/*************************************************************************** * __________ __ ___. * 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. * ****************************************************************************/ .section .icode,"ax",@progbits .align 2 .global _memcpy .type _memcpy,@function /* Copies bytes of data in memory from to * 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 / temporary * r1 - bit mask for rounding to long bounds / 2nd data * r2 - first long bound (only if >= 12 bytes) * r3 - last long bound (-4) (only if >= 12 bytes) * r4 - current dest address * r5 - current source address * r6 - source end address * r7 - stored dest start address * * The instruction order below 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: add r5,r6 /* r6 = source_end */ mov r4,r7 /* store for returning */ add #-8,r4 /* adjust for early increments (max. 2 longs) */ mov r6,r0 add #-12,r0 /* r0 = r6 - 12; don't go below 12 here! */ cmp/hs r5,r0 /* >= 12 bytes to copy? */ bf .start_b2 /* no, jump into byte loop */ mov #-4,r1 /* r1 = 0xFFFFFFFC */ mov r5,r2 add #3,r2 and r1,r2 /* r2 = first source long bound */ mov r6,r3 add #-4,r3 /* end offset for copying 2 longs per pass */ bra .start_b1 /* jump into leading byte loop */ and r1,r3 /* r3 = last source long bound - 4 */ /* leading byte loop: copies 0..3 bytes */ .align 2 .loop_b1: mov.b @r5+,r0 /* load byte & increment source addr */ add #1,r4 /* increment dest addr */ mov.b r0,@(7,r4) /* store byte */ .start_b1: cmp/hi r5,r2 /* 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 */ mov r4,r0 tst #3,r0 /* dest now also at long bound? */ bt .loop2_l /* yes, do long copy */ tst #1,r0 /* dest now at least at word bound? */ bt .start4_w /* yes, do word copy */ /* main loop for byte aligned destination (fast) */ /* copies 1 long per pass */ add #4,r3 /* reset end offset */ add #-1,r4 /* adjust to word alignment for word write+ */ .loop4_b: mov.l @r5+,r0 /* load a long & increment source addr */ add #4,r4 /* increment dest addr */ mov.b r0,@(8,r4) /* store low byte */ shlr8 r0 /* get middle 2 bytes */ mov.w r0,@(6,r4) /* store as word+ */ shlr16 r0 /* get upper byte */ mov.b r0,@(5,r4) /* and store */ cmp/hi r5,r3 /* runs r5 up to last long bound */ bt .loop4_b bra .start_b2 /* jump to trailing byte loop */ add #1,r4 /* readjust */ /* main loop for word aligned destination (faster) */ /* copies 2 longs per pass, utilizing fast page mode */ .start4_w: add #-2,r4 /* adjust to long alignment for long write+ */ .loop4_w: mov.l @r5+,r1 /* load first long & increment source addr */ add #8,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,@(8,r4) /* store low word of second long */ xtrct r1,r0 /* extract low word of first long & high word of second long */ mov.l r0,@(4,r4) /* and store as long+ */ swap.w r1,r0 /* get high word of first long */ mov.w r0,@(2,r4) /* and store it */ bt .loop4_w add #2,r4 /* readjust destination */ add #4,r3 /* reset end offset */ 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 */ /* main loop for long aligned destination (fastest) */ /* copies 2 longs per pass, utilizing fast page mode */ .loop2_l: mov.l @r5+,r1 /* load first long & increment source addr */ add #8,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.l r1,@r4 /* store first long */ mov.l r0,@(4,r4) /* store second long; NOT ALIGNED - no speed loss here! */ bt .loop2_l add #4,r3 /* reset end offset */ 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 */ /* trailing byte loop: copies 0..3 bytes (or all for < 12 in total) */ .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