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

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
+ */
+