| /* Optimized strcmp implementation for PowerPC32. |
| Copyright (C) 2003 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> |
| |
| /* See strlen.s for comments on how the end-of-string testing works. */ |
| |
| /* int [r3] strncmp (const char *s1 [r3], const char *s2 [r4], size_t size [r5]) */ |
| |
| EALIGN (BP_SYM(strncmp), 4, 0) |
| |
| #define rTMP r0 |
| #define rRTN r3 |
| #define rSTR1 r3 /* first string arg */ |
| #define rSTR2 r4 /* second string arg */ |
| #define rN r5 /* max string length */ |
| /* Note: The Bounded pointer support in this code is broken. This code |
| was inherited from PPC32 and and that support was never completed. |
| Current PPC gcc does not support -fbounds-check or -fbounded-pointers. */ |
| #define rWORD1 r6 /* current word in s1 */ |
| #define rWORD2 r7 /* current word in s2 */ |
| #define rFEFE r8 /* constant 0xfefefeff (-0x01010101) */ |
| #define r7F7F r9 /* constant 0x7f7f7f7f */ |
| #define rNEG r10 /* ~(word in s1 | 0x7f7f7f7f) */ |
| #define rBITDIF r11 /* bits that differ in s1 & s2 words */ |
| |
| dcbt 0,rSTR1 |
| or rTMP, rSTR2, rSTR1 |
| lis r7F7F, 0x7f7f |
| dcbt 0,rSTR2 |
| clrlwi. rTMP, rTMP, 30 |
| cmplwi cr1, rN, 0 |
| lis rFEFE, -0x101 |
| bne L(unaligned) |
| /* We are word alligned so set up for two loops. first a word |
| loop, then fall into the byte loop if any residual. */ |
| srwi. rTMP, rN, 2 |
| clrlwi rN, rN, 30 |
| addi rFEFE, rFEFE, -0x101 |
| addi r7F7F, r7F7F, 0x7f7f |
| cmplwi cr1, rN, 0 |
| beq L(unaligned) |
| |
| mtctr rTMP /* Power4 wants mtctr 1st in dispatch group. */ |
| lwz rWORD1, 0(rSTR1) |
| lwz rWORD2, 0(rSTR2) |
| b L(g1) |
| |
| L(g0): |
| lwzu rWORD1, 4(rSTR1) |
| bne- cr1, L(different) |
| lwzu rWORD2, 4(rSTR2) |
| L(g1): add rTMP, rFEFE, rWORD1 |
| nor rNEG, r7F7F, rWORD1 |
| bdz L(tail) |
| and. rTMP, rTMP, rNEG |
| cmpw cr1, rWORD1, rWORD2 |
| beq+ L(g0) |
| |
| /* OK. We've hit the end of the string. We need to be careful that |
| we don't compare two strings as different because of gunk beyond |
| the end of the strings... */ |
| |
| L(endstring): |
| and rTMP, r7F7F, rWORD1 |
| beq cr1, L(equal) |
| add rTMP, rTMP, r7F7F |
| xor. rBITDIF, rWORD1, rWORD2 |
| |
| andc rNEG, rNEG, rTMP |
| blt- L(highbit) |
| cntlzw rBITDIF, rBITDIF |
| cntlzw rNEG, rNEG |
| addi rNEG, rNEG, 7 |
| cmpw cr1, rNEG, rBITDIF |
| sub rRTN, rWORD1, rWORD2 |
| blt- cr1, L(equal) |
| srawi rRTN, rRTN, 31 |
| ori rRTN, rRTN, 1 |
| blr |
| L(equal): |
| li rRTN, 0 |
| blr |
| |
| L(different): |
| lwzu rWORD1, -4(rSTR1) |
| xor. rBITDIF, rWORD1, rWORD2 |
| sub rRTN, rWORD1, rWORD2 |
| blt- L(highbit) |
| srawi rRTN, rRTN, 31 |
| ori rRTN, rRTN, 1 |
| blr |
| L(highbit): |
| srwi rWORD2, rWORD2, 24 |
| srwi rWORD1, rWORD1, 24 |
| sub rRTN, rWORD1, rWORD2 |
| blr |
| |
| |
| /* Oh well. In this case, we just do a byte-by-byte comparison. */ |
| .align 4 |
| L(tail): |
| and. rTMP, rTMP, rNEG |
| cmpw cr1, rWORD1, rWORD2 |
| bne- L(endstring) |
| addi rSTR1, rSTR1, 4 |
| bne- cr1, L(different) |
| addi rSTR2, rSTR2, 4 |
| cmplwi cr1, rN, 0 |
| L(unaligned): |
| mtctr rN /* Power4 wants mtctr 1st in dispatch group */ |
| bgt cr1, L(uz) |
| L(ux): |
| li rRTN, 0 |
| blr |
| .align 4 |
| L(uz): |
| lbz rWORD1, 0(rSTR1) |
| lbz rWORD2, 0(rSTR2) |
| nop |
| b L(u1) |
| L(u0): |
| lbzu rWORD2, 1(rSTR2) |
| L(u1): |
| bdz L(u3) |
| cmpwi cr1, rWORD1, 0 |
| cmpw rWORD1, rWORD2 |
| beq- cr1, L(u3) |
| lbzu rWORD1, 1(rSTR1) |
| bne- L(u2) |
| lbzu rWORD2, 1(rSTR2) |
| bdz L(u3) |
| cmpwi cr1, rWORD1, 0 |
| cmpw rWORD1, rWORD2 |
| bne- L(u3) |
| lbzu rWORD1, 1(rSTR1) |
| bne+ cr1, L(u0) |
| |
| L(u2): lbzu rWORD1, -1(rSTR1) |
| L(u3): sub rRTN, rWORD1, rWORD2 |
| blr |
| END (BP_SYM (strncmp)) |
| libc_hidden_builtin_def (strncmp) |
