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authorDave Chapman <dave@dchapman.com>2008-10-01 08:13:10 +0000
committerDave Chapman <dave@dchapman.com>2008-10-01 08:13:10 +0000
commitfe72d579969b9b5365fb5f430cd8eb265d2f4d44 (patch)
tree78ac0402f70f103951ba43c1881c3ebf5fb01aa7 /utils/AMS/hacking
parent66f5eec8f0e0f533c9ab1798356a656035aa423f (diff)
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Original, unmodified version of the ARM thumb implementation of the UCL ucl_nrv2e_decompress_8 function from upx-3.03 - licensed under the GPL (v2 or later). This will be used to decompress the original firmware image in the next version of mkamsboot.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@18674 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'utils/AMS/hacking')
-rw-r--r--utils/AMS/hacking/nrv2e_d8.S187
1 files changed, 187 insertions, 0 deletions
diff --git a/utils/AMS/hacking/nrv2e_d8.S b/utils/AMS/hacking/nrv2e_d8.S
new file mode 100644
index 0000000000..88df64a58f
--- /dev/null
+++ b/utils/AMS/hacking/nrv2e_d8.S
@@ -0,0 +1,187 @@
+/* arm_nrv2e_d8.S -- ARM decompressor for NRV2E
+
+ This file is part of the UPX executable compressor.
+
+ Copyright (C) 1996-2008 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 1996-2008 Laszlo Molnar
+ Copyright (C) 2000-2008 John F. Reiser
+ All Rights Reserved.
+
+ UPX and the UCL library are free software; you can redistribute them
+ and/or modify them under the terms of the GNU General Public License as
+ published by the Free Software Foundation; either version 2 of
+ the License, or (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; see the file COPYING.
+ If not, write to the Free Software Foundation, Inc.,
+ 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+ Markus F.X.J. Oberhumer Laszlo Molnar
+ <markus@oberhumer.com> <ml1050@users.sourceforge.net>
+
+ John F. Reiser
+ <jreiser@users.sourceforge.net>
+*/
+#define SAFE 0 /* 1 for src+dst bounds checking: cost 40 bytes */
+
+#define src r0
+#define len r1 /* overlaps 'cnt' */
+#define dst r2
+#define tmp r3
+#define bits r4
+#define off r5
+#define wrnk r6 /* 0x500 M2_MAX_OFFSET before "wrinkle" */
+#define srclim r7
+#if 1==SAFE /*{*/
+#define dstlim r12
+#endif /*}*/
+
+#define cnt r1 /* overlaps 'len' while reading an offset */
+
+#if 1==SAFE /*{*/
+#define CHECK_SRC cmp src,srclim; bhs bad_src_n2e
+#define CHECK_DST cmp dst,dstlim; bhs bad_dst_n2e
+#else /*}{*/
+#define CHECK_SRC /*empty*/
+#define CHECK_DST /*empty*/
+#endif /*}*/
+
+#if 0 /*{ DEBUG only: check newly-decompressed against original dst */
+#define CHECK_BYTE \
+ push {wrnk}; \
+ ldrb wrnk,[dst]; \
+ cmp wrnk,tmp; beq 0f; bkpt; \
+0: pop {wrnk}
+#else /*}{*/
+#define CHECK_BYTE /*empty*/
+#endif /*}*/
+
+/* "mov lr,pc; bxx ..." implements conditional subroutine call */
+#define GETBIT add bits,bits; mov lr,pc; beq get1_n2e
+
+#define getnextb(reg) GETBIT; adc reg,reg
+#define jnextb0 GETBIT; bcc
+#define jnextb1 GETBIT; bcs
+
+#ifndef PURE_THUMB
+ucl_nrv2e_decompress_8: .globl ucl_nrv2e_decompress_8 @ ARM mode
+ .type ucl_nrv2e_decompress_8, %function
+/* error = (*)(char const *src, int len_src, char *dst, int *plen_dst)
+ Actual decompressed length is stored through plen_dst.
+ For SAFE mode: at call, *plen_dst must be allowed length of output buffer.
+*/
+ adr r12,1+.thumb_nrv2e_d8; bx r12 @ enter THUMB mode
+ .code 16 @ THUMB mode
+ .thumb_func
+#endif
+
+.thumb_nrv2e_d8:
+ push {r2,r3, r4,r5,r6,r7, lr}
+#define sp_DST0 0 /* stack offset of original dst */
+ add srclim,len,src @ srclim= eof_src;
+#if 1==SAFE /*{*/
+ ldr tmp,[r3] @ len_dst
+ add tmp,dst
+ mov dstlim,tmp
+#endif /*}*/
+ mov bits,#1; neg off,bits @ off= -1 initial condition
+ lsl bits,#31 @ 1<<31: refill next time
+ mov wrnk,#5
+ lsl wrnk,#8 @ 0x500 @ nrv2e M2_MAX_OFFSET
+ b top_n2e
+
+#if 1==SAFE /*{*/
+bad_dst_n2e: # return value will be 2
+ add src,srclim,#1
+bad_src_n2e: # return value will be 1
+ add src,#1
+#endif /*}*/
+eof_n2e:
+ pop {r3,r4} @ r3= orig_dst; r4= plen_dst
+ sub src,srclim @ 0 if actual src length equals expected length
+ sub dst,r3 @ actual dst length
+ str dst,[r4]
+ pop {r4,r5,r6,r7 /*,pc*/}
+ pop {r1}; bx r1 @ "pop {,pc}" fails return to ARM mode on ARMv4T
+
+get1_n2e: @ In: Carry set [from adding 0x80000000 (1<<31) to itself]
+ ldrb bits,[src] @ zero-extend next byte
+ adc bits,bits @ double and insert CarryIn as low bit
+ CHECK_SRC
+ add src,#1
+ lsl bits,#24 @ move to top byte, and set CarryOut from old bit 8
+ mov pc,lr @ return, stay in current (THUMB) mode
+
+lit_n2e:
+ CHECK_SRC; ldrb tmp,[src]; add src,#1
+ CHECK_BYTE
+ CHECK_DST; strb tmp,[dst]; add dst,#1
+top_n2e:
+ jnextb1 lit_n2e
+ mov cnt,#1; b getoff_n2e
+
+off_n2e:
+ sub cnt,#1
+ getnextb(cnt)
+getoff_n2e:
+ getnextb(cnt)
+ jnextb0 off_n2e
+
+ sub tmp,cnt,#3 @ set Carry
+ mov len,#0 @ Carry unaffected
+ blo offprev_n2e @ cnt was 2; tests Carry only
+ lsl tmp,#8
+ CHECK_SRC; ldrb off,[src]; add src,#1 @ low 7+1 bits
+ orr off,tmp
+ mvn off,off; beq eof_n2e @ off= ~off
+ asr off,#1; bcs lenlast_n2e
+ b lenmore_n2e
+
+offprev_n2e:
+ jnextb1 lenlast_n2e
+lenmore_n2e:
+ mov len,#1
+ jnextb1 lenlast_n2e
+len_n2e:
+ getnextb(len)
+ jnextb0 len_n2e
+ add len,#6-2
+ b gotlen_n2e
+
+lenlast_n2e:
+ getnextb(len) @ 0,1,2,3
+ add len,#2
+gotlen_n2e: @ 'cmn': add the inputs, set condition codes, discard the sum
+ cmn wrnk,off; bcs near_n2e @ within M2_MAX_OFFSET
+ add len,#1 @ too far away, so minimum match length is 3
+near_n2e:
+#if 1==SAFE /*{*/
+ ldr tmp,[sp,#sp_DST0]
+ sub tmp,dst
+ sub tmp,off; bhi bad_dst_n2e @ reaching back too far
+
+ add tmp,dst,cnt
+ cmp tmp,dstlim; bhi bad_dst_n2e @ too much output
+#endif /*}*/
+ ldrb tmp,[dst] @ force cacheline allocate
+copy_n2e:
+ ldrb tmp,[dst,off]
+ CHECK_BYTE
+ strb tmp,[dst]; add dst,#1
+ sub len,#1; bne copy_n2e
+ b top_n2e
+
+#ifndef PURE_THUMB
+ .size ucl_nrv2e_decompress_8, .-ucl_nrv2e_decompress_8
+#endif
+
+/*
+vi:ts=8:et:nowrap
+ */
+