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-rwxr-xr-xfirmware/target/sh/memcpy-sh.S217
-rwxr-xr-xfirmware/target/sh/memmove-sh.S220
-rwxr-xr-xfirmware/target/sh/memset-sh.S107
-rwxr-xr-xfirmware/target/sh/strlen-sh.S94
4 files changed, 638 insertions, 0 deletions
diff --git a/firmware/target/sh/memcpy-sh.S b/firmware/target/sh/memcpy-sh.S
new file mode 100755
index 0000000000..0b5e086be9
--- /dev/null
+++ b/firmware/target/sh/memcpy-sh.S
@@ -0,0 +1,217 @@
+/***************************************************************************
+ * __________ __ ___.
+ * Open \______ \ ____ ____ | | _\_ |__ _______ ___
+ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
+ * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
+ * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
+ * \/ \/ \/ \/ \/
+ * $Id$
+ *
+ * Copyright (C) 2004-2005 by Jens Arnold
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "config.h"
+
+ .section .icode,"ax",@progbits
+
+ .align 2
+ .global _memcpy
+ .global ___memcpy_fwd_entry
+ .type _memcpy,@function
+
+/* Copies <length> bytes of data in memory from <source> to <dest>
+ * This version is optimized for speed
+ *
+ * arguments:
+ * r4 - destination address
+ * r5 - source address
+ * r6 - length
+ *
+ * return value:
+ * r0 - destination address (like ANSI version)
+ *
+ * register usage:
+ * r0 - data / scratch
+ * r1 - 2nd data / scratch
+ * r2 - scratch
+ * r3 - first long bound / adjusted end address (only if >= 11 bytes)
+ * r4 - current dest address
+ * r5 - current source address
+ * r6 - source end address
+ * r7 - stored dest start address
+ *
+ * The instruction order is devised in a way to utilize the pipelining
+ * of the SH1 to the max. The routine also tries to utilize fast page mode.
+ */
+
+_memcpy:
+ mov r4,r7 /* store dest for returning */
+___memcpy_fwd_entry:
+ add #-8,r4 /* offset for early increment (max. 2 longs) */
+ mov #11,r0
+ cmp/hs r0,r6 /* at least 11 bytes to copy? (ensures 2 aligned longs) */
+ add r5,r6 /* r6 = source_end */
+ bf .start_b2 /* no: jump directly to byte loop */
+
+ mov #3,r0
+ neg r5,r3
+ and r0,r3 /* r3 = (4 - align_offset) % 4 */
+ tst r3,r3 /* already aligned? */
+ bt .end_b1 /* yes: skip leading byte loop */
+
+ add r5,r3 /* r3 = first source long bound */
+
+ /* leading byte loop: copies 0..3 bytes */
+.loop_b1:
+ mov.b @r5+,r0 /* load byte & increment source addr */
+ add #1,r4 /* increment dest addr */
+ mov.b r0,@(7,r4) /* store byte */
+ cmp/hi r5,r3 /* runs r5 up to first long bound */
+ bt .loop_b1
+ /* now r5 is always at a long boundary */
+ /* -> memory reading is done in longs for all dest alignments */
+
+ /* selector for main copy loop */
+.end_b1:
+ mov #3,r1
+ and r4,r1 /* r1 = dest alignment offset */
+ mova .jmptab,r0
+ mov.b @(r0,r1),r1 /* select appropriate main loop */
+ add r0,r1
+ mov r6,r3 /* move end address to r3 */
+ jmp @r1 /* and jump to it */
+ add #-7,r3 /* adjust end addr for main loops doing 2 longs/pass */
+
+ /** main loops, copying 2 longs per pass to profit from fast page mode **/
+
+ /* long aligned destination (fastest) */
+ .align 2
+.loop_do0:
+ mov.l @r5+,r1 /* load first long & increment source addr */
+ add #16,r4 /* increment dest addr & account for decrementing stores */
+ mov.l @r5+,r0 /* load second long & increment source addr */
+ cmp/hi r5,r3 /* runs r5 up to last or second last long bound */
+ mov.l r0,@-r4 /* store second long */
+ mov.l r1,@-r4 /* store first long; NOT ALIGNED - no speed loss here! */
+ bt .loop_do0
+
+ add #4,r3 /* readjust end address */
+ cmp/hi r5,r3 /* one long left? */
+ bf .start_b2 /* no, jump to trailing byte loop */
+
+ mov.l @r5+,r0 /* load last long & increment source addr */
+ add #4,r4 /* increment dest addr */
+ bra .start_b2 /* jump to trailing byte loop */
+ mov.l r0,@(4,r4) /* store last long */
+
+ /* word aligned destination (long + 2) */
+ .align 2
+.loop_do2:
+ mov.l @r5+,r1 /* load first long & increment source addr */
+ add #16,r4 /* increment dest addr */
+ mov.l @r5+,r0 /* load second long & increment source addr */
+ cmp/hi r5,r3 /* runs r5 up to last or second last long bound */
+ mov.w r0,@-r4 /* store low word of second long */
+ xtrct r1,r0 /* extract low word of first long & high word of second long */
+ mov.l r0,@-r4 /* and store as long */
+ swap.w r1,r0 /* get high word of first long */
+ mov.w r0,@-r4 /* and store it */
+ bt .loop_do2
+
+ add #4,r3 /* readjust end address */
+ cmp/hi r5,r3 /* one long left? */
+ bf .start_b2 /* no, jump to trailing byte loop */
+
+ mov.l @r5+,r0 /* load last long & increment source addr */
+ add #4,r4 /* increment dest addr */
+ mov.w r0,@(6,r4) /* store low word */
+ shlr16 r0 /* get high word */
+ bra .start_b2 /* jump to trailing byte loop */
+ mov.w r0,@(4,r4) /* and store it */
+
+ /* jumptable for loop selector */
+ .align 2
+.jmptab:
+ .byte .loop_do0 - .jmptab /* placed in the middle because the SH1 */
+ .byte .loop_do1 - .jmptab /* loads bytes sign-extended. Otherwise */
+ .byte .loop_do2 - .jmptab /* the last loop would be out of reach */
+ .byte .loop_do3 - .jmptab /* of the offset range. */
+
+ /* byte aligned destination (long + 1) */
+ .align 2
+.loop_do1:
+ mov.l @r5+,r1 /* load first long & increment source addr */
+ add #16,r4 /* increment dest addr */
+ mov.l @r5+,r0 /* load second long & increment source addr */
+ cmp/hi r5,r3 /* runs r5 up to last or second last long bound */
+ mov.b r0,@-r4 /* store low byte of second long */
+ shlr8 r0 /* get upper 3 bytes */
+ mov r1,r2 /* copy first long */
+ shll16 r2 /* move low byte of first long all the way up, .. */
+ shll8 r2
+ or r2,r0 /* ..combine with the 3 bytes of second long.. */
+ mov.l r0,@-r4 /* ..and store as long */
+ shlr8 r1 /* get middle 2 bytes */
+ mov.w r1,@-r4 /* store as word */
+ shlr16 r1 /* get upper byte */
+ mov.b r1,@-r4 /* and store */
+ bt .loop_do1
+
+ add #4,r3 /* readjust end address */
+.last_do13:
+ cmp/hi r5,r3 /* one long left? */
+ bf .start_b2 /* no, jump to trailing byte loop */
+
+ mov.l @r5+,r0 /* load last long & increment source addr */
+ add #12,r4 /* increment dest addr */
+ mov.b r0,@-r4 /* store low byte */
+ shlr8 r0 /* get middle 2 bytes */
+ mov.w r0,@-r4 /* store as word */
+ shlr16 r0 /* get upper byte */
+ mov.b r0,@-r4 /* and store */
+ bra .start_b2 /* jump to trailing byte loop */
+ add #-4,r4 /* readjust destination */
+
+ /* byte aligned destination (long + 3) */
+ .align 2
+.loop_do3:
+ mov.l @r5+,r1 /* load first long & increment source addr */
+ add #16,r4 /* increment dest addr */
+ mov.l @r5+,r0 /* load second long & increment source addr */
+ mov r1,r2 /* copy first long */
+ mov.b r0,@-r4 /* store low byte of second long */
+ shlr8 r0 /* get middle 2 bytes */
+ mov.w r0,@-r4 /* store as word */
+ shlr16 r0 /* get upper byte */
+ shll8 r2 /* move lower 3 bytes of first long one up.. */
+ or r2,r0 /* ..combine with the 1 byte of second long.. */
+ mov.l r0,@-r4 /* ..and store as long */
+ shlr16 r1 /* get upper byte of first long.. */
+ shlr8 r1
+ cmp/hi r5,r3 /* runs r5 up to last or second last long bound */
+ mov.b r1,@-r4 /* ..and store */
+ bt .loop_do3
+
+ bra .last_do13 /* handle last longword: reuse routine for (long + 1) */
+ add #4,r3 /* readjust end address */
+
+ /* trailing byte loop: copies 0..3 bytes (or all for < 11 in total) */
+ .align 2
+.loop_b2:
+ mov.b @r5+,r0 /* load byte & increment source addr */
+ add #1,r4 /* increment dest addr */
+ mov.b r0,@(7,r4) /* store byte */
+.start_b2:
+ cmp/hi r5,r6 /* runs r5 up to end address */
+ bt .loop_b2
+
+ rts
+ mov r7,r0 /* return dest start address */
+.end:
+ .size _memcpy,.end-_memcpy
diff --git a/firmware/target/sh/memmove-sh.S b/firmware/target/sh/memmove-sh.S
new file mode 100755
index 0000000000..9ae9ae5fa2
--- /dev/null
+++ b/firmware/target/sh/memmove-sh.S
@@ -0,0 +1,220 @@
+/***************************************************************************
+ * __________ __ ___.
+ * Open \______ \ ____ ____ | | _\_ |__ _______ ___
+ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
+ * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
+ * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
+ * \/ \/ \/ \/ \/
+ * $Id$
+ *
+ * Copyright (C) 2006 by Jens Arnold
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "config.h"
+
+ .section .icode,"ax",@progbits
+
+ .align 2
+ .global _memmove
+ .type _memmove,@function
+
+/* Moves <length> bytes of data in memory from <source> to <dest>
+ * Regions may overlap.
+ * This version is optimized for speed, and needs the corresponding memcpy
+ * implementation for the forward copy branch.
+ *
+ * arguments:
+ * r4 - destination address
+ * r5 - source address
+ * r6 - length
+ *
+ * return value:
+ * r0 - destination address (like ANSI version)
+ *
+ * register usage:
+ * r0 - data / scratch
+ * r1 - 2nd data / scratch
+ * r2 - scratch
+ * r3 - last long bound / adjusted start address (only if >= 11 bytes)
+ * r4 - current dest address
+ * r5 - source start address
+ * r6 - current source address
+ *
+ * The instruction order is devised in a way to utilize the pipelining
+ * of the SH1 to the max. The routine also tries to utilize fast page mode.
+ */
+
+_memmove:
+ cmp/hi r4,r5 /* source > destination */
+ bf .backward /* no: backward copy */
+ mov.l .memcpy_fwd,r0
+ jmp @r0
+ mov r4,r7 /* store dest for returning */
+
+ .align 2
+.memcpy_fwd:
+ .long ___memcpy_fwd_entry
+
+.backward:
+ add r6,r4 /* r4 = destination end */
+ mov #11,r0
+ cmp/hs r0,r6 /* at least 11 bytes to copy? (ensures 2 aligned longs) */
+ add #-8,r5 /* adjust for late decrement (max. 2 longs) */
+ add r5,r6 /* r6 = source end - 8 */
+ bf .start_b2r /* no: jump directly to byte loop */
+
+ mov #-4,r3 /* r3 = 0xfffffffc */
+ and r6,r3 /* r3 = last source long bound */
+ cmp/hi r3,r6 /* already aligned? */
+ bf .end_b1r /* yes: skip leading byte loop */
+
+.loop_b1r:
+ mov.b @(7,r6),r0 /* load byte */
+ add #-1,r6 /* decrement source addr */
+ mov.b r0,@-r4 /* store byte */
+ cmp/hi r3,r6 /* runs r6 down to last long bound */
+ bt .loop_b1r
+
+.end_b1r:
+ mov #3,r1
+ and r4,r1 /* r1 = dest alignment offset */
+ mova .jmptab_r,r0
+ mov.b @(r0,r1),r1 /* select appropriate main loop.. */
+ add r0,r1
+ mov r5,r3 /* copy start adress to r3 */
+ jmp @r1 /* ..and jump to it */
+ add #7,r3 /* adjust end addr for main loops doing 2 longs/pass */
+
+ /** main loops, copying 2 longs per pass to profit from fast page mode **/
+
+ /* long aligned destination (fastest) */
+ .align 2
+.loop_do0r:
+ mov.l @r6,r1 /* load first long */
+ add #-8,r6 /* decrement source addr */
+ mov.l @(12,r6),r0 /* load second long */
+ cmp/hi r3,r6 /* runs r6 down to first or second long bound */
+ mov.l r0,@-r4 /* store second long */
+ mov.l r1,@-r4 /* store first long; NOT ALIGNED - no speed loss here! */
+ bt .loop_do0r
+
+ add #-4,r3 /* readjust end address */
+ cmp/hi r3,r6 /* first long left? */
+ bf .start_b2r /* no, jump to trailing byte loop */
+
+ mov.l @(4,r6),r0 /* load first long */
+ add #-4,r6 /* decrement source addr */
+ bra .start_b2r /* jump to trailing byte loop */
+ mov.l r0,@-r4 /* store first long */
+
+ /* word aligned destination (long + 2) */
+ .align 2
+.loop_do2r:
+ mov.l @r6,r1 /* load first long */
+ add #-8,r6 /* decrement source addr */
+ mov.l @(12,r6),r0 /* load second long */
+ cmp/hi r3,r6 /* runs r6 down to first or second long bound */
+ mov.w r0,@-r4 /* store low word of second long */
+ xtrct r1,r0 /* extract low word of first long & high word of second long */
+ mov.l r0,@-r4 /* and store as long */
+ shlr16 r1 /* get high word of first long */
+ mov.w r1,@-r4 /* and store it */
+ bt .loop_do2r
+
+ add #-4,r3 /* readjust end address */
+ cmp/hi r3,r6 /* first long left? */
+ bf .start_b2r /* no, jump to trailing byte loop */
+
+ mov.l @(4,r6),r0 /* load first long & decrement source addr */
+ add #-4,r6 /* decrement source addr */
+ mov.w r0,@-r4 /* store low word */
+ shlr16 r0 /* get high word */
+ bra .start_b2r /* jump to trailing byte loop */
+ mov.w r0,@-r4 /* and store it */
+
+ /* jumptable for loop selector */
+ .align 2
+.jmptab_r:
+ .byte .loop_do0r - .jmptab_r /* placed in the middle because the SH1 */
+ .byte .loop_do1r - .jmptab_r /* loads bytes sign-extended. Otherwise */
+ .byte .loop_do2r - .jmptab_r /* the last loop would be out of reach */
+ .byte .loop_do3r - .jmptab_r /* of the offset range. */
+
+ /* byte aligned destination (long + 1) */
+ .align 2
+.loop_do1r:
+ mov.l @r6,r1 /* load first long */
+ add #-8,r6 /* decrement source addr */
+ mov.l @(12,r6),r0 /* load second long */
+ cmp/hi r3,r6 /* runs r6 down to first or second long bound */
+ mov.b r0,@-r4 /* store low byte of second long */
+ shlr8 r0 /* get upper 3 bytes */
+ mov r1,r2 /* copy first long */
+ shll16 r2 /* move low byte of first long all the way up, .. */
+ shll8 r2
+ or r2,r0 /* ..combine with the 3 bytes of second long.. */
+ mov.l r0,@-r4 /* ..and store as long */
+ shlr8 r1 /* get middle 2 bytes */
+ mov.w r1,@-r4 /* store as word */
+ shlr16 r1 /* get upper byte */
+ mov.b r1,@-r4 /* and store */
+ bt .loop_do1r
+
+ add #-4,r3 /* readjust end address */
+.last_do13r:
+ cmp/hi r3,r6 /* first long left? */
+ bf .start_b2r /* no, jump to trailing byte loop */
+
+ nop /* alignment */
+ mov.l @(4,r6),r0 /* load first long */
+ add #-4,r6 /* decrement source addr */
+ mov.b r0,@-r4 /* store low byte */
+ shlr8 r0 /* get middle 2 bytes */
+ mov.w r0,@-r4 /* store as word */
+ shlr16 r0 /* get upper byte */
+ bra .start_b2r /* jump to trailing byte loop */
+ mov.b r0,@-r4 /* and store */
+
+ /* byte aligned destination (long + 3) */
+ .align 2
+.loop_do3r:
+ mov.l @r6,r1 /* load first long */
+ add #-8,r6 /* decrement source addr */
+ mov.l @(12,r6),r0 /* load second long */
+ mov r1,r2 /* copy first long */
+ mov.b r0,@-r4 /* store low byte of second long */
+ shlr8 r0 /* get middle 2 bytes */
+ mov.w r0,@-r4 /* store as word */
+ shlr16 r0 /* get upper byte */
+ shll8 r2 /* move lower 3 bytes of first long one up.. */
+ or r2,r0 /* ..combine with the 1 byte of second long.. */
+ mov.l r0,@-r4 /* ..and store as long */
+ shlr16 r1 /* get upper byte of first long */
+ shlr8 r1
+ cmp/hi r3,r6 /* runs r6 down to first or second long bound */
+ mov.b r1,@-r4 /* ..and store */
+ bt .loop_do3r
+
+ bra .last_do13r /* handle first longword: reuse routine for (long + 1) */
+ add #-4,r3 /* readjust end address */
+
+ /* trailing byte loop: copies 0..3 bytes (or all for < 11 in total) */
+ .align 2
+.loop_b2r:
+ mov.b @(7,r6),r0 /* load byte */
+ add #-1,r6 /* decrement source addr */
+ mov.b r0,@-r4 /* store byte */
+.start_b2r:
+ cmp/hi r5,r6 /* runs r6 down to start address */
+ bt .loop_b2r
+
+ rts
+ mov r4,r0 /* return dest start address */
+.end:
+ .size _memmove,.end-_memmove
diff --git a/firmware/target/sh/memset-sh.S b/firmware/target/sh/memset-sh.S
new file mode 100755
index 0000000000..9b96b93f27
--- /dev/null
+++ b/firmware/target/sh/memset-sh.S
@@ -0,0 +1,107 @@
+/***************************************************************************
+ * __________ __ ___.
+ * Open \______ \ ____ ____ | | _\_ |__ _______ ___
+ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
+ * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
+ * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
+ * \/ \/ \/ \/ \/
+ * $Id$
+ *
+ * Copyright (C) 2004 by Jens Arnold
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "config.h"
+
+ .section .icode,"ax",@progbits
+
+ .align 2
+ .global _memset
+ .type _memset,@function
+
+/* Fills a memory region with specified byte value
+ * This version is optimized for speed
+ *
+ * arguments:
+ * r4 - start address
+ * r5 - data
+ * r6 - length
+ *
+ * return value:
+ * r0 - start address (like ANSI version)
+ *
+ * register usage:
+ * r0 - temporary
+ * r1 - start address +11 for main loop
+ * r4 - start address
+ * r5 - data (spread to all 4 bytes when using long stores)
+ * r6 - current address (runs down from end to start)
+ *
+ * The instruction order below is devised in a way to utilize the pipelining
+ * of the SH1 to the max. The routine fills memory from end to start in
+ * order to utilize the auto-decrementing store instructions.
+ */
+
+_memset:
+ neg r4,r0
+ and #3,r0 /* r0 = (4 - align_offset) % 4 */
+ add #4,r0
+ cmp/hs r0,r6 /* at least one aligned longword to fill? */
+ add r4,r6 /* r6 = end_address */
+ bf .no_longs /* no, jump directly to byte loop */
+
+ extu.b r5,r5 /* start: spread data to all 4 bytes */
+ swap.b r5,r0
+ or r0,r5 /* data now in 2 lower bytes of r5 */
+ swap.w r5,r0
+ or r0,r5 /* data now in all 4 bytes of r5 */
+
+ mov r6,r0
+ tst #3,r0 /* r0 already long aligned? */
+ bt .end_b1 /* yes: skip loop */
+
+ /* leading byte loop: sets 0..3 bytes */
+.loop_b1:
+ mov.b r5,@-r0 /* store byte */
+ tst #3,r0 /* r0 long aligned? */
+ bf .loop_b1 /* runs r0 down until long aligned */
+
+ mov r0,r6 /* r6 = last long bound */
+ nop /* keep alignment */
+
+.end_b1:
+ mov r4,r1 /* r1 = start_address... */
+ add #11,r1 /* ... + 11, combined for rounding and offset */
+ xor r1,r0
+ tst #4,r0 /* bit 2 tells whether an even or odd number of */
+ bf .loop_odd /* longwords to set */
+
+ /* main loop: set 2 longs per pass */
+.loop_2l:
+ mov.l r5,@-r6 /* store first long */
+.loop_odd:
+ cmp/hi r1,r6 /* runs r6 down to first long bound */
+ mov.l r5,@-r6 /* store second long */
+ bt .loop_2l
+
+.no_longs:
+ cmp/hi r4,r6 /* any bytes left? */
+ bf .end_b2 /* no: skip loop */
+
+ /* trailing byte loop */
+.loop_b2:
+ mov.b r5,@-r6 /* store byte */
+ cmp/hi r4,r6 /* runs r6 down to the start address */
+ bt .loop_b2
+
+.end_b2:
+ rts
+ mov r4,r0 /* return start address */
+
+.end:
+ .size _memset,.end-_memset
diff --git a/firmware/target/sh/strlen-sh.S b/firmware/target/sh/strlen-sh.S
new file mode 100755
index 0000000000..34837605ac
--- /dev/null
+++ b/firmware/target/sh/strlen-sh.S
@@ -0,0 +1,94 @@
+/***************************************************************************
+ * __________ __ ___.
+ * Open \______ \ ____ ____ | | _\_ |__ _______ ___
+ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
+ * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
+ * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
+ * \/ \/ \/ \/ \/
+ * $Id$
+ *
+ * Copyright (C) 2005 by Jens Arnold
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "config.h"
+
+ .section .icode,"ax",@progbits
+
+ .align 2
+ .global _strlen
+ .type _strlen,@function
+
+/* Works out the length of a string
+ * This version is optimized for speed
+ *
+ * arguments:
+ * r4 - start address
+ *
+ * return value:
+ * r0 - string length
+ *
+ * register usage:
+ * r0 - current address
+ * r1 - current value (byte/long)
+ * r2 - mask for alignment / zero (for cmp/str)
+ * r4 - start address
+ *
+ */
+
+_strlen:
+ mov r4,r0 /* r0 = start address */
+ tst #3,r0 /* long aligned? */
+ bt .start_l /* yes, jump directly to the longword loop */
+
+ /* not long aligned: check the first 3 bytes */
+ mov.b @r0+,r1 /* fetch first byte */
+ tst r1,r1 /* byte == 0 ? */
+ bt .hitzero /* yes, string end found */
+ mov.b @r0+,r1 /* fetch second byte */
+ mov #3,r2 /* prepare mask: r2 = 0..00000011b */
+ tst r1,r1 /* byte == 0 ? */
+ bt .hitzero /* yes, string end found */
+ mov.b @r0+,r1 /* fetch third byte */
+ not r2,r2 /* prepare mask: r2 = 1..11111100b */
+ tst r1,r1 /* byte == 0 ? */
+ bt .hitzero /* yes, string end found */
+
+ /* not yet found, fall through into longword loop */
+ and r2,r0 /* align down to long bound */
+
+ /* main loop: check longwords */
+.start_l:
+ mov #0,r2 /* zero longword for cmp/str */
+.loop_l:
+ mov.l @r0+,r1 /* fetch long word */
+ cmp/str r1,r2 /* any zero byte within? */
+ bf .loop_l /* no, loop */
+ add #-4,r0 /* set address back to start of this longword */
+
+ /* the last longword contains the string end: figure out the byte */
+ mov.b @r0+,r1 /* fetch first byte */
+ tst r1,r1 /* byte == 0 ? */
+ bt .hitzero /* yes, string end found */
+ mov.b @r0+,r1 /* fetch second byte */
+ tst r1,r1 /* byte == 0 ? */
+ bt .hitzero /* yes, string end found */
+ mov.b @r0+,r1 /* fetch third byte */
+ tst r1,r1 /* byte == 0 ? */
+ bt .hitzero /* yes, string end found */
+ rts /* must be the fourth byte */
+ sub r4,r0 /* len = string_end - string_start */
+
+.hitzero:
+ add #-1,r0 /* undo address increment */
+ rts
+ sub r4,r0 /* len = string_end - string_start */
+
+.end:
+ .size _strlen,.end-_strlen
+