diff options
Diffstat (limited to 'private/crt32/string/mips/strcatm.s')
| -rw-r--r-- | private/crt32/string/mips/strcatm.s | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/private/crt32/string/mips/strcatm.s b/private/crt32/string/mips/strcatm.s new file mode 100644 index 000000000..0c22c47de --- /dev/null +++ b/private/crt32/string/mips/strcatm.s @@ -0,0 +1,98 @@ +/* ------------------------------------------------------------------ */ +/* | Copyright Unpublished, MIPS Computer Systems, Inc. All Rights | */ +/* | Reserved. This software contains proprietary and confidential | */ +/* | information of MIPS and its suppliers. Use, disclosure or | */ +/* | reproduction is prohibited without the prior express written | */ +/* | consent of MIPS. | */ +/* ------------------------------------------------------------------ */ +/* strcat.s 1.1 */ + +/* This function is an assembly-code replacement for the libc function + * strcat. + + * strcat and strcpy are very similar, but we waste about 40 words of + * code when both are used, so that they can be independently replaced. + + * There are one caveat to consider: this function is written in + * assembler code, and as such, cannot be merged using the U-code + * loader. */ + +/* Craig Hansen - 3-September-86 */ + +#include <kxmips.h> + +/* It turns out better to think of lwl/lwr and swl/swr as + smaller-vs-bigger address rather than left-vs-right. + Such a representation makes the code endian-independent. */ + +#define LWS lwr +#define LWB lwl +#define SWS swr +#define SWB swl + +.text + +LEAF_ENTRY(strcat) +.set noreorder + // a0/ destination + // a1/ source + move v0, a0 # a copy of destination address is returned +$findz: lb t0,0(a0) + nop + bne t0,0,$findz + add a0,1 + // go back over null byte + add a0,-1 + // start up first word + // adjust pointers so that a0 points to next word + // t7 = a1 adjusted by same amount minus one + // t0,t1,t2,t3 are filled with 4 consecutive bytes + // t4 is filled with the same 4 bytes in a single word + lb t0, 0(a1) + ori t5, a0, 3 # get an early start + beq t0, 0, $doch0 + sub t6, t5, a0 # number of char in 1st word of dest - 1 + lb t1, 1(a1) + add t7, a1, t6 # offset starting point for source string + beq t1, 0, $doch1 + nop + lb t2, 2(a1) + nop + beq t2, 0, $doch2 + LWS t4, 0(a1) # safe: always in same word as 0(a1) + lb t3, 3(a1) + LWB t4, 3(a1) # fill out word + beq t3, 0, $doch3 + SWS t4, 0(a0) # store entire or part word + addi a0, t5, 1-4 # adjust destination ptr + + // inner loop +1: lb t0, 1(t7) + addi t7, 4 + beq t0, 0, $doch0 + addi a0, 4 + lb t1, 1+1-4(t7) + nop + beq t1, 0, $doch1 + nop + lb t2, 2+1-4(t7) + nop + beq t2, 0, $doch2 + LWS t4, 0+1-4(t7) + lb t3, 3+1-4(t7) + LWB t4, 3+1-4(t7) + bne t3, 0, 1b + sw t4, 0(a0) + j ra + nop + + // store four bytes using swl/swr +$doch3: j ra + SWB t4, 3(a0) + // store up to three bytes, a byte at a time. +$doch2: sb t2, 2(a0) +$doch1: sb t1, 1(a0) +$doch0: j ra + sb t0, 0(a0) + +.end strcat |