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|
;--------------------------------------------------------------------------
; crt0_rle.s
;
; Copyright (C) 2001, Michael Hope
;
; This library 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, or (at your option) any
; later version.
;
; This library 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 library; see the file COPYING. If not, write to the
; Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
; MA 02110-1301, USA.
;
; As a special exception, if you link this library with other files,
; some of which are compiled with SDCC, to produce an executable,
; this library does not by itself cause the resulting executable to
; be covered by the GNU General Public License. This exception does
; not however invalidate any other reasons why the executable file
; might be covered by the GNU General Public License.
;--------------------------------------------------------------------------
.area _CODE
;; Special RLE decoder used for initing global data
__initrleblock::
;; Pull the destination address out
ld c,l
ld b,h
;; Pop the return address
pop hl
1$:
;; Fetch the run
ld e,(hl)
inc hl
;; Negative means a run
bit 7,e
jp Z,2$
;; Code for expanding a run
ld a,(hl)
inc hl
3$:
ld (bc),a
inc bc
inc e
jp NZ,3$
jp 1$
2$:
;; Zero means end of a block
xor a
or e
jp Z,4$
;; Code for expanding a block
5$:
ld a,(hl)
inc hl
ld (bc),a
inc bc
dec e
jp NZ,5$
jp 1$
4$:
;; Push the return address back onto the stack
push hl
ret
|
