diff options
Diffstat (limited to 'libc/string/metag/memchr.S')
-rw-r--r-- | libc/string/metag/memchr.S | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/libc/string/metag/memchr.S b/libc/string/metag/memchr.S new file mode 100644 index 000000000..8b48d863c --- /dev/null +++ b/libc/string/metag/memchr.S @@ -0,0 +1,156 @@ +! Copyright (C) 2013 Imagination Technologies Ltd. +! +! Licensed under LGPL v2.1 or later, see the file COPYING.LIB in this tarball. + + .text + .global _memchr + .type _memchr,function +! D0Ar6 src +! D0Ar2 c +! D1Ar3 n +_memchr: + CMP D1Ar3, #0 + BEQ $Lexit_fail + !! convert c to unsigned char + AND D0Ar2,D0Ar2,#0xff + MOV D0Ar6, D1Ar1 + MOV D1Ar5, D0Ar6 + !! test alignment + AND D1Ar5, D1Ar5, #7 + CMP D1Ar5, #0 + BNZ $Lunaligned_loop + !! length must be greater than or equal to 8 for aligned loop + CMP D1Ar3, #8 + BGE $Laligned_setup +$Lunaligned_loop: + !! get 1 char from s + GETB D0Re0, [D0Ar6++] + !! increase alignment counter + ADD D1Ar5, D1Ar5, #1 + !! decrement n + SUB D1Ar3, D1Ar3, #1 + !! exit if we have a match + CMP D0Re0, D0Ar2 + BZ $Lexit_success1 + !! exit if we have hit the end of the string + CMP D1Ar3, #0 + BZ $Lexit_fail + !! fall through if the buffer is aligned now + CMP D1Ar5, #8 + BNE $Lunaligned_loop + !! fall through if there is more than 8 bytes left + CMP D1Ar3, #8 + BLT $Lunaligned_loop +$Laligned_setup: + !! fill the c into 4 bytes + MOV D0Ar4, D0Ar2 + LSL D0Ar4, D0Ar4, #8 + ADD D0Ar4, D0Ar4, D0Ar2 + LSL D0Ar4, D0Ar4, #8 + ADD D0Ar4, D0Ar4, D0Ar2 + LSL D0Ar4, D0Ar4, #8 + ADD D0Ar4, D0Ar4, D0Ar2 + !! divide n by 8 + MOV D1Ar5, D1Ar3 + LSR D1Ar5, D1Ar5, #3 +$Laligned_loop: + !! get 8 chars from s + GETL D0Re0, D1Re0, [D0Ar6++] + !! decrement loop counter + SUB D1Ar5, D1Ar5, #1 + !! test first 4 chars + XOR D0Re0, D0Re0, D0Ar4 + !! test second 4 chars + MOV D0Ar2, D1Re0 + XOR D1Re0, D0Ar2, D0Ar4 + !! check for matches in the first 4 chars + MOV D0Ar2, D0Re0 + ADDT D0Re0, D0Re0, #HI(0xfefefeff) + ADD D0Re0, D0Re0, #LO(0xfefefeff) + XOR D0Ar2, D0Ar2, #-1 + AND D0Re0, D0Re0, D0Ar2 + ANDMT D0Re0, D0Re0, #HI(0x80808080) + ANDMB D0Re0, D0Re0, #LO(0x80808080) + CMP D0Re0, #0 + BNZ $Lmatch_word1 + !! check for matches in the second 4 chars + MOV D1Ar1, D1Re0 + ADDT D1Re0, D1Re0, #HI(0xfefefeff) + ADD D1Re0, D1Re0, #LO(0xfefefeff) + XOR D1Ar1, D1Ar1, #-1 + AND D1Re0, D1Re0, D1Ar1 + ANDMT D1Re0, D1Re0, #HI(0x80808080) + ANDMB D1Re0, D1Re0, #LO(0x80808080) + CMP D1Re0, #0 + BNZ $Lmatch_word2 + !! check if we have reached the end of the buffer + CMP D1Ar5, #0 + BNE $Laligned_loop + !! exit if there are no chars left to check + AND D1Ar3, D1Ar3, #7 + CMP D1Ar3, #0 + BZ $Lexit_fail + !! recover c + AND D0Ar2, D0Ar4, #0xff +$Lbyte_loop: + !! get 1 char from s + GETB D0Re0, [D0Ar6++] + !! decrement n + SUB D1Ar3, D1Ar3, #1 + !! exit if we have a match + CMP D0Re0, D0Ar2 + BZ $Lexit_success1 + !! fall through if we have run out of chars + CMP D1Ar3, #0 + BNE $Lbyte_loop + +$Lexit_fail: + MOV D0Re0, #0 + B $Lend + +$Lmatch_word1: + !! move the match word into D1Re0 + MOV D1Re0, D0Re0 + !! roll back the buffer pointer by 4 chars + SUB D0Ar6, D0Ar6, #4 +$Lmatch_word2: + !! roll back the buffer pointer by 4 chars + SUB D0Ar6, D0Ar6, #4 + !! exit if lowest byte is 0 + MOV D1Ar1, D1Re0 + AND D1Ar1, D1Ar1, #0xff + CMP D1Ar1, #0 + BNE $Lexit_success2 + !! advance buffer pointer to the next char + ADD D0Ar6, D0Ar6, #1 + !! shift in the next lowest byte + LSR D1Re0, D1Re0, #8 + !! exit if lowest byte is 0 + MOV D1Ar1, D1Re0 + AND D1Ar1, D1Ar1, #0xff + CMP D1Ar1, #0 + BNE $Lexit_success2 + !! advance buffer pointer to the next char + ADD D0Ar6, D0Ar6, #1 + !! shift in the next lowest byte + LSR D1Re0, D1Re0, #8 + !! exit if lowest byte is 0 + MOV D1Ar1, D1Re0 + AND D1Ar1, D1Ar1, #0xff + CMP D1Ar1, #0 + BNE $Lexit_success2 + !! the match must be in the last byte, exit + ADD D0Ar6, D0Ar6, #1 + B $Lexit_success2 + +$Lexit_success1: + SUB D0Ar6, D0Ar6, #1 +$Lexit_success2: + !! return the buffer pointer + MOV D0Re0, D0Ar6 +$Lend: + MOV PC, D1RtP + + .size _memchr,.-_memchr + +libc_hidden_def(memchr) |