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Diffstat (limited to 'firmware/target/sh/archos/descramble.S')
| -rw-r--r-- | firmware/target/sh/archos/descramble.S | 121 |
1 files changed, 0 insertions, 121 deletions
diff --git a/firmware/target/sh/archos/descramble.S b/firmware/target/sh/archos/descramble.S deleted file mode 100644 index 0ab5e93dce..0000000000 --- a/firmware/target/sh/archos/descramble.S +++ /dev/null @@ -1,121 +0,0 @@ -/*************************************************************************** - * __________ __ ___. - * Open \______ \ ____ ____ | | _\_ |__ _______ ___ - * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / - * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < - * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ - * \/ \/ \/ \/ \/ - * $Id$ - * - * Copyright (C) 2004 by Jens Arnold - * - * This program is free software; you can redistribute it and/or - * modify it 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 software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY - * KIND, either express or implied. - * - ****************************************************************************/ - - .section .icode,"ax",@progbits - - .align 2 /* this aligns to 2^2=4 byte bounday */ - .global _descramble - .type _descramble,@function - -/* Descramble a block of byte data, from source to dest, processing len - * bytes. Size only limited by the len argument. Note that len must - * be an even multiple of 4 (something rolo_load() already assumes. - * (Does the Archos firmware loader also require that?). - * - * Returns the 16-bit "sum" checksum of the descrambled data. - * - * Arguments: - * r4 - source (unsigned char*) - * r5 - dest (unsigned char*) - * r6 - len (unsigned int) - * - * Register usage: - * r0 - data - * r1 - temp - * r2 - checksum - * r3 - current src address - * r4 - source - * r5 - dest - * r6 - len -> source_end - * r7 - dest_end - * r8 - len / 4 - */ - -_descramble: - mov.l r8,@-r15 - mov r6,r8 - shlr2 r8 /* r8 = len / 4 */ - mov r5,r7 - add r6,r7 /* dest_end = dest + len */ - add r4,r6 /* source_end = source + len */ - mov r4,r3 /* addr = source */ - mov #0,r2 /* checksum = 0 */ - -.loop: - mov.b @r3,r0 /* data = *addr */ - add r8,r3 /* addr += len / 4 */ - extu.b r0,r0 /* zero extend data byte */ - swap.b r0,r1 /* byte swap low word to temp */ - or r1,r0 /* r0's two lower bytes now identical */ - shlr r0 /* -> this equals "rotr.b r0" now */ - not r0,r0 /* negate */ - extu.b r0,r0 /* zero extend low byte (only needed for sum) */ - mov.b r0,@r5 /* *dest = data */ - add r0,r2 /* checksum += data */ - add #1,r5 /* dest++ */ - cmp/hi r3,r6 /* addr < source_end ? */ - bt .loop - - add #1,r4 /* source++ */ - mov r4,r3 /* addr = source */ - cmp/hi r5,r7 /* dest < dest_end */ - bt .loop - -/* 15 clock cycles if no reset of source address, 19 if reset, - * avg. 16 cycles per byte. Magnus' Version needed 17-22 cycles per byte - */ - - mov.l @r15+,r8 - rts - extu.w r2,r0 - - -/* Move len bytes from source to dest (which must be suitably aligned for - * long moves) and jump to dest + 0x200. - * - * Arguments: - * r4 - source - * r5 - dest - * r6 - len - */ - - .align 2 - .global _rolo_restart - .type _rolo_restart,@function - -_rolo_restart: - mov r5,r0 - sub r4,r0 /* r0 = dest - source */ - add #-4,r0 /* adjust for early increment */ - add r4,r6 /* r6 = source + len */ - -.copy: /* loop takes 6 cycles per longword */ - mov.l @r4+,r1 - cmp/hi r4,r6 - mov.l r1,@(r0,r4) - bt .copy - - mov.l @r5+,r0 /* start address from image */ - jmp @r0 - mov.l @r5+,r15 /* stack pointer from image */ - -.end: - .size _descramble,.end-_descramble |