||
| 326 | add %o2, (-5*2+1), %o2 | ||
| 327 | |||
| 328 | L.4.11: | ||
| 329 | ! remainder is negative | ||
| 330 | addcc %o3,%o5,%o3 | ||
| 331 | b 9f | ||
| 332 | add %o2, (-5*2-1), %o2 | ||
| 333 | |||
| 334 | L.3.13: | ||
| 335 | ! remainder is negative | ||
| 336 | addcc %o3,%o5,%o3 | ||
| 337 | ! depth 4, accumulated bits -7 | ||
| 338 | bl L.4.9 | ||
| 339 | srl %o5,1,%o5 | ||
| 340 | ! remainder is positive | ||
| 341 | subcc %o3,%o5,%o3 | ||
| 342 | b 9f | ||
| 343 | add %o2, (-7*2+1), %o2 | ||
| 344 | |||
| 345 | L.4.9: | ||
| 346 | ! remainder is negative | ||
| 347 | addcc %o3,%o5,%o3 | ||
| 348 | b 9f | ||
| 349 | add %o2, (-7*2-1), %o2 | ||
| 350 | |||
| 351 | 9: | ||
| 352 | Lend_regular_divide: | ||
| 353 | subcc %o4, 1, %o4 | ||
| 354 | bge Ldivloop | ||
| 355 | tst %o3 | ||
| 356 | |||
| 357 | bl,a Lgot_result | ||
| 358 | ! non-restoring fixup here (one instruction only!) | ||
| 359 | sub %o2, 1, %o2 | ||
| 360 | |||
| 361 | Lgot_result: | ||
| 362 | ! check to see if answer should be < 0 | ||
| 363 | tst %g2 | ||
| 364 | bl,a 1f | ||
| 365 | sub %g0, %o2, %o2 | ||
| 366 | 1: | ||
| 367 | retl | ||
| 368 | mov %o2, %o0 | ||
| 369 | |||
| 370 | .globl .div_patch | ||
| 371 | .div_patch: | ||
| 372 | sra %o0, 0x1f, %o2 | ||
| 373 | wr %o2, 0x0, %y | ||
| 374 | nop | ||
| 375 | nop | ||
| 376 | nop | ||
| 377 | sdivcc %o0, %o1, %o0 | ||
| 378 | bvs,a 1f | ||
| 379 | xnor %o0, %g0, %o0 | ||
| 380 | 1: retl | ||
| 381 | nop | ||
