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/* arm_nrv2e_d8.S -- ARM decompressor for NRV2E
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This file is part of the UPX executable compressor.
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Copyright (C) 1996-2004 Markus Franz Xaver Johannes Oberhumer
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Copyright (C) 1996-2004 Laszlo Molnar
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Copyright (C) 2000-2006 John F. Reiser
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UPX and the UCL library are free software; you can redistribute them
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and/or modify them under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; see the file COPYING.
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If not, write to the Free Software Foundation, Inc.,
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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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Markus F.X.J. Oberhumer Laszlo Molnar
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<mfx@users.sourceforge.net> <ml1050@users.sourceforge.net>
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<jreiser@users.sourceforge.net>
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#define SAFE 0 /* 1 for src+dst bounds checking: cost 40 bytes */
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#define len r1 /* overlaps 'cnt' */
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#define wrnk r6 /* 0x500 M2_MAX_OFFSET before "wrinkle" */
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#define cnt r1 /* overlaps 'len' while reading an offset */
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#define CHECK_SRC cmp src,srclim; bhs bad_src_n2e
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#define CHECK_DST cmp dst,dstlim; bhs bad_dst_n2e
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#define CHECK_SRC /*empty*/
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#define CHECK_DST /*empty*/
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#if 0 /*{ DEBUG only: check newly-decompressed against original dst */
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cmp wrnk,tmp; beq 0f; bkpt; \
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#define CHECK_BYTE /*empty*/
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/* "mov lr,pc; bxx ..." implements conditional subroutine call */
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#define GETBIT add bits,bits; mov lr,pc; beq get1_n2e
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#define getnextb(reg) GETBIT; adc reg,reg
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#define jnextb0 GETBIT; bcc
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#define jnextb1 GETBIT; bcs
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ucl_nrv2e_decompress_8: .globl ucl_nrv2e_decompress_8 @ ARM mode
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.type ucl_nrv2e_decompress_8, %function
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/* error = (*)(char const *src, int len_src, char *dst, int *plen_dst)
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Actual decompressed length is stored through plen_dst.
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For SAFE mode: at call, *plen_dst must be allowed length of output buffer.
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adr r12,1+thumb_nrv2e_d8; bx r12 @ enter THUMB mode
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push {r2,r3, r4,r5,r6,r7, lr}
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#define sp_DST0 0 /* stack offset of original dst */
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add srclim,len,src @ srclim= eof_src;
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ldr tmp,[r3] @ len_dst
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mov bits,#1; neg off,bits @ off= -1 initial condition
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lsl bits,#31 @ 1<<31; refill next time
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lsl wrnk,#8 @ 0x500 @ nrv2e M2_MAX_OFFSET
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bad_dst_n2e: # return value will be 2
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bad_src_n2e: # return value will be 1
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pop {r3,r4} @ r3= orig_dst; r4= plen_dst
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sub src,srclim @ 0 if actual src length equals expected length
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sub dst,r3 @ actual dst length
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pop {r4,r5,r6,r7 /*,pc*/}
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pop {r1}; bx r1 @ "pop {,pc}" fails return to ARM mode on ARMv4T
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get1_n2e: @ In: Carry set [from adding 0x80000000 (1<<31) to itself]
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ldrb bits,[src] @ zero-extend next byte
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adc bits,bits @ double and insert CarryIn as low bit
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lsl bits,#24 @ move to top byte, and set CarryOut from old bit 8
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mov pc,lr @ return, stay in current (THUMB) mode
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CHECK_SRC; ldrb tmp,[src]; add src,#1
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CHECK_DST; strb tmp,[dst]; add dst,#1
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mov cnt,#1; b getoff_n2e
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sub tmp,cnt,#3 @ set Carry
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mov len,#0 @ Carry unaffected
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blo offprev_n2e @ cnt was 2; tests Carry only
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CHECK_SRC; ldrb off,[src]; add src,#1 @ low 7+1 bits
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mvn off,off; beq eof_n2e @ off= ~off
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asr off,#1; bcs lenlast_n2e
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getnextb(len) @ 0,1,2,3
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gotlen_n2e: @ 'cmn': add the inputs, set condition codes, discard the sum
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cmn wrnk,off; bcs near_n2e @ within M2_MAX_OFFSET
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add len,#1 @ too far away, so minimum match length is 3
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ldr tmp,[sp,#sp_DST0]
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sub tmp,off; bhi bad_dst_n2e @ reaching back too far
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cmp tmp,dstlim; bhi bad_dst_n2e @ too much output
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ldrb tmp,[dst] @ force cacheline allocate
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strb tmp,[dst]; add dst,#1
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sub len,#1; bne copy_n2e
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.size ucl_nrv2e_decompress_8, .-ucl_nrv2e_decompress_8
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removed
src/stub/arm_nrv2e_d8.S
