diff options
Diffstat (limited to 'libc/string/arc/strchr.S')
| -rw-r--r-- | libc/string/arc/strchr.S | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/libc/string/arc/strchr.S b/libc/string/arc/strchr.S new file mode 100644 index 000000000..443993589 --- /dev/null +++ b/libc/string/arc/strchr.S @@ -0,0 +1,138 @@ +/* + * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com) + * Copyright (C) 2007 ARC International (UK) LTD + * + * Licensed under the LGPL v2.1 or later, see the file COPYING.LIB in this tarball. + */ + +#include <sysdep.h> +#include <features.h> + +/* ARC700 has a relatively long pipeline and branch prediction, so we want + to avoid branches that are hard to predict. On the other hand, the + presence of the norm instruction makes it easier to operate on whole + words branch-free. */ + +ENTRY(strchr) + extb_s r1,r1 + asl r5,r1,8 + bmsk r2,r0,1 + or r5,r5,r1 + mov_s r3,0x01010101 + breq.d r2,r0,.Laligned + asl r4,r5,16 + sub_s r0,r0,r2 + asl r7,r2,3 + ld_s r2,[r0] +#ifdef __LITTLE_ENDIAN__ + asl r7,r3,r7 +#else + lsr r7,r3,r7 +#endif + or r5,r5,r4 + ror r4,r3 + sub r12,r2,r7 + bic_s r12,r12,r2 + and r12,r12,r4 + brne.d r12,0,.Lfound0_ua + xor r6,r2,r5 + ld.a r2,[r0,4] + sub r12,r6,r7 + bic r12,r12,r6 +#ifdef __LITTLE_ENDIAN__ + and r7,r12,r4 + breq r7,0,.Loop ; For speed, we want this branch to be unaligned. + b .Lfound_char ; Likewise this one. +#else + and r12,r12,r4 + breq r12,0,.Loop ; For speed, we want this branch to be unaligned. + lsr_s r12,r12,7 + bic r2,r7,r6 + b.d .Lfound_char_b + and_s r2,r2,r12 +#endif +; /* We require this code address to be unaligned for speed... */ +.Laligned: + ld_s r2,[r0] + or r5,r5,r4 + ror r4,r3 +; /* ... so that this code address is aligned, for itself and ... */ +.Loop: + sub r12,r2,r3 + bic_s r12,r12,r2 + and r12,r12,r4 + brne.d r12,0,.Lfound0 + xor r6,r2,r5 + ld.a r2,[r0,4] + sub r12,r6,r3 + bic r12,r12,r6 + and r7,r12,r4 + breq r7,0,.Loop /* ... so that this branch is unaligned. */ + ; Found searched-for character. r0 has already advanced to next word. +#ifdef __LITTLE_ENDIAN__ +/* We only need the information about the first matching byte + (i.e. the least significant matching byte) to be exact, + hence there is no problem with carry effects. */ +.Lfound_char: + sub r3,r7,1 + bic r3,r3,r7 + norm r2,r3 + sub_s r0,r0,1 + asr_s r2,r2,3 + j.d [blink] + sub_s r0,r0,r2 + + .balign 4 +.Lfound0_ua: + mov r3,r7 +.Lfound0: + sub r3,r6,r3 + bic r3,r3,r6 + and r2,r3,r4 + or_s r12,r12,r2 + sub_s r3,r12,1 + bic_s r3,r3,r12 + norm r3,r3 + add_s r0,r0,3 + asr_s r12,r3,3 + asl.f 0,r2,r3 + sub_s r0,r0,r12 + j_s.d [blink] + mov.pl r0,0 +#else /* BIG ENDIAN */ +.Lfound_char: + lsr r7,r7,7 + + bic r2,r7,r6 +.Lfound_char_b: + norm r2,r2 + sub_s r0,r0,4 + asr_s r2,r2,3 + j.d [blink] + add_s r0,r0,r2 + +.Lfound0_ua: + mov_s r3,r7 +.Lfound0: + asl_s r2,r2,7 + or r7,r6,r4 + bic_s r12,r12,r2 + sub r2,r7,r3 + or r2,r2,r6 + bic r12,r2,r12 + bic.f r3,r4,r12 + norm r3,r3 + + add.pl r3,r3,1 + asr_s r12,r3,3 + asl.f 0,r2,r3 + add_s r0,r0,r12 + j_s.d [blink] + mov.mi r0,0 +#endif /* ENDIAN */ +END(strchr) +libc_hidden_def(strchr) + +#ifdef __UCLIBC_SUSV3_LEGACY__ +strong_alias(strchr,index) +#endif |