diff options
Diffstat (limited to 'sysdeps/powerpc/powerpc32/sub_n.S')
| -rw-r--r-- | sysdeps/powerpc/powerpc32/sub_n.S | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/sysdeps/powerpc/powerpc32/sub_n.S b/sysdeps/powerpc/powerpc32/sub_n.S new file mode 100644 index 0000000000..3ebd22e30e --- /dev/null +++ b/sysdeps/powerpc/powerpc32/sub_n.S @@ -0,0 +1,78 @@ +/* Subtract two limb vectors of equal, non-zero length for PowerPC. + Copyright (C) 1997, 1999, 2000 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <sysdep.h> +#include <bp-sym.h> +#include <bp-asm.h> + +/* mp_limb_t mpn_sub_n (mp_ptr res_ptr, mp_srcptr s1_ptr, mp_srcptr s2_ptr, + mp_size_t size) + Calculate s1-s2 and put result in res_ptr; return borrow, 0 or 1. */ + +/* Note on optimisation: This code is optimal for the 601. Almost every other + possible 2-unrolled inner loop will not be. Also, watch out for the + alignment... */ + +EALIGN (BP_SYM (__mpn_sub_n), 3, 1) + +#if __BOUNDED_POINTERS__ + slwi r10,r6,2 /* convert limbs to bytes */ + CHECK_BOUNDS_BOTH_WIDE (r3, r8, r9, r10) + CHECK_BOUNDS_BOTH_WIDE (r4, r8, r9, r10) + CHECK_BOUNDS_BOTH_WIDE (r5, r8, r9, r10) +#endif + +/* Set up for loop below. */ + mtcrf 0x01,r6 + srwi. r7,r6,1 + mtctr r7 + bt 31,L(2) + +/* Set the carry (clear the borrow). */ + subfc r0,r0,r0 +/* Adjust pointers for loop. */ + addi r3,r3,-4 + addi r4,r4,-4 + addi r5,r5,-4 + b L(0) + +L(2): lwz r7,0(r5) + lwz r6,0(r4) + subfc r6,r7,r6 + stw r6,0(r3) + beq L(1) + +/* Align start of loop to an odd word boundary to guarantee that the + last two words can be fetched in one access (for 601). This turns + out to be important. */ +L(0): + lwz r9,4(r4) + lwz r8,4(r5) + lwzu r6,8(r4) + lwzu r7,8(r5) + subfe r8,r8,r9 + stw r8,4(r3) + subfe r6,r7,r6 + stwu r6,8(r3) + bdnz L(0) +/* Return the borrow. */ +L(1): subfe r3,r3,r3 + neg r3,r3 + blr +END (BP_SYM (__mpn_sub_n)) |