diff options
Diffstat (limited to 'sysdeps/sparc/sparc32/sdiv.S')
| -rw-r--r-- | sysdeps/sparc/sparc32/sdiv.S | 365 |
1 files changed, 11 insertions, 354 deletions
diff --git a/sysdeps/sparc/sparc32/sdiv.S b/sysdeps/sparc/sparc32/sdiv.S index ab29718827..bfc4acf2fa 100644 --- a/sysdeps/sparc/sparc32/sdiv.S +++ b/sysdeps/sparc/sparc32/sdiv.S @@ -1,363 +1,20 @@ - /* This file is generated from divrem.m4; DO NOT EDIT! */ /* - * Division and remainder, from Appendix E of the Sparc Version 8 - * Architecture Manual, with fixes from Gordon Irlam. + * Sparc v8 has divide. */ -/* - * Input: dividend and divisor in %o0 and %o1 respectively. - * - * m4 parameters: - * .div name of function to generate - * div div=div => %o0 / %o1; div=rem => %o0 % %o1 - * true true=true => signed; true=false => unsigned - * - * Algorithm parameters: - * N how many bits per iteration we try to get (4) - * WORDSIZE total number of bits (32) - * - * Derived constants: - * TOPBITS number of bits in the top decade of a number - * - * Important variables: - * Q the partial quotient under development (initially 0) - * R the remainder so far, initially the dividend - * ITER number of main division loop iterations required; - * equal to ceil(log2(quotient) / N). Note that this - * is the log base (2^N) of the quotient. - * V the current comparand, initially divisor*2^(ITER*N-1) - * - * Cost: - * Current estimate for non-large dividend is - * ceil(log2(quotient) / N) * (10 + 7N/2) + C - * A large dividend is one greater than 2^(31-TOPBITS) and takes a - * different path, as the upper bits of the quotient must be developed - * one bit at a time. - */ - - - #include <sysdep.h> -#include <sys/trap.h> ENTRY(.div) - ! compute sign of result; if neither is negative, no problem - orcc %o1, %o0, %g0 ! either negative? - bge 2f ! no, go do the divide - xor %o1, %o0, %g3 ! compute sign in any case - tst %o1 - bge 1f - tst %o0 - ! %o1 is definitely negative; %o0 might also be negative - bge 2f ! if %o0 not negative... - sub %g0, %o1, %o1 ! in any case, make %o1 nonneg -1: ! %o0 is negative, %o1 is nonnegative - sub %g0, %o0, %o0 ! make %o0 nonnegative -2: - - ! Ready to divide. Compute size of quotient; scale comparand. - orcc %o1, %g0, %o5 - bne 1f - mov %o0, %o3 - - ! Divide by zero trap. If it returns, return 0 (about as - ! wrong as possible, but that is what SunOS does...). - ta ST_DIV0 - retl - clr %o0 - -1: - cmp %o3, %o5 ! if %o1 exceeds %o0, done - blu LOC(got_result) ! (and algorithm fails otherwise) - clr %o2 - sethi %hi(1 << (32 - 4 - 1)), %g1 - cmp %o3, %g1 - blu LOC(not_really_big) - clr %o4 - - ! Here the dividend is >= 2**(31-N) or so. We must be careful here, - ! as our usual N-at-a-shot divide step will cause overflow and havoc. - ! The number of bits in the result here is N*ITER+SC, where SC <= N. - ! Compute ITER in an unorthodox manner: know we need to shift V into - ! the top decade: so do not even bother to compare to R. - 1: - cmp %o5, %g1 - bgeu 3f - mov 1, %g2 - sll %o5, 4, %o5 - b 1b - add %o4, 1, %o4 - - ! Now compute %g2. - 2: addcc %o5, %o5, %o5 - bcc LOC(not_too_big) - add %g2, 1, %g2 - - ! We get here if the %o1 overflowed while shifting. - ! This means that %o3 has the high-order bit set. - ! Restore %o5 and subtract from %o3. - sll %g1, 4, %g1 ! high order bit - srl %o5, 1, %o5 ! rest of %o5 - add %o5, %g1, %o5 - b LOC(do_single_div) - sub %g2, 1, %g2 - - LOC(not_too_big): - 3: cmp %o5, %o3 - blu 2b - nop - be LOC(do_single_div) - nop - /* NB: these are commented out in the V8-Sparc manual as well */ - /* (I do not understand this) */ - ! %o5 > %o3: went too far: back up 1 step - ! srl %o5, 1, %o5 - ! dec %g2 - ! do single-bit divide steps - ! - ! We have to be careful here. We know that %o3 >= %o5, so we can do the - ! first divide step without thinking. BUT, the others are conditional, - ! and are only done if %o3 >= 0. Because both %o3 and %o5 may have the high- - ! order bit set in the first step, just falling into the regular - ! division loop will mess up the first time around. - ! So we unroll slightly... - LOC(do_single_div): - subcc %g2, 1, %g2 - bl LOC(end_regular_divide) - nop - sub %o3, %o5, %o3 - mov 1, %o2 - b LOC(end_single_divloop) - nop - LOC(single_divloop): - sll %o2, 1, %o2 - bl 1f - srl %o5, 1, %o5 - ! %o3 >= 0 - sub %o3, %o5, %o3 - b 2f - add %o2, 1, %o2 - 1: ! %o3 < 0 - add %o3, %o5, %o3 - sub %o2, 1, %o2 - 2: - LOC(end_single_divloop): - subcc %g2, 1, %g2 - bge LOC(single_divloop) - tst %o3 - b,a LOC(end_regular_divide) - -LOC(not_really_big): -1: - sll %o5, 4, %o5 - cmp %o5, %o3 - bleu 1b - addcc %o4, 1, %o4 - be LOC(got_result) - sub %o4, 1, %o4 - - tst %o3 ! set up for initial iteration -LOC(divloop): - sll %o2, 4, %o2 - ! depth 1, accumulated bits 0 - bl LOC(1.16) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - ! depth 2, accumulated bits 1 - bl LOC(2.17) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - ! depth 3, accumulated bits 3 - bl LOC(3.19) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - ! depth 4, accumulated bits 7 - bl LOC(4.23) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - b 9f - add %o2, (7*2+1), %o2 - -LOC(4.23): - ! remainder is negative - addcc %o3,%o5,%o3 - b 9f - add %o2, (7*2-1), %o2 - - -LOC(3.19): - ! remainder is negative - addcc %o3,%o5,%o3 - ! depth 4, accumulated bits 5 - bl LOC(4.21) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - b 9f - add %o2, (5*2+1), %o2 - -LOC(4.21): - ! remainder is negative - addcc %o3,%o5,%o3 - b 9f - add %o2, (5*2-1), %o2 - - - -LOC(2.17): - ! remainder is negative - addcc %o3,%o5,%o3 - ! depth 3, accumulated bits 1 - bl LOC(3.17) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - ! depth 4, accumulated bits 3 - bl LOC(4.19) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - b 9f - add %o2, (3*2+1), %o2 - -LOC(4.19): - ! remainder is negative - addcc %o3,%o5,%o3 - b 9f - add %o2, (3*2-1), %o2 - - -LOC(3.17): - ! remainder is negative - addcc %o3,%o5,%o3 - ! depth 4, accumulated bits 1 - bl LOC(4.17) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - b 9f - add %o2, (1*2+1), %o2 - -LOC(4.17): - ! remainder is negative - addcc %o3,%o5,%o3 - b 9f - add %o2, (1*2-1), %o2 - - - - -LOC(1.16): - ! remainder is negative - addcc %o3,%o5,%o3 - ! depth 2, accumulated bits -1 - bl LOC(2.15) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - ! depth 3, accumulated bits -1 - bl LOC(3.15) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - ! depth 4, accumulated bits -1 - bl LOC(4.15) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - b 9f - add %o2, (-1*2+1), %o2 - -LOC(4.15): - ! remainder is negative - addcc %o3,%o5,%o3 - b 9f - add %o2, (-1*2-1), %o2 - - -LOC(3.15): - ! remainder is negative - addcc %o3,%o5,%o3 - ! depth 4, accumulated bits -3 - bl LOC(4.13) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - b 9f - add %o2, (-3*2+1), %o2 - -LOC(4.13): - ! remainder is negative - addcc %o3,%o5,%o3 - b 9f - add %o2, (-3*2-1), %o2 - - - -LOC(2.15): - ! remainder is negative - addcc %o3,%o5,%o3 - ! depth 3, accumulated bits -3 - bl LOC(3.13) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - ! depth 4, accumulated bits -5 - bl LOC(4.11) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - b 9f - add %o2, (-5*2+1), %o2 - -LOC(4.11): - ! remainder is negative - addcc %o3,%o5,%o3 - b 9f - add %o2, (-5*2-1), %o2 - - -LOC(3.13): - ! remainder is negative - addcc %o3,%o5,%o3 - ! depth 4, accumulated bits -7 - bl LOC(4.9) - srl %o5,1,%o5 - ! remainder is positive - subcc %o3,%o5,%o3 - b 9f - add %o2, (-7*2+1), %o2 - -LOC(4.9): - ! remainder is negative - addcc %o3,%o5,%o3 - b 9f - add %o2, (-7*2-1), %o2 - - - - -9: -LOC(end_regular_divide): - subcc %o4, 1, %o4 - bge LOC(divloop) - tst %o3 - bl,a LOC(got_result) - ! non-restoring fixup here (one instruction only!) - sub %o2, 1, %o2 - -LOC(got_result): - ! check to see if answer should be < 0 - tst %g3 - bl,a 1f - sub %g0, %o2, %o2 -1: - retl - mov %o2, %o0 + sra %o0, 31, %o2 + wr %o2, 0, %y + nop + nop + nop + sdivcc %o0, %o1, %o0 + bvs,a 1f + xnor %o0, %g0, %o0 +1: retl + nop END(.div) |