/* $NetBSD: memcpy.S,v 1.3 1997/11/22 03:27:12 mark Exp $ */ /*- * Copyright (c) 1997 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Neil A. Carson and Mark Brinicombe * * 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * 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. */ /* This was modified by Jay Monkman to * save and restore r12. This is necessary for RTEMS. */ /* #include */ .globl memcpy memcpy: stmfd sp!, {r0, r12, lr} bl _memcpy ldmfd sp!, {r0, r12, pc} .globl memove memmove: stmfd sp!, {r0, r12, lr} bl _memcpy ldmfd sp!, {r0, r12, pc} /* * This is one fun bit of code ... * Some easy listening music is suggested while trying to understand this * code e.g. Iron Maiden * * For anyone attempting to understand it : * * The core code is implemented here with simple stubs for memcpy() * memmove() and bcopy(). * * All local labels are prefixed with Lmemcpy_ * Following the prefix a label starting f is used in the forward copy code * while a label using b is used in the backwards copy code * The source and destination addresses determine whether a forward or * backward copy is performed. * Separate bits of code are used to deal with the following situations * for both the forward and backwards copy. * unaligned source address * unaligned destination address * Separate copy routines are used to produce an optimised result for each * of these cases. * The copy code will use LDM/STM instructions to copy up to 32 bytes at * a time where possible. * * Note: r12 (aka ip) can be trashed during the function along with * r0-r3 although r0-r2 have defined uses i.e. src, dest, len through out. * Additional registers are preserved prior to use i.e. r4, r5 & lr * * Apologies for the state of the comments;-) */ _memcpy: /* Determine copy direction */ cmp r1, r0 bcc Lmemcpy_backwards moveq r0, #0 /* Quick abort for len=0 */ moveq pc, lr stmdb sp!, {r0, lr} /* memcpy() returns dest addr */ subs r2, r2, #4 blt Lmemcpy_fl4 /* less than 4 bytes */ ands r12, r0, #3 bne Lmemcpy_fdestul /* oh unaligned destination addr */ ands r12, r1, #3 bne Lmemcpy_fsrcul /* oh unaligned source addr */ Lmemcpy_ft8: /* We have aligned source and destination */ subs r2, r2, #8 blt Lmemcpy_fl12 /* less than 12 bytes (4 from above) */ subs r2, r2, #0x14 blt Lmemcpy_fl32 /* less than 32 bytes (12 from above) */ stmdb sp!, {r4} /* borrow r4 */ /* blat 32 bytes at a time */ /* XXX for really big copies perhaps we should use more registers */ Lmemcpy_floop32: ldmia r1!, {r3, r4, r12, lr} stmia r0!, {r3, r4, r12, lr} ldmia r1!, {r3, r4, r12, lr} stmia r0!, {r3, r4, r12, lr} subs r2, r2, #0x20 bge Lmemcpy_floop32 cmn r2, #0x10 ldmgeia r1!, {r3, r4, r12, lr} /* blat a remaining 16 bytes */ stmgeia r0!, {r3, r4, r12, lr} subge r2, r2, #0x10 ldmia sp!, {r4} /* return r4 */ Lmemcpy_fl32: adds r2, r2, #0x14 /* blat 12 bytes at a time */ Lmemcpy_floop12: ldmgeia r1!, {r3, r12, lr} stmgeia r0!, {r3, r12, lr} subges r2, r2, #0x0c bge Lmemcpy_floop12 Lmemcpy_fl12: adds r2, r2, #8 blt Lmemcpy_fl4 subs r2, r2, #4 ldrlt r3, [r1], #4 strlt r3, [r0], #4 ldmgeia r1!, {r3, r12} stmgeia r0!, {r3, r12} subge r2, r2, #4 Lmemcpy_fl4: /* less than 4 bytes to go */ adds r2, r2, #4 ldmeqia sp!, {r0, pc} /* done */ /* copy the crud byte at a time */ cmp r2, #2 ldrb r3, [r1], #1 strb r3, [r0], #1 ldrgeb r3, [r1], #1 strgeb r3, [r0], #1 ldrgtb r3, [r1], #1 strgtb r3, [r0], #1 ldmia sp!, {r0, pc} /* erg - unaligned destination */ Lmemcpy_fdestul: rsb r12, r12, #4 cmp r12, #2 /* align destination with byte copies */ ldrb r3, [r1], #1 strb r3, [r0], #1 ldrgeb r3, [r1], #1 strgeb r3, [r0], #1 ldrgtb r3, [r1], #1 strgtb r3, [r0], #1 subs r2, r2, r12 blt Lmemcpy_fl4 /* less the 4 bytes */ ands r12, r1, #3 beq Lmemcpy_ft8 /* we have an aligned source */ /* erg - unaligned source */ /* This is where it gets nasty ... */ Lmemcpy_fsrcul: bic r1, r1, #3 ldr lr, [r1], #4 cmp r12, #2 bgt Lmemcpy_fsrcul3 beq Lmemcpy_fsrcul2 cmp r2, #0x0c blt Lmemcpy_fsrcul1loop4 sub r2, r2, #0x0c stmdb sp!, {r4, r5} Lmemcpy_fsrcul1loop16: mov r3, lr, lsr #8 ldmia r1!, {r4, r5, r12, lr} orr r3, r3, r4, lsl #24 mov r4, r4, lsr #8 orr r4, r4, r5, lsl #24 mov r5, r5, lsr #8 orr r5, r5, r12, lsl #24 mov r12, r12, lsr #8 orr r12, r12, lr, lsl #24 stmia r0!, {r3-r5, r12} subs r2, r2, #0x10 bge Lmemcpy_fsrcul1loop16 ldmia sp!, {r4, r5} adds r2, r2, #0x0c blt Lmemcpy_fsrcul1l4 Lmemcpy_fsrcul1loop4: mov r12, lr, lsr #8 ldr lr, [r1], #4 orr r12, r12, lr, lsl #24 str r12, [r0], #4 subs r2, r2, #4 bge Lmemcpy_fsrcul1loop4 Lmemcpy_fsrcul1l4: sub r1, r1, #3 b Lmemcpy_fl4 Lmemcpy_fsrcul2: cmp r2, #0x0c blt Lmemcpy_fsrcul2loop4 sub r2, r2, #0x0c stmdb sp!, {r4, r5} Lmemcpy_fsrcul2loop16: mov r3, lr, lsr #16 ldmia r1!, {r4, r5, r12, lr} orr r3, r3, r4, lsl #16 mov r4, r4, lsr #16 orr r4, r4, r5, lsl #16 mov r5, r5, lsr #16 orr r5, r5, r12, lsl #16 mov r12, r12, lsr #16 orr r12, r12, lr, lsl #16 stmia r0!, {r3-r5, r12} subs r2, r2, #0x10 bge Lmemcpy_fsrcul2loop16 ldmia sp!, {r4, r5} adds r2, r2, #0x0c blt Lmemcpy_fsrcul2l4 Lmemcpy_fsrcul2loop4: mov r12, lr, lsr #16 ldr lr, [r1], #4 orr r12, r12, lr, lsl #16 str r12, [r0], #4 subs r2, r2, #4 bge Lmemcpy_fsrcul2loop4 Lmemcpy_fsrcul2l4: sub r1, r1, #2 b Lmemcpy_fl4 Lmemcpy_fsrcul3: cmp r2, #0x0c blt Lmemcpy_fsrcul3loop4 sub r2, r2, #0x0c stmdb sp!, {r4, r5} Lmemcpy_fsrcul3loop16: mov r3, lr, lsr #24 ldmia r1!, {r4, r5, r12, lr} orr r3, r3, r4, lsl #8 mov r4, r4, lsr #24 orr r4, r4, r5, lsl #8 mov r5, r5, lsr #24 orr r5, r5, r12, lsl #8 mov r12, r12, lsr #24 orr r12, r12, lr, lsl #8 stmia r0!, {r3-r5, r12} subs r2, r2, #0x10 bge Lmemcpy_fsrcul3loop16 ldmia sp!, {r4, r5} adds r2, r2, #0x0c blt Lmemcpy_fsrcul3l4 Lmemcpy_fsrcul3loop4: mov r12, lr, lsr #24 ldr lr, [r1], #4 orr r12, r12, lr, lsl #8 str r12, [r0], #4 subs r2, r2, #4 bge Lmemcpy_fsrcul3loop4 Lmemcpy_fsrcul3l4: sub r1, r1, #1 b Lmemcpy_fl4 Lmemcpy_backwards: add r1, r1, r2 add r0, r0, r2 subs r2, r2, #4 blt Lmemcpy_bl4 /* less than 4 bytes */ ands r12, r0, #3 bne Lmemcpy_bdestul /* oh unaligned destination addr */ ands r12, r1, #3 bne Lmemcpy_bsrcul /* oh unaligned source addr */ Lmemcpy_bt8: /* We have aligned source and destination */ subs r2, r2, #8 blt Lmemcpy_bl12 /* less than 12 bytes (4 from above) */ stmdb sp!, {r4, lr} subs r2, r2, #0x14 /* less than 32 bytes (12 from above) */ blt Lmemcpy_bl32 /* blat 32 bytes at a time */ /* XXX for really big copies perhaps we should use more registers */ Lmemcpy_bloop32: ldmdb r1!, {r3, r4, r12, lr} stmdb r0!, {r3, r4, r12, lr} ldmdb r1!, {r3, r4, r12, lr} stmdb r0!, {r3, r4, r12, lr} subs r2, r2, #0x20 bge Lmemcpy_bloop32 Lmemcpy_bl32: cmn r2, #0x10 ldmgedb r1!, {r3, r4, r12, lr} /* blat a remaining 16 bytes */ stmgedb r0!, {r3, r4, r12, lr} subge r2, r2, #0x10 adds r2, r2, #0x14 ldmgedb r1!, {r3, r12, lr} /* blat a remaining 12 bytes */ stmgedb r0!, {r3, r12, lr} subge r2, r2, #0x0c ldmia sp!, {r4, lr} Lmemcpy_bl12: adds r2, r2, #8 blt Lmemcpy_bl4 subs r2, r2, #4 ldrlt r3, [r1, #-4]! strlt r3, [r0, #-4]! ldmgedb r1!, {r3, r12} stmgedb r0!, {r3, r12} subge r2, r2, #4 Lmemcpy_bl4: /* less than 4 bytes to go */ adds r2, r2, #4 moveq pc, lr /* done */ /* copy the crud byte at a time */ cmp r2, #2 ldrb r3, [r1, #-1]! strb r3, [r0, #-1]! ldrgeb r3, [r1, #-1]! strgeb r3, [r0, #-1]! ldrgtb r3, [r1, #-1]! strgtb r3, [r0, #-1]! mov pc, lr /* erg - unaligned destination */ Lmemcpy_bdestul: cmp r12, #2 /* align destination with byte copies */ ldrb r3, [r1, #-1]! strb r3, [r0, #-1]! ldrgeb r3, [r1, #-1]! strgeb r3, [r0, #-1]! ldrgtb r3, [r1, #-1]! strgtb r3, [r0, #-1]! subs r2, r2, r12 blt Lmemcpy_bl4 /* less than 4 bytes to go */ ands r12, r1, #3 beq Lmemcpy_bt8 /* we have an aligned source */ /* erg - unaligned source */ /* This is where it gets nasty ... */ Lmemcpy_bsrcul: bic r1, r1, #3 ldr r3, [r1, #0] cmp r12, #2 blt Lmemcpy_bsrcul1 beq Lmemcpy_bsrcul2 cmp r2, #0x0c blt Lmemcpy_bsrcul3loop4 sub r2, r2, #0x0c stmdb sp!, {r4, r5, lr} Lmemcpy_bsrcul3loop16: mov lr, r3, lsl #8 ldmdb r1!, {r3-r5, r12} orr lr, lr, r12, lsr #24 mov r12, r12, lsl #8 orr r12, r12, r5, lsr #24 mov r5, r5, lsl #8 orr r5, r5, r4, lsr #24 mov r4, r4, lsl #8 orr r4, r4, r3, lsr #24 stmdb r0!, {r4, r5, r12, lr} subs r2, r2, #0x10 bge Lmemcpy_bsrcul3loop16 ldmia sp!, {r4, r5, lr} adds r2, r2, #0x0c blt Lmemcpy_bsrcul3l4 Lmemcpy_bsrcul3loop4: mov r12, r3, lsl #8 ldr r3, [r1, #-4]! orr r12, r12, r3, lsr #24 str r12, [r0, #-4]! subs r2, r2, #4 bge Lmemcpy_bsrcul3loop4 Lmemcpy_bsrcul3l4: add r1, r1, #3 b Lmemcpy_bl4 Lmemcpy_bsrcul2: cmp r2, #0x0c blt Lmemcpy_bsrcul2loop4 sub r2, r2, #0x0c stmdb sp!, {r4, r5, lr} Lmemcpy_bsrcul2loop16: mov lr, r3, lsl #16 ldmdb r1!, {r3-r5, r12} orr lr, lr, r12, lsr #16 mov r12, r12, lsl #16 orr r12, r12, r5, lsr #16 mov r5, r5, lsl #16 orr r5, r5, r4, lsr #16 mov r4, r4, lsl #16 orr r4, r4, r3, lsr #16 stmdb r0!, {r4, r5, r12, lr} subs r2, r2, #0x10 bge Lmemcpy_bsrcul2loop16 ldmia sp!, {r4, r5, lr} adds r2, r2, #0x0c blt Lmemcpy_bsrcul2l4 Lmemcpy_bsrcul2loop4: mov r12, r3, lsl #16 ldr r3, [r1, #-4]! orr r12, r12, r3, lsr #16 str r12, [r0, #-4]! subs r2, r2, #4 bge Lmemcpy_bsrcul2loop4 Lmemcpy_bsrcul2l4: add r1, r1, #2 b Lmemcpy_bl4 Lmemcpy_bsrcul1: cmp r2, #0x0c blt Lmemcpy_bsrcul1loop4 sub r2, r2, #0x0c stmdb sp!, {r4, r5, lr} Lmemcpy_bsrcul1loop32: mov lr, r3, lsl #24 ldmdb r1!, {r3-r5, r12} orr lr, lr, r12, lsr #8 mov r12, r12, lsl #24 orr r12, r12, r5, lsr #8 mov r5, r5, lsl #24 orr r5, r5, r4, lsr #8 mov r4, r4, lsl #24 orr r4, r4, r3, lsr #8 stmdb r0!, {r4, r5, r12, lr} subs r2, r2, #0x10 bge Lmemcpy_bsrcul1loop32 ldmia sp!, {r4, r5, lr} adds r2, r2, #0x0c blt Lmemcpy_bsrcul1l4 Lmemcpy_bsrcul1loop4: mov r12, r3, lsl #24 ldr r3, [r1, #-4]! orr r12, r12, r3, lsr #8 str r12, [r0, #-4]! subs r2, r2, #4 bge Lmemcpy_bsrcul1loop4 Lmemcpy_bsrcul1l4: add r1, r1, #1 b Lmemcpy_bl4