diff options
Diffstat (limited to 'sysdeps/powerpc/powerpc32/power7/strnlen.S')
| -rw-r--r-- | sysdeps/powerpc/powerpc32/power7/strnlen.S | 106 |
1 files changed, 56 insertions, 50 deletions
diff --git a/sysdeps/powerpc/powerpc32/power7/strnlen.S b/sysdeps/powerpc/powerpc32/power7/strnlen.S index ed088366a2..eb52afd1a7 100644 --- a/sysdeps/powerpc/powerpc32/power7/strnlen.S +++ b/sysdeps/powerpc/powerpc32/power7/strnlen.S @@ -28,51 +28,47 @@ ENTRY (__strnlen) add r7,r3,r4 /* Calculate the last acceptable address. */ cmplwi r4,16 li r0,0 /* Word with null chars. */ + addi r7,r7,-1 ble L(small_range) - cmplw cr7,r3,r7 /* Is the address equal or less than r3? If - it's equal or less, it means size is either 0 - or a negative number. */ - ble cr7,L(proceed) - - li r7,-1 /* Make r11 the biggest if r4 <= 0. */ -L(proceed): rlwinm r6,r3,3,27,28 /* Calculate padding. */ lwz r12,0(r8) /* Load word from memory. */ cmpb r10,r12,r0 /* Check for null bytes in DWORD1. */ +#ifdef __LITTLE_ENDIAN__ + srw r10,r10,r6 + slw r10,r10,r6 +#else slw r10,r10,r6 srw r10,r10,r6 +#endif cmplwi cr7,r10,0 /* If r10 == 0, no null's have been found. */ bne cr7,L(done) - /* Are we done already? */ - addi r9,r8,4 - cmplw cr6,r9,r7 - bge cr6,L(end_max) - + clrrwi r7,r7,2 /* Address of last word. */ mtcrf 0x01,r8 /* Are we now aligned to a doubleword boundary? If so, skip to the main loop. Otherwise, go through the alignment code. */ bt 29,L(loop_setup) - /* Handle DWORD2 of pair. */ + /* Handle WORD2 of pair. */ lwzu r12,4(r8) cmpb r10,r12,r0 cmplwi cr7,r10,0 bne cr7,L(done) - /* Are we done already? */ - addi r9,r8,4 - cmplw cr6,r9,r7 - bge cr6,L(end_max) - L(loop_setup): - sub r5,r7,r9 + /* The last word we want to read in the loop below is the one + containing the last byte of the string, ie. the word at + (s + size - 1) & ~3, or r7. The first word read is at + r8 + 4, we read 2 * cnt words, so the last word read will + be at r8 + 4 + 8 * cnt - 4. Solving for cnt gives + cnt = (r7 - r8) / 8 */ + sub r5,r7,r8 srwi r6,r5,3 /* Number of loop iterations. */ mtctr r6 /* Setup the counter. */ - b L(loop) - /* Main loop to look for the null byte backwards in the string. Since + + /* Main loop to look for the null byte in the string. Since it's a small loop (< 8 instructions), align it to 32-bytes. */ .p2align 5 L(loop): @@ -88,15 +84,18 @@ L(loop): cmplwi cr7,r5,0 bne cr7,L(found) bdnz L(loop) - /* We're here because the counter reached 0, and that means we - didn't have any matches for null in the whole range. Just return - the original size. */ - addi r9,r8,4 - cmplw cr6,r9,r7 - blt cr6,L(loop_small) + + /* We may have one more word to read. */ + cmplw cr6,r8,r7 + beq cr6,L(end_max) + + lwzu r12,4(r8) + cmpb r10,r12,r0 + cmplwi cr6,r10,0 + bne cr6,L(done) L(end_max): - sub r3,r7,r3 + mr r3,r4 blr /* OK, one (or both) of the words contains a null byte. Check @@ -121,49 +120,56 @@ L(found): We need to make sure the null char is *before* the end of the range. */ L(done): - cntlzw r0,r10 /* Count leading zeroes before the match. */ - srwi r0,r0,3 /* Convert leading zeroes to bytes. */ - add r9,r8,r0 - sub r6,r9,r3 /* Length until the match. */ - cmplw r9,r7 - bgt L(end_max) - mr r3,r6 - blr - - .align 4 -L(zero): - li r3,0 +#ifdef __LITTLE_ENDIAN__ + addi r0,r10,-1 + andc r0,r0,r10 + popcntw r0,r0 +#else + cntlzw r0,r10 /* Count leading zeros before the match. */ +#endif + sub r3,r8,r3 + srwi r0,r0,3 /* Convert leading/trailing zeros to bytes. */ + add r3,r3,r0 /* Length until the match. */ + cmplw r3,r4 + blelr + mr r3,r4 blr -/* Deals with size <= 32. */ +/* Deals with size <= 16. */ .align 4 L(small_range): cmplwi r4,0 - beq L(zero) + beq L(end_max) + + clrrwi r7,r7,2 /* Address of last word. */ rlwinm r6,r3,3,27,28 /* Calculate padding. */ lwz r12,0(r8) /* Load word from memory. */ cmpb r10,r12,r0 /* Check for null bytes in WORD1. */ +#ifdef __LITTLE_ENDIAN__ + srw r10,r10,r6 + slw r10,r10,r6 +#else slw r10,r10,r6 srw r10,r10,r6 +#endif cmplwi cr7,r10,0 bne cr7,L(done) - addi r9,r8,4 - cmplw r9,r7 - bge L(end_max) - b L(loop_small) + cmplw r8,r7 + beq L(end_max) .p2align 5 L(loop_small): lwzu r12,4(r8) cmpb r10,r12,r0 - addi r9,r8,4 cmplwi cr6,r10,0 bne cr6,L(done) - cmplw r9,r7 - bge L(end_max) - b L(loop_small) + cmplw r8,r7 + bne L(loop_small) + mr r3,r4 + blr + END (__strnlen) weak_alias (__strnlen, strnlen) libc_hidden_builtin_def (strnlen) |