/* lzma_d.S -- ARM decompressor for LZMA

   This file is part of the UPX executable compressor.

   Copyright (C) Markus Franz Xaver Johannes Oberhumer
   Copyright (C) Laszlo Molnar
   Copyright (C) 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>               <ezerotven+github@gmail.com>

   John F. Reiser
   <jreiser@users.sourceforge.net>
*/

#define section .section

  section LZMA_ELF00
//decompress:  // (uchar const *src, size_t lsrc, uchar *dst, u32 &ldst, uint method)
/* Arguments according to calling convention */
src  .req r0
lsrc .req r1
dst  .req r2
ldst .req r3  /* Out: actually a reference: &len_dst */

  // bkpt  // debugging

#if defined(LINUX_ARM_CACHEFLUSH)||defined(DARWIN_ARM_CACHEFLUSH)  /*{*/
        PUSH {dst,ldst, fp,lr}  // dst,ldst for cache flush
#else  /*}{*/
        PUSH {          fp,lr}
#endif  /*}*/

a0 .req r0
#define a1 r1  // bug: a1 .req r1
#define a2 r2  // bug: a2 .req r2
#define a3 r3  // bug: a3 .req r3
#define a4    [sp,#0*4] /* outp */
#define a5    [sp,#1*4] /* outSize */
#define a6    [sp,#2*4] /* &outSizeProcessed */
#define inSzP      3*4  /*   inSizeprocessed */
#define State      4*4  /* CLzmaDecoderState */

//LzmaDecode(  // from lzmaSDK/C/7zip/Compress/LZMA_C/LzmaDecode.h
//      a0= &CLzmaDecoderState,
//      a1= inp,  a2= inSize,  a3= &inSizeProcessed,
//      a4= outp, a5= outSize, a6= &outSizeProcessed
//)
#define LZMA_BASE_SIZE 1846
#define LZMA_LIT_SIZE   768

        ldrb fp,[src,#0]  // first byte, replaces LzmaDecodeProperties()
        mov ip,#2*LZMA_LIT_SIZE
        mov fp,fp,LSR #3  // lit_context_bits + lit_pos_bits
        mov ip,ip,LSL fp  // 2*LZMA_LIT_SIZE << (lit_context_bits + lit_pos_bits)
        mov fp,sp
#define W 4  /* even #bits to round up so that 8 bits span all the 1's */
        add ip,ip,#((~(~0<<W) + State + 2*LZMA_BASE_SIZE)>>W)<<W
        sub sp,sp,ip

        ldr ip,[ldst]
        str ldst,a6  // &outSizeProcessed
        str ip,  a5  // outSize
        str dst, a4   // outp

        add r3,sp,#inSzP
        mov ip,#0
1:  // clear inSizeProcessed and CLzmaDecoderState
        str ip,[r3],#4
        cmp r3,fp
        bne 1b

        add a3,sp,#inSzP // &inSizeProcessed
        sub a2,lsrc,#2  // inSize
        mov a1, src  // inp

        ldrb ip,[a1],#1  // first byte, replaces LzmaDecodeProperties()
        and  ip,ip,#7  // posBits
        strb ip,[sp,#2 + State]
        ldrb ip,[a1],#1  // second byte, replaces LzmaDecodeProperties()
        mov  a0,ip,LSR #4  // lit_pos_bits
        strb a0,[sp,#1 + State]
        and  ip,ip,#0xf  // lib_context_bits
        strb ip,[sp,#0 + State]

        add a0,sp,#State
        bl 1f  // call C-language LzmaDecompress
        mov sp,fp

#if defined(LINUX_ARM_CACHEFLUSH)  /*{*/
        mov r3,r0  // save result value
        POP {r0,r1}  // dst, ldst
        ldr r1,[r1]  // ldst by reference
        add r1,r1,r0  // just beyond what was written
        mov r2,#0
        do_sys2 __ARM_NR_cacheflush  // decompressed region
        mov r0,r3  // result value
#endif  /*}*/
#if defined(DARWIN_ARM_CACHEFLUSH)  /*{*/
        mov r4,r0  // save result value
        POP {r0,r1}  // dst, ldst
        ldr r1,[r1]  // ldst by reference
        PUSH {r0,r1}; do_dcache_flush
        POP  {r0,r1}; do_icache_invalidate
        mov r0,r4  // result value
#endif  /*}*/

        POP {fp,pc}  // RETURN!

1: // either LZMA_DEC10 or LZMA_DEC20 inserted next by buildLinuxLoader

  section LZMA_DEC20
#include "lzma_d_cf.S"

  section LZMA_DEC10
#if 0  /*{*/
#include "lzma_d_cs.S"
#else  /*}{*/
#define PARAMETER_STYLE 3
#include "lzma_d-arm.S"
#endif  /*}*/

  section LZMA_DEC30

// vi:ts=8:et

