Module Name: src
Committed By: matt
Date: Tue Jan 8 13:21:06 UTC 2013
Modified Files:
src/common/lib/libc/arch/arm/string: strcpy.S strlen.S
Log Message:
Depending on _STANDALONE include the "naive" version or the normal arm version.
To generate a diff of this commit:
cvs rdiff -u -r1.2 -r1.3 src/common/lib/libc/arch/arm/string/strcpy.S
cvs rdiff -u -r1.1 -r1.2 src/common/lib/libc/arch/arm/string/strlen.S
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/common/lib/libc/arch/arm/string/strcpy.S
diff -u src/common/lib/libc/arch/arm/string/strcpy.S:1.2 src/common/lib/libc/arch/arm/string/strcpy.S:1.3
--- src/common/lib/libc/arch/arm/string/strcpy.S:1.2 Wed Jan 2 15:38:03 2013
+++ src/common/lib/libc/arch/arm/string/strcpy.S Tue Jan 8 13:21:05 2013
@@ -1,527 +1,7 @@
-/*-
- * Copyright (c) 2013 The NetBSD Foundation, Inc.
- * All rights reserved.
- *
- * This code is derived from software contributed to The NetBSD Foundation
- * by Matt Thomas of 3am Software Foundry.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
- * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
- * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
- * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
+/* $NetBSD: strcpy.S,v 1.3 2013/01/08 13:21:05 matt Exp $ */
-#include <machine/asm.h>
-
-RCSID("$NetBSD: strcpy.S,v 1.2 2013/01/02 15:38:03 matt Exp $")
-
-#ifdef STRLCPY
-#ifdef _LIBC
-WEAK_ALIAS(strlcpy, _strlcpy)
-#endif
-#define FUNCNAME strlcpy
-#elif defined(STRNCPY)
-#define FUNCNAME strncpy
-#else
-#define FUNCNAME strcpy
-#endif
-
-#ifdef _LIBC
-#include "namespace.h"
-#endif
-
-#ifdef __ARMEL__
-#define lslo lsr /* shift to lower address */
-#define lshi lsl /* shift to higher address */
-#define BYTE0 0x000000ff
-#define BYTE1 0x0000ff00
-#define BYTE2 0x00ff0000
-#define BYTE3 0xff000000
-#else
-#define lslo lsl /* shift to lower address */
-#define lshi lsr /* shift to higher address */
-#define BYTE0 0xff000000
-#define BYTE1 0x00ff0000
-#define BYTE2 0x0000ff00
-#define BYTE3 0x000000ff
-#endif
-
-/*
- * On armv6 and later, to quickly determine if a word contains a NUL (0) byte,
- * we add 254 to each byte using the UQADD8 (unsigned saturating add 8)
- * instruction. For every non-NUL byte, the result for that byte will become
- * 255. For NUL, it will be 254. When we complement the result of all 4 adds,
- * if the result is non-0 then we must have encountered a NUL.
- *
- * For earlier architecture, we just use tst on all 4 bytes. There are other
- * algorithms to detect NULs but they take longer and use more instructions.
- */
-
-/*
- * char *strcpy(char *dst, const char *src);
- * char *strncpy(char *dst, const char *src, size_t len);
- * size_t strlcpy(char *dst, const char *src, size_t len);
- */
-
- .text
-ENTRY(FUNCNAME)
-#if defined(STRLCPY)
- cmp r2, #1 /* is length 1 or less? */
- bhi 1f /* no, do normal */
- moveq r3, #0 /* = 1? load NUL */
- streqb r3, [r0] /* = 1? write NUL to dst */
- mov r0, r1 /* move src to r0 */
- b PLT_SYM(_C_LABEL(strlen)) /* and tailcall strlen */
-1:
- sub r2, r2, #1 /* leave one byte for NUL */
-#endif
-#if defined(STRNCPY)
- cmp r2, #0 /* 0 length? */
- RETc(eq) /* yes, just return */
-#endif
- push {r4-r9} /* save some registers */
-#ifdef _ARM_ARCH_6
-#ifdef _ARM_ARCH_7
- movw r7, #0xfefe /* magic constant; 254 in each byte */
-#else
- mov r7, #0xfe /* put 254 in low byte */
- orr r7, r7, r7, lsl #8 /* move to next byte */
-#endif
- orr r7, r7, r7, lsl #16 /* move to next halfword */
-#endif
-
-#if defined(STRLCPY)
- add r6, r1, #1 /* save for return (deal with NUL) */
-#else
- mov r6, r0 /* save for return */
-#endif
-
-.Ldst_align:
- tst r0, #3 /* check for dst alignment */
- beq .Ldst_aligned /* ok, proceed to next check */
- ldrb r5, [r1], #1 /* load a byte */
-#if defined(STRNCPY)
- subs r2, r2, #1 /* subtract out from count */
- bmi .Ldst_full /* zero? the dst has no more room */
-#endif
- strb r5, [r0], #1 /* store a byte */
- teq r5, #0 /* was it a NUL? */
- beq .Lend_of_string /* yes, we are done */
-#if defined(STRLCPY)
- subs r2, r2, #1 /* subtract one from count */
- streqb r2, [r0], #1 /* zero? write trailing NUL */
- beq .Ldst_full /* zero? the dst has no more room */
-#endif
- b .Ldst_align /* loop around for next byte */
-.Ldst_aligned:
- tst r1, #3 /* get the misalignment of src */
- bne .Lincongruent /* !=? incongruent (slower) */
-
- /* =? congruent (faster) */
-
-.Lcongruent:
-#if defined(STRLCPY)
- add r6, r6, #3 /* compensate for word post-inc */
-#endif
- b .Lcongruent_mainloop_load
-.Lcongruent_mainloop:
-#if defined(STRLCPY) || defined(STRNCPY)
- subs r2, r2, #4 /* subtract 4 from the count */
- bmi .Lno_more_room
-#endif
- str r5, [r0], #4 /* store word into dst */
-#if defined(STRLCPY)
- beq .Lno_more_room /* count is 0? no room in dst */
-#endif
-#if defined(STRNCPY)
- beq .Ldst_full_word_aligned /* count is 0? no room in dst */
-#endif
-.Lcongruent_mainloop_load:
- ldr r5, [r1], #4 /* load word from source */
-#if defined(_ARM_ARCH_6)
- uqadd8 r3, r5, r7 /* magic happens here */
- mvns r3, r3 /* is the complemented result 0? */
- beq .Lcongruent_mainloop /* yes, no NULs, do it again */
-#else
- tst r5, #BYTE0 /* does byte 0 contain a NUL? */
- tstne r5, #BYTE1 /* no, does byte 1 contain a NUL? */
- tstne r5, #BYTE2 /* no, does byte 2 contain a NUL? */
- tstne r5, #BYTE3 /* no, does byte 3 contain a NUL? */
- bne .Lcongruent_mainloop /* yes, no NULs, do it again */
-#endif
-#if defined(STRLCPY) && 0
- sub r1, r1, #3 /* back up src pointer */
-#endif
-#if defined(_ARM_ARCH_6)
-#ifdef __ARMEL__
- rev r3, r3 /* CLZ needs BE data */
-#endif
- clz r3, r3 /* count leading zeros */
-#else
- mov r3, #0 /* assume NUL is in byte 0 */
- tst r5, #BYTE0 /* is NUL in byte 2? */
- beq .Lcongruent_last_bytes /* yes, done searching. */
- mov r3, #8 /* assume NUL is in byte 1 */
- tst r5, #BYTE1 /* is NUL in byte 2? */
- beq .Lcongruent_last_bytes /* yes, done searching. */
- mov r3, #16 /* assume NUL is in byte 2 */
- tst r5, #BYTE2 /* is NUL in byte 2? */
-#if !defined(STRLCPY)
- beq .Lcongruent_last_bytes /* yes, done searching. */
- mov r3, #24 /* NUL must be in byte 3 */
-#else
- movne r3, #24 /* no, then NUL is in byte 3 */
-#endif
-#endif /* _ARM_ARCH_6 */
-#if defined(STRLCPY)
-.Lcongruent_last_bytes:
-#endif
-#if defined(STRLCPY)
- add r1, r1, r3, lsr #3 /* position to point at NUL + 4 */
-#endif
- b .Llast_bytes /* store the last bytes */
-
-
-.Lincongruent:
- /*
- * At this point dst is word aligned by src is not. Read bytes
- * from src until it is read aligned.
- */
- and r3, r1, #3 /* extract misalignment */
- mov r9, r3, lsl #3 /* calculate discard shift */
- rsb r8, r9, #32 /* calculate insertion shift */
-#if defined(STRLCPY)
- add r6, r6, #3 /* compensate for word post-inc */
-#endif
- bic r1, r1, #3 /* word align src */
- ldr r5, [r1], #4 /* load word frm src */
- mov r4, r5, lslo r9 /* discard lo bytes from src */
- tst r4, #BYTE0 /* does byte 0 contain a NUL? */
-#if defined(STRNCPY)
- beq .Lend_of_string /* yes, zero fill rest of string */
-#else
- moveq r3, r9 /* yes, set offset */
- beq .Lincongruent_end_of_string /* yes, deal with the last bytes */
-#endif
- /*
- * To make our test for NULs below do not generate false positives,
- * fill the bytes in the word we don't want to match with all 1s.
- */
- mvn r3, #0 /* create a mask */
- mov r3, r3, lslo r8 /* zero out byte being kept */
- orr r3, r3, r5 /* merge src and mask */
-#ifdef _ARM_ARCH_6
- uqadd8 r3, r3, r7 /* NUL detection magic happens */
- mvns r3, r3 /* is the complemented result 0? */
- beq .Lincongruent_mainloop_load /* yes, no NUL encountered! */
-#ifdef __ARMEL__
- rev r3, r3 /* CLZ wants BE input */
-#endif
- clz r3, r3 /* count leading zeros */
-#else
- /*
- * We already tested for byte 0 above so we don't need to it again.
- */
- mov r3, #24 /* assume NUL is in byte 3 */
- tst r5, #BYTE1 /* did we find a NUL in byte 1? */
- subeq r3, r3, #8 /* yes, decremnt byte position */
- tstne r5, #BYTE2 /* no, did we find a NUL in byte 2? */
- subeq r3, r3, #8 /* yes, decremnt byte position */
- tstne r5, #BYTE3 /* no, did we find a NUL in byte 3? */
- bne .Lincongruent_mainloop_load /* no, no NUL encountered! */
-#endif
- mov r5, r4 /* discard already dealt with bytes */
-.Lincongruent_end_of_string:
-#if defined(STRLCPY)
- add r1, r1, r3, lsr #3 /* then add offset to NUL */
-#endif
- sub r3, r3, r9 /* adjust NUL offset */
- b .Llast_bytes /* NUL encountered! finish up */
-
-#if defined(STRLCPY) || defined(STRNCPY)
-.Lincongruent_no_more_room:
- mov r5, r4 /* move data to be stored to r5 */
- b .Lno_more_room /* fill remaining space */
-#endif /* STRLCPY || STRNCPY */
-
- /*
- * At this point both dst and src are word aligned and r4 contains
- * partial contents from src.
- */
-.Lincongruent_mainloop:
- orr r4, r4, r5, lshi r8 /* put new src data into dst word */
-#if defined(STRLCPY) || defined(STRNCPY)
- subs r2, r2, #4 /* subtract 4 from count */
- bmi .Lincongruent_no_more_room /* count < 0? dst will be full */
-#endif
- str r4, [r0], #4 /* store word in dst */
-#if defined(STRLCPY)
- beq .Lno_more_room /* space left is 0? stop copy */
-#endif
-#if defined(STRNCPY)
- beq .Ldst_full_word_aligned /* space left is 0? stop copy */
-#endif
- mov r4, r5, lslo r9 /* move rest of src into dst word */
-.Lincongruent_mainloop_load:
- ldr r5, [r1], #4 /* read src */
-#ifdef _ARM_ARCH_6
- uqadd8 r3, r5, r7 /* magic happens here */
- mvns r3, r3 /* is the complemented result 0? */
- beq .Lincongruent_mainloop /* yes, no NUL encountered! */
- /*
- * fall into this since we encountered a NULL. At this point we have
- * from 1-5 bytes (excluding trailing NUL) to write.
- */
-#ifdef __ARMEL__
- rev r3, r3 /* CLZ works on BE data */
-#endif
- clz r3, r3 /* count leading zeroes */
-#else
- tst r5, #BYTE0 /* does byte 0 contain a NUL? */
- tstne r5, #BYTE1 /* no, does byte 1 contain a NUL? */
- tstne r5, #BYTE2 /* no, does byte 2 contain a NUL? */
- tstne r5, #BYTE3 /* no, does byte 3 contain a NUL? */
- bne .Lincongruent_mainloop /* no, no NUL encountered! */
- /*
- * fall into this since we encountered a NULL. At this point we have
- * from 1-5 bytes (excluding trailing NUL) to write.
- */
- mov r3, #0 /* assume a NUL is in byte 0 */
- tst r5, #BYTE0 /* is there a NUL in byte 0? */
- beq 1f /* yes, found a NUL! */
- mov r3, #8 /* assume a NUL is in byte 1 */
- tst r5, #BYTE1 /* is there a NUL in byte 0? */
- beq 1f /* yes, found a NUL! */
- tst r5, #BYTE2 /* is there a NUL in byte 2? */
- moveq r3, #16 /* yes, mark its position */
- movne r3, #24 /* no, it must be in byte 3 */
-1:
-#endif
- orr r4, r4, r5, lshi r8 /* merge new and old src words */
-#if defined(STRLCPY)
- add r1, r1, r3, lsr #3 /* adjust src to point to NUL */
-#endif
- add r3, r3, r8 /* add remainder bytes worth */
- cmp r3, #32 /* do we have at least one word to write? */
- movlt r5, r4 /* no, move source bytes to expected reg */
- blt .Llast_bytes /* no, deal with them */
-#if defined(STRLCPY)
- subs r2, r2, #4 /* subtract 4 from count */
- bpl 1f /* we have space for at least 4 */
- /*
- * Since the space just went minus, we don't have enough room to
- * write all 4 bytes. In fact, the most we can write is 3 so just
- * just lie and say we have 3 bytes to write and discard the rest.
- */
- add r2, r2, #4 /* add 4 back */
- mov r3, #24 /* say we have 3 bytes */
- mov r5, r4 /* discard the bytes we can't store */
- b .Llast_bytes /* and treat this as our last word */
-1:
-#elif defined(STRNCPY)
- subs r2, r2, #4 /* subtract 4 from count */
- bmi .Lincongruent_no_more_room /* count < 0? dst will be full */
-#endif
- str r4, [r0], #4 /* store dst word */
-#if defined(STRNCPY)
- beq .Ldst_full_word_aligned /* space left is 0? stop copy */
-#endif
-#if defined(STRLCPY)
- bne 1f /* we still have space remaining */
- strb r2, [r0] /* write final NUL */
- b .Lend_of_string /* we are done */
-1:
-#endif
- /*
- * Subtract the 32 bits just written from the number of bits left
- * to write. If 0 bits are left and not doing strncpy, just write
- * the trailing NUL and be done.
- */
- subs r3, r3, #32 /* we wrote one word */
-#if !defined(STRNCPY)
- bne 1f /* no more data? */
- strb r3, [r0] /* write final NUL */
- b .Lend_of_string /* we are done */
-1:
-#endif
- /*
- * At this point after writing 4 bytes, we have 0 or 1 bytes left to
- * write (excluding the trailing NUL).
- */
- mov r5, r5, lslo r9 /* get remainder of src */
-
- /* fall into .Llast_bytes */
-
-#if !defined(STRLCPY)
-.Lcongruent_last_bytes:
-#endif
-.Llast_bytes:
- /*
- * r5 contains the last word and is in host byte order.
- * r3 contains number of bits left to copy (0..31).
- * r1 should point to the NUL + 4.
- */
- bics ip, r3, #7 /* truncate bits, is result 0? */
-#if !defined(STRNCPY)
- bne 1f /* no, have to write some bytes */
- strb ip, [r0] /* yes, write trailing NUL */
- b .Lend_of_string /* yes, and we are the end */
-1:
-#endif
-#if defined(STRLCPY) || defined(STRNCPY)
- cmp r2, ip, lsr #3 /* is there enough room? */
- movlt ip, r2, lsl #3 /* no, only fill remaining space */
-#endif
- mvn r3, #0 /* create a mask */
- mov r3, r3, lshi ip /* clear leading bytes */
- bic r5, r5, r3 /* clear trailing bytes */
-#if defined(STRNCPY)
- cmp r2, #4 /* room for 4 bytes? */
- movge ip, #32 /* yes, we will write 4 bytes */
- bge 2f /* yes, and go do it */
- mvn r3, #0 /* create a mask (again) */
- mov ip, r2, lsl #3 /* remaining space bytes -> bits */
- mov r3, r3, lshi ip /* clear remaining bytes */
-#elif defined(STRLCPY)
- cmp r2, #3 /* do we have room for 3 bytes & NUL? */
- bge 2f /* yes, just clear out dst */
- mov r3, r3, lshi #8 /* mask out trailing NUL */
-#else
- cmp ip, #24 /* are we writing 3 bytes & a NUL? */
- bge 2f /* yes, just overwrite dst */
- mov r3, r3, lshi #8 /* mask out trailing NUL */
-#endif /* !STRNCPY */
- ldr r4, [r0] /* fetch dst word */
- and r4, r4, r3 /* preserve trailing bytes */
- orr r5, r5, r4 /* merge dst with src */
-2: str r5, [r0], #4 /* store last word */
-#if defined(STRNCPY)
- subs r2, r2, ip, lsr #3 /* subtract bytes cleared from count */
- beq .Ldst_full_word_aligned
-#endif
- b .Lend_of_string
-
-#if defined(STRLCPY) || defined(STRNCPY)
-.Lno_more_room:
-#if defined(STRLCPY)
- cmp r2, #-1 /* tried to write 3 bytes? */
- blt 1f /* less, partial word write */
- cmp r2, #0 /* no space left? */
- streqb r2, [r0] /* write the final NUL */
- bicne r5, r5, #BYTE3 /* clear trailing NUL */
- strne r5, [r0] /* write last word */
- b .Ldst_full_word_aligned /* the dst buffer is full */
-1:
-#endif /* STRLCPY */
- add r2, r2, #4 /* restore remaining space */
- ldr r4, [r0] /* load dst */
- mvn r3, #0 /* create a mask */
- mov r2, r2, lsl #3 /* bytes -> bits */
- mov r3, r3, lshi r2 /* clear leading bytes */
- bic r5, r5, r3 /* clear trailing bytes from src */
-#if defined(STRLCPY)
- mov r3, r3, lshi #8 /* mask out trailing NUL */
-#endif /* STRLCPY */
- and r4, r4, r3 /* preserve trailing bytes in dst */
- orr r4, r4, r5 /* merge src with dst */
- str r4, [r0], #4 /* write last word */
- b .Ldst_full_word_aligned
-#endif /* STRLCPY || STRNCPY */
-
-#if defined(STRLCPY)
- /*
- * Destination was filled (and NUL terminated).
- * All that's left is count the number of bytes left in src.
- */
-.Ldst_full:
-1: tst r1, #3 /* dst word aligned? */
- beq 2f /* yes, so do it word by word */
- ldrb r5, [r1], #1 /* load next byte */
- teq r5, #0 /* is it a NUL? */
- bne 1b /* no, check alignment */
- b .Lend_of_string /* and return */
-2: add r6, r6, #3 /* compensate for post-inc */
-.Ldst_full_word_aligned:
-3: ldr r5, [r1], #4 /* load word from src */
-#ifdef _ARM_ARCH_6
- uqadd8 r5, r5, r7 /* perform NUL magic */
- mvns r5, r5 /* complement all 0s? */
- beq 3b /* yes, no NUL so get next word */
-#else
- tst r5, #BYTE0 /* does byte 0 contain a NUL? */
- tstne r5, #BYTE1 /* no, does byte 1 contain a NUL? */
- tstne r5, #BYTE2 /* no, does byte 2 contain a NUL? */
- tstne r5, #BYTE3 /* no, does byte 3 contain a NUL? */
- bne 3b /* no, no NUL encountered! */
-#endif
-#ifdef _ARM_ARCH_6
-#ifdef __ARMEL__
- rev r5, r5 /* CLZ needs BE data */
-#endif
- clz r5, r5 /* count leading zeros */
- add r1, r1, r5, lsr #3 /* add offset to NUL to src pointer */
-#else
- tst r5, #BYTE0 /* is there a NUL in byte 0? */
- beq 4f /* yes, don't check any further */
- add r1, r1, #1 /* no, advance src pointer by 1 */
- tst r5, #BYTE1 /* is there a NUL in byte 1? */
- beq 4f /* yes, don't check any further */
- add r1, r1, #1 /* no, advance src pointer by 1 */
- tst r5, #BYTE2 /* is there a NUL in byte 2? */
- addne r1, r1, #1 /* no, there must be in byte 3 */
-4:
-#endif /* _ARM_ARCH_6 */
-.Lend_of_string:
- sub r0, r1, r6 /* subtract start from finish */
- pop {r4-r9} /* restore registers */
- RET
-#elif defined(STRNCPY)
-.Lend_of_string:
- teq r2, #0 /* any bytes left to zero? */
- beq 3f /* no, just return. */
- mov r1, #0 /* yes, prepare to zero */
- cmp r2, #16 /* some, but not a lot? */
- ble 1f
- mov r4, lr /* preserve lr */
- bl PLT_SYM(_C_LABEL(memset)) /* yes, and let memset do it */
- mov lr, r4 /* restore lr */
- b 3f /* return */
-1: add ip, r0, r2 /* calculate stopping point */
-2: strb r1, [r0], #1 /* clear a byte */
- cmp r0, ip /* done? */
- blt 2b /* no, clear next byte */
-3: mov r0, r6 /* restore dst pointer */
- pop {r4-r9} /* restore registers */
- RET
-.Ldst_full:
-.Ldst_full_word_aligned:
- /*
- * Destination was filled (but not NUL terminated).
- * All that's left is return the start of dst
- */
- mov r0, r6 /* restore dst pointer */
- pop {r4-r9} /* restore registers */
- RET
+#ifdef _STANDALONE
+#include "strcpy_naive.S"
#else
-.Lend_of_string:
- mov r0, r6 /* restore dst pointer */
- pop {r4-r9} /* restore registers */
- RET
+#include "strcpy_arm.S"
#endif
-END(FUNCNAME)
Index: src/common/lib/libc/arch/arm/string/strlen.S
diff -u src/common/lib/libc/arch/arm/string/strlen.S:1.1 src/common/lib/libc/arch/arm/string/strlen.S:1.2
--- src/common/lib/libc/arch/arm/string/strlen.S:1.1 Wed Jan 2 15:24:21 2013
+++ src/common/lib/libc/arch/arm/string/strlen.S Tue Jan 8 13:21:05 2013
@@ -1,121 +1,7 @@
-/*-
- * Copyright (c) 2012 The NetBSD Foundation, Inc.
- * All rights reserved.
- *
- * This code is derived from software contributed to The NetBSD Foundation
- * by Matt Thomas of 3am Software Foundry.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
- * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
- * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
- * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
+/* $NetBSD: strlen.S,v 1.2 2013/01/08 13:21:05 matt Exp $ */
-#include <machine/asm.h>
-
-RCSID("$NetBSD: strlen.S,v 1.1 2013/01/02 15:24:21 matt Exp $")
-
-#ifdef __ARMEL__
-#define BYTE0 0x000000ff
-#define BYTE1 0x0000ff00
-#define BYTE2 0x00ff0000
-#define BYTE3 0xff000000
-#else
-#define BYTE0 0xff000000
-#define BYTE1 0x00ff0000
-#define BYTE2 0x0000ff00
-#define BYTE3 0x000000ff
-#endif
-
- .text
-ENTRY(strlen)
- add ip, r0, #4 /* for the final post-inc */
-1: tst r0, #3 /* test for word alignment */
- beq .Lpre_main_loop /* finally word aligned */
- ldrb r3, [r0], #1 /* load a byte */
- teq r3, #0 /* is it 0? */
- bne 1b /* no, try next byte */
- sub ip, ip, #3 /* subtract (4 - the NUL) */
- sub r0, r0, ip /* subtract start */
- RET /* return */
-.Lpre_main_loop:
-#if defined(_ARM_ARCH_6)
-#if defined(_ARM_ARCH_7)
- movw r1, #0xfefe /* magic constant; 254 in each byte */
+#ifdef _STANDALONE
+#include "strlen_naive.S"
#else
- mov r1, #0xfe /* put 254 in low byte */
- orr r1, r1, r1, lsl #8 /* move to next byte */
+#include "strlen_arm.S"
#endif
- orr r1, r1, r1, lsl #16 /* move to next halfword */
-#endif /* _ARM_ARCH_6 */
-.Lmain_loop:
- ldr r3, [r0], #4 /* load next word */
-#if defined(_ARM_ARCH_6)
- /*
- * Add 254 to each byte using the UQADD8 (unsigned saturating add 8)
- * instruction. For every non-NUL byte, the result for that byte will
- * become 255. For NUL, it will be 254. When we complement the
- * result, if the result is non-0 then we must have encountered a NUL.
- */
- uqadd8 r3, r3, r1 /* magic happens here */
- mvns r3, r3 /* is the complemented result non-0? */
- beq .Lmain_loop /* no, then we encountered no NULs */
-#else
- /*
- * No fancy shortcuts so just test each byte lane for a NUL.
- * (other tests for NULs in a word take more instructions/cycles).
- */
- tst r3, #BYTE0 /* is this byte 0? */
- tstne r3, #BYTE1 /* no, is this byte 0? */
- tstne r3, #BYTE2 /* no, is this byte 0? */
- tstne r3, #BYTE3 /* no, is this byte 0? */
- bne .Lmain_loop /* no, then get next word */
-#endif
-#if defined(_ARM_ARCH_6)
- /*
- * We encountered a NUL. Find out where by doing a CLZ and then
- * shifting right by 3. That will be the number of non-NUL bytes.
- */
-#ifdef __ARMEL__
- rev r3, r3 /* we want this in BE for the CLZ */
-#endif
- clz r3, r3 /* count how many leading zeros */
- add r0, r0, r3, lsr #3 /* divide that by 8 and add to count */
-#else
- /*
- * We encountered a NUL.
- */
- tst r3, #BYTE0 /* 1st byte was NUL? */
- beq 1f /* yes, done adding */
- add r0, r0, #1 /* we have one more non-NUL byte */
- tst r3, #BYTE1 /* 2nd byte was NUL? */
- beq 1f /* yes, done adding */
- add r0, r0, #1 /* we have one more non-NUL byte */
- tst r3, #BYTE2 /* 3rd byte was NUL? */
- addne r0, r0, #1 /* no, we have one more non-NUL byte */
-1:
-#endif /* _ARM_ARCH_6 */
- /*
- * r0 now points to 4 past the NUL due to the post-inc. Subtract the
- * start of the string (which also has 4 added to it to compensate for
- * the post-inc.
- */
- sub r0, r0, ip /* subtract start to get length */
- RET
-END(strlen)
