417 lines
10 KiB
ArmAsm
417 lines
10 KiB
ArmAsm
/*
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* Copyright (c) 1987, 1997, 2006,
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* Vrije Universiteit, Amsterdam, The Netherlands.
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* All rights reserved. Redistribution and use of the MINIX 3 operating system
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* in source and binary forms, with or without modification, are permitted
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* provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the Vrije Universiteit nor the names of the software
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* authors or contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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* * Any deviations from these conditions require written permission from the
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* copyright holder in advance
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS, AUTHORS, AND
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
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* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL PRENTICE HALL OR ANY
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* AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Contributions by Neil A. Carson and Mark Brinicombe.
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*/
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#include <machine/asm.h>
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#if !defined(__minix)
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#if defined(__ARM_EABI__)
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STRONG_ALIAS(__aeabi_memcpy, memcpy)
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#endif
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#endif /* !defined(__minix) */
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/*
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* This is one fun bit of code ...
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* Some easy listening music is suggested while trying to understand this
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* code e.g. Iron Maiden
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*
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* For anyone attempting to understand it :
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*
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* The core code is implemented here with simple stubs for memcpy().
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*
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* All local labels are prefixed with Lmemcpy_
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* Following the prefix a label starting f is used in the forward copy code
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* while a label using b is used in the backwards copy code
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* The source and destination addresses determine whether a forward or
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* backward copy is performed.
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* Separate bits of code are used to deal with the following situations
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* for both the forward and backwards copy.
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* unaligned source address
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* unaligned destination address
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* Separate copy routines are used to produce an optimised result for each
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* of these cases.
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* The copy code will use LDM/STM instructions to copy up to 32 bytes at
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* a time where possible.
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*
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* Note: r12 (aka ip) can be trashed during the function along with
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* r0-r3 although r0-r2 have defined uses i.e. src, dest, len through out.
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* Additional registers are preserved prior to use i.e. r4, r5 & lr
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*
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* Apologies for the state of the comments ;-)
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*/
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/* MINIX spills r0, r4, r5 and lr so the stack can be cleaned after a
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* phys_copy fault. Other systems spill the minimum number of registers. */
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#if defined(__minix)
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/* LINTSTUB: Func: void *phys_copy(void *src, void *dst, size_t len) */
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ENTRY(phys_copy)
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/* switch the source and destination registers */
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eor r0, r1, r0 eor r1, r0, r1 eor r0, r1,
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r0
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#else
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/* LINTSTUB: Func: void *memcpy(void *dst, const void *src, size_t len) */
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ENTRY(memcpy)
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#endif
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/* save leaf functions having to store this away */
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#if defined(__minix)
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push{r0, r4, r5, lr} /* memcpy() returns dest addr */
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#else
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push{r0, lr} /* memcpy() returns dest addr */
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#endif
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subs r2,
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r2,
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# 4 blt.Lmemcpy_l4 /* less than 4 bytes */
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ands r12, r0,
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# 3 bne.Lmemcpy_destul /* oh unaligned destination addr */
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ands r12, r1,
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# 3 bne
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.Lmemcpy_srcul /* oh unaligned source addr */
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.Lmemcpy_t8 :
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/* We have aligned source and destination */
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subs r2,
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r2,
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# 8 blt.Lmemcpy_l12 /* less than 12 bytes (4 from above) */
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subs r2, r2,
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# 0x14 blt
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.Lmemcpy_l32 /* less than 32 bytes (12 from above) */
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#if !defined(__minix)
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push{r4} /* borrow r4 */
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#endif
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/* blat 32 bytes at a time */
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/* XXX for really big copies perhaps we should use more registers */
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.Lmemcpy_loop32 : ldmia r1 !,
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{r3, r4, r12, lr} stmia r0 !, {r3, r4, r12, lr} ldmia r1 !,
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{r3, r4, r12, lr} stmia r0 !, {r3, r4, r12, lr} subs r2, r2,
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# 0x20 bge.Lmemcpy_loop32
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cmn r2,
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# 0x10 ldmiage r1 !,
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{r3, r4, r12, lr} /* blat a remaining 16 bytes */
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stmiage r0 !,
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{r3, r4, r12, lr} subge r2, r2,
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# 0x10
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#if !defined(__minix)
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pop{r4} /* return r4 */
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#endif
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.Lmemcpy_l32 : adds r2,
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r2,
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# 0x14
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/* blat 12 bytes at a time */
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.Lmemcpy_loop12 : ldmiage r1 !, {r3, r12, lr} stmiage r0 !,
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{r3, r12, lr} subsge r2, r2,
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# 0x0c bge
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.Lmemcpy_loop12
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.Lmemcpy_l12 : adds r2,
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r2,
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# 8 blt.Lmemcpy_l4
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subs r2, r2, #4 ldrlt r3, [r1], #4 strlt r3, [r0], #4 ldmiage r1 !,
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{r3, r12} stmiage r0 !, {r3, r12} subge r2, r2,
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# 4
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.Lmemcpy_l4 :
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/* less than 4 bytes to go */
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adds r2,
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r2,
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# 4
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#if defined(__minix)
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popeq{r0, r4, r5} moveq r0,
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# 0 popeq{pc }
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#else
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#ifdef __APCS_26_
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ldmiaeq sp !,
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{r0, pc} ^ /* done */
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#else
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popeq{r0, pc} /* done */
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#endif
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#endif
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/* copy the crud byte at a time */
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cmp r2,
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# 2 ldrb r3, [r1], #1 strb r3, [r0], #1 ldrbge r3, [r1], #1 strbge r3, [r0],
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# 1 ldrbgt r3, [r1], #1 strbgt r3, [r0],
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# 1
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#if defined(__minix)
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pop{r0, r4, r5} mov r0,
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# 0 pop{pc }
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#else
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pop{r0, pc}
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#endif
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/* erg - unaligned destination */
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.Lmemcpy_destul : rsb r12, r12, #4 cmp r12,
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# 2
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/* align destination with byte copies */
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ldrb r3, [r1], #1 strb r3, [r0], #1 ldrbge r3, [r1], #1 strbge r3, [r0],
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# 1 ldrbgt r3, [r1], #1 strbgt r3, [r0], #1 subs r2, r2,
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r12 blt.Lmemcpy_l4 /* less the 4 bytes */
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ands r12,
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r1,
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# 3 beq
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.Lmemcpy_t8 /* we have an aligned source */
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/* erg - unaligned source */
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/* This is where it gets nasty ... */
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.Lmemcpy_srcul : bic r1,
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r1, #3 ldr lr, [r1], #4 cmp r12,
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# 2 bgt.Lmemcpy_srcul3 beq.Lmemcpy_srcul2 cmp r2,
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# 0x0c blt.Lmemcpy_srcul1loop4 sub r2, r2,
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# 0x0c
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#if !defined(__minix)
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push{r4, r5}
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#endif
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.Lmemcpy_srcul1loop16 :
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#ifdef __ARMEB__
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mov r3,
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lr,
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lsl #8
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#else
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mov r3,
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lr,
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lsr #8
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#endif
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ldmia r1 !,
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{r4, r5, r12, lr}
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#ifdef __ARMEB__
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orr r3,
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r3, r4, lsr #24 mov r4, r4, lsl #8 orr r4, r4, r5, lsr #24 mov r5, r5,
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lsl #8 orr r5, r5, r12, lsr #24 mov r12, r12, lsl #8 orr r12, r12, lr,
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lsr #24
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#else
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orr r3,
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r3, r4, lsl #24 mov r4, r4, lsr #8 orr r4, r4, r5, lsl #24 mov r5, r5,
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lsr #8 orr r5, r5, r12, lsl #24 mov r12, r12, lsr #8 orr r12, r12, lr,
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lsl #24
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#endif
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stmia r0 !,
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{r3 - r5, r12} subs r2, r2,
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# 0x10 bge.Lmemcpy_srcul1loop16
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#if !defined(__minix)
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pop{r4, r5}
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#endif
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adds r2,
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r2,
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# 0x0c blt
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.Lmemcpy_srcul1l4
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.Lmemcpy_srcul1loop4 :
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#ifdef __ARMEB__
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mov r12,
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lr,
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lsl #8
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#else
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mov r12,
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lr,
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lsr #8
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#endif
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ldr lr,
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[r1],
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# 4
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#ifdef __ARMEB__
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orr r12, r12, lr,
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lsr #24
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#else
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orr r12,
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r12, lr,
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lsl #24
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#endif
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str r12,
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[r0], #4 subs r2, r2,
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# 4 bge
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.Lmemcpy_srcul1loop4
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.Lmemcpy_srcul1l4 : sub r1,
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r1,
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# 3 b.Lmemcpy_l4
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.Lmemcpy_srcul2 : cmp r2,
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# 0x0c blt.Lmemcpy_srcul2loop4 sub r2, r2,
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# 0x0c
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#if !defined(__minix)
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push{r4, r5}
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#endif
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.Lmemcpy_srcul2loop16 :
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#ifdef __ARMEB__
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mov r3,
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lr,
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lsl #16
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#else
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mov r3,
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lr,
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lsr #16
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#endif
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ldmia r1 !,
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{r4, r5, r12, lr}
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#ifdef __ARMEB__
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orr r3,
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r3, r4, lsr #16 mov r4, r4, lsl #16 orr r4, r4, r5, lsr #16 mov r5, r5,
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lsl #16 orr r5, r5, r12, lsr #16 mov r12, r12, lsl #16 orr r12, r12, lr,
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lsr #16
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#else
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orr r3,
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r3, r4, lsl #16 mov r4, r4, lsr #16 orr r4, r4, r5, lsl #16 mov r5, r5,
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lsr #16 orr r5, r5, r12, lsl #16 mov r12, r12, lsr #16 orr r12, r12, lr,
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lsl #16
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#endif
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stmia r0 !,
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{r3 - r5, r12} subs r2, r2,
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# 0x10 bge.Lmemcpy_srcul2loop16
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#if !defined(__minix)
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pop{r4, r5}
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#endif
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adds r2,
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r2,
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# 0x0c blt
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.Lmemcpy_srcul2l4
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.Lmemcpy_srcul2loop4 :
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#ifdef __ARMEB__
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mov r12,
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lr,
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lsl #16
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#else
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mov r12,
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lr,
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lsr #16
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#endif
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ldr lr,
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[r1],
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# 4
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#ifdef __ARMEB__
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orr r12, r12, lr,
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lsr #16
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#else
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orr r12,
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r12, lr,
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lsl #16
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#endif
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str r12,
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[r0], #4 subs r2, r2,
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# 4 bge
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.Lmemcpy_srcul2loop4
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.Lmemcpy_srcul2l4 : sub r1,
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r1,
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# 2 b.Lmemcpy_l4
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.Lmemcpy_srcul3 : cmp r2,
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# 0x0c blt.Lmemcpy_srcul3loop4 sub r2, r2,
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# 0x0c
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#if !defined(__minix)
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push{r4, r5}
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#endif
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.Lmemcpy_srcul3loop16 :
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#ifdef __ARMEB__
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mov r3,
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lr,
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lsl #24
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#else
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mov r3,
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lr,
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lsr #24
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#endif
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ldmia r1 !,
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{r4, r5, r12, lr}
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#ifdef __ARMEB__
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orr r3,
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r3, r4, lsr #8 mov r4, r4, lsl #24 orr r4, r4, r5, lsr #8 mov r5, r5,
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lsl #24 orr r5, r5, r12, lsr #8 mov r12, r12, lsl #24 orr r12, r12, lr,
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lsr #8
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#else
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orr r3,
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r3, r4, lsl #8 mov r4, r4, lsr #24 orr r4, r4, r5, lsl #8 mov r5, r5,
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lsr #24 orr r5, r5, r12, lsl #8 mov r12, r12, lsr #24 orr r12, r12, lr,
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lsl #8
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#endif
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stmia r0 !,
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{r3 - r5, r12} subs r2, r2,
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# 0x10 bge.Lmemcpy_srcul3loop16
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#if !defined(__minix)
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pop{r4, r5}
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#endif
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adds r2,
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r2,
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# 0x0c blt
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.Lmemcpy_srcul3l4
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.Lmemcpy_srcul3loop4 :
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#ifdef __ARMEB__
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mov r12,
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lr,
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lsl #24
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#else
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mov r12,
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lr,
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lsr #24
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#endif
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ldr lr,
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[r1],
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# 4
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#ifdef __ARMEB__
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orr r12, r12, lr,
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lsr #8
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#else
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orr r12,
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r12, lr,
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lsl #8
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#endif
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str r12,
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[r0], #4 subs r2, r2,
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# 4 bge
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.Lmemcpy_srcul3loop4
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.Lmemcpy_srcul3l4 : sub r1,
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r1,
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# 1 b.Lmemcpy_l4
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#if defined(__minix)
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LABEL(phys_copy_fault) /* kernel can send us here */
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pop{r0, r4, r5} pop{pc}
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LABEL(phys_copy_fault_in_kernel) /* kernel can send us here */
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pop{r0, r4, r5} mrc p15,
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0, r0, c6, c0,
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0 /* Read DFAR */
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pop{pc}
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#else
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END(memcpy)
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#endif
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