diff options
| -rw-r--r-- | newlib/libc/machine/aarch64/memcmp.S | 57 |
1 files changed, 55 insertions, 2 deletions
diff --git a/newlib/libc/machine/aarch64/memcmp.S b/newlib/libc/machine/aarch64/memcmp.S index 860384cc8..09be4c344 100644 --- a/newlib/libc/machine/aarch64/memcmp.S +++ b/newlib/libc/machine/aarch64/memcmp.S @@ -1,6 +1,7 @@ /* memcmp - compare memory Copyright (c) 2013, Linaro Limited + Copyright (c) 2017, Samsung Austin R&D Center All rights reserved. Redistribution and use in source and binary forms, with or without @@ -152,9 +153,61 @@ def_fn memcmp p2align=6 .p2align 6 .Lmisaligned8: + + cmp limit, #8 + b.lo .LmisalignedLt8 + +.LunalignedGe8 : + + /* Load the first dword with both src potentially unaligned. */ + ldr data1, [src1] + ldr data2, [src2] + + eor diff, data1, data2 /* Non-zero if differences found. */ + cbnz diff, .Lnot_limit + + /* Sources are not aligned: align one of the sources. */ + + and tmp1, src1, #0x7 + orr tmp3, xzr, #0x8 + sub pos, tmp3, tmp1 + + /* Increment SRC pointers by POS so SRC1 is word-aligned. */ + add src1, src1, pos + add src2, src2, pos + + sub limit, limit, pos + lsr limit_wd, limit, #3 + + cmp limit_wd, #0 + + /* save #bytes to go back to be able to read 8byte at end + pos=negative offset position to read 8 bytes when len%8 != 0 */ + and limit, limit, #7 + sub pos, limit, #8 + + b .Lstart_part_realigned + + .p2align 5 +.Lloop_part_aligned: + ldr data1, [src1], #8 + ldr data2, [src2], #8 + subs limit_wd, limit_wd, #1 +.Lstart_part_realigned: + eor diff, data1, data2 /* Non-zero if differences found. */ + cbnz diff, .Lnot_limit + b.ne .Lloop_part_aligned + + /* process leftover bytes: read the leftover bytes, starting with + negative offset - so we can load 8 bytes. */ + ldr data1, [src1, pos] + ldr data2, [src2, pos] + eor diff, data1, data2 /* Non-zero if differences found. */ + b .Lnot_limit + +.LmisalignedLt8: sub limit, limit, #1 1: - /* Perhaps we can do better than this. */ ldrb data1w, [src1], #1 ldrb data2w, [src2], #1 subs limit, limit, #1 @@ -164,4 +217,4 @@ def_fn memcmp p2align=6 ret .size memcmp, . - memcmp -#endif
\ No newline at end of file +#endif |