66f496cb88
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@18970 a1c6a512-1295-4272-9138-f99709370657
149 lines
4.3 KiB
ArmAsm
149 lines
4.3 KiB
ArmAsm
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2008 by Jens Arnold
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*
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* based on arm_nrv2e_d8.S -- ARM decompressor for NRV2E
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* Copyright (C) 1996-2008 Markus Franz Xaver Johannes Oberhumer
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* Copyright (C) 1996-2008 Laszlo Molnar
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* Copyright (C) 2000-2008 John F. Reiser
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#define src r4
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#define dst r5
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#define len r6 /* overlaps 'cnt' */
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#define cnt r6 /* overlaps 'len' while reading an offset */
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#define tmp r7
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#define off r0 /* must be r0 because of indexed addressing */
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#define bits r1
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#define bitmask r2
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#define wrnk r3 /* -0x500 -M2_MAX_OFFSET before "wrinkle" */
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#define GETBIT \
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tst bits, bitmask; \
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bf 1f; \
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bsr get1_n2e; \
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1: \
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shll bits /* using the delay slot on purpose */
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#define getnextb(reg) GETBIT; rotcl reg
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#define jnextb0 GETBIT; bf
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#define jnextb1 GETBIT; bt
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.section .icode,"ax",@progbits
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.align 2
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.global _ucl_nrv2e_decompress_8
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.type _ucl_nrv2e_decompress_8,@function
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/* src_len = ucl_nrv2e_decompress_8(const unsigned char *src,
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* unsigned char *dst,
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* unsigned long *dst_len)
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*/
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_ucl_nrv2e_decompress_8:
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sts.l pr, @-r15
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mov #-1, off ! off = -1 initial condition
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mov.l r6, @-r15
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mov #-5, wrnk
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mov.l r5, @-r15
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shll8 wrnk ! nrv2e -M2_MAX_OFFSET
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mov.l r4, @-r15
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mov #-1, bitmask
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shlr bitmask ! 0x7fffffff for testing before shifting
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bra top_n2e
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not bitmask, bits ! refill next time (MSB must be set)
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eof_n2e:
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mov.l @r15+, r0 ! r0 = orig_src
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mov.l @r15+, r1 ! r1 = orig_dst
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sub r0, src
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mov.l @r15+, r2 ! r2 = plen_dst
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sub r1, dst
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mov.l dst, @r2
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lds.l @r15+, pr
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rts
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mov src, r0
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lit_n2e:
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mov.b @src, tmp
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add #1, src ! Need to fill the pipeline latency anyway
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mov.b tmp, @dst
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add #1, dst
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top_n2e:
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jnextb1 lit_n2e
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bra getoff_n2e
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mov #1, cnt
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off_n2e:
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add #-1, cnt
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getnextb(cnt)
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getoff_n2e:
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getnextb(cnt)
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jnextb0 off_n2e
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mov #-4, tmp ! T=1 on entry, so this does
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addc cnt, tmp ! tmp = cnt - 3, T = (cnt >= 3)
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mov #0, len ! cnt and len share a reg!
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bf offprev_n2e ! cnt was 2
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mov.b @src+, off ! low 7+1 bits
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shll8 tmp
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extu.b off, off
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or tmp, off
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not off, off ! off = ~off
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tst off, off
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bt eof_n2e
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shar off
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bt lenlast_n2e
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bf lenmore_n2e ! always taken if the preceding bt isn't
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offprev_n2e:
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jnextb1 lenlast_n2e
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lenmore_n2e:
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mov #1, len
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jnextb1 lenlast_n2e
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len_n2e:
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getnextb(len)
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jnextb0 len_n2e
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bra gotlen_n2e
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mov #6-2, tmp
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get1_n2e: ! in: T bit set
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mov.b @src+, bits ! SH1 sign-extends on load
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rotcl bits ! LSB = T, T = MSB
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shll16 bits
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rts
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shll8 bits
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lenlast_n2e:
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getnextb(len) ! 0,1,2,3
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mov #2, tmp
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gotlen_n2e:
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cmp/gt off, wrnk ! too far away, so minimum match length is 3
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addc tmp, len
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copy_n2e:
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add #-1, len
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mov.b @(off,dst), tmp
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tst len, len
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mov.b tmp, @dst
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add #1, dst
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bf copy_n2e
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bt top_n2e ! always taken if the preceding bf isn't
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.size ucl_nrv2e_decompress_8, .-ucl_nrv2e_decompress_8
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