diff options
Diffstat (limited to 'sysdeps/arm/armv6t2/strlen.S')
| -rw-r--r-- | sysdeps/arm/armv6t2/strlen.S | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/sysdeps/arm/armv6t2/strlen.S b/sysdeps/arm/armv6t2/strlen.S new file mode 100644 index 0000000000..1706f6c6b8 --- /dev/null +++ b/sysdeps/arm/armv6t2/strlen.S @@ -0,0 +1,169 @@ +/* Copyright (C) 2010-2014 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, see + <http://www.gnu.org/licenses/>. */ + +/* + Assumes: + ARMv6T2, AArch32 + + */ + +#include <arm-features.h> /* This might #define NO_THUMB. */ +#include <sysdep.h> + +#ifdef __ARMEB__ +#define S2LO lsl +#define S2HI lsr +#else +#define S2LO lsr +#define S2HI lsl +#endif + +#ifndef NO_THUMB +/* This code is best on Thumb. */ + .thumb +#else +/* Using bne.w explicitly is desirable in Thumb mode because it helps + align the following label without a nop. In ARM mode there is no + such difference. */ +.macro bne.w label + bne \label +.endm + +/* This clobbers the condition codes, which the real Thumb cbnz instruction + does not do. But it doesn't matter for any of the uses here. */ +.macro cbnz reg, label + cmp \reg, #0 + bne \label +.endm +#endif + +/* Parameters and result. */ +#define srcin r0 +#define result r0 + +/* Internal variables. */ +#define src r1 +#define data1a r2 +#define data1b r3 +#define const_m1 r12 +#define const_0 r4 +#define tmp1 r4 /* Overlaps const_0 */ +#define tmp2 r5 + + .text + .p2align 6 +ENTRY(strlen) + sfi_pld srcin, #0 + strd r4, r5, [sp, #-8]! + cfi_adjust_cfa_offset (8) + cfi_rel_offset (r4, 0) + cfi_rel_offset (r5, 4) + cfi_remember_state + bic src, srcin, #7 + mvn const_m1, #0 + ands tmp1, srcin, #7 /* (8 - bytes) to alignment. */ + sfi_pld src, #32 + bne.w .Lmisaligned8 + mov const_0, #0 + mov result, #-8 +.Lloop_aligned: + /* Bytes 0-7. */ + sfi_breg src, \ + ldrd data1a, data1b, [\B] + sfi_pld src, #64 + add result, result, #8 +.Lstart_realigned: + uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */ + sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */ + uadd8 data1b, data1b, const_m1 + sel data1b, data1a, const_m1 /* Only used if d1a == 0. */ + cbnz data1b, .Lnull_found + + /* Bytes 8-15. */ + sfi_breg src, \ + ldrd data1a, data1b, [\B, #8] + uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */ + add result, result, #8 + sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */ + uadd8 data1b, data1b, const_m1 + sel data1b, data1a, const_m1 /* Only used if d1a == 0. */ + cbnz data1b, .Lnull_found + + /* Bytes 16-23. */ + sfi_breg src, \ + ldrd data1a, data1b, [\B, #16] + uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */ + add result, result, #8 + sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */ + uadd8 data1b, data1b, const_m1 + sel data1b, data1a, const_m1 /* Only used if d1a == 0. */ + cbnz data1b, .Lnull_found + + /* Bytes 24-31. */ + sfi_breg src, \ + ldrd data1a, data1b, [\B, #24] + add src, src, #32 + uadd8 data1a, data1a, const_m1 /* Saturating GE<0:3> set. */ + add result, result, #8 + sel data1a, const_0, const_m1 /* Select based on GE<0:3>. */ + uadd8 data1b, data1b, const_m1 + sel data1b, data1a, const_m1 /* Only used if d1a == 0. */ + cmp data1b, #0 + beq .Lloop_aligned + +.Lnull_found: + cmp data1a, #0 + itt eq + addeq result, result, #4 + moveq data1a, data1b +#ifndef __ARMEB__ + rev data1a, data1a +#endif + clz data1a, data1a + ldrd r4, r5, [sp], #8 + cfi_adjust_cfa_offset (-8) + cfi_restore (r4) + cfi_restore (r5) + add result, result, data1a, lsr #3 /* Bits -> Bytes. */ + DO_RET(lr) + +.Lmisaligned8: + cfi_restore_state + sfi_breg src, \ + ldrd data1a, data1b, [\B] + and tmp2, tmp1, #3 + rsb result, tmp1, #0 + lsl tmp2, tmp2, #3 /* Bytes -> bits. */ + tst tmp1, #4 + sfi_pld src, #64 + S2HI tmp2, const_m1, tmp2 +#ifdef NO_THUMB + mvn tmp1, tmp2 + orr data1a, data1a, tmp1 + itt ne + orrne data1b, data1b, tmp1 +#else + orn data1a, data1a, tmp2 + itt ne + ornne data1b, data1b, tmp2 +#endif + movne data1a, const_m1 + mov const_0, #0 + b .Lstart_realigned + +END(strlen) +libc_hidden_builtin_def (strlen) |