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;;; -*- asm -*-
;;;
;;; Copyright 2003,2004 Free Software Foundation, Inc.
;;;
;;; This file is part of GNU Radio
;;;
;;; GNU Radio 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.
;;;
;;; GNU Radio 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 GNU Radio; see the file COPYING. If not, write to
;;; the Free Software Foundation, Inc., 51 Franklin Street,
;;; Boston, MA 02110-1301, USA.
;;; The default external memory initialization provided by sdcc is not
;;; appropriate to the FX2. This is derived from the sdcc code, but uses
;;; the FX2 specific _MPAGE sfr.
;; .area XISEG (XDATA) ; the initialized external data area
;; .area XINIT (CODE) ; the code space consts to init XISEG
.area XSEG (XDATA) ; zero initialized xdata
.area USBDESCSEG (XDATA) ; usb descriptors
.area CSEG (CODE)
;; sfr that sets upper address byte of MOVX using @r0 or @r1
_MPAGE = 0x0092
__sdcc_external_startup::
;; This system is now compiled with the --no-xinit-opt
;; which means that any initialized XDATA is handled
;; inline by code in the GSINIT segs emitted for each file.
;;
;; We zero XSEG and all of the internal ram to ensure
;; a known good state for uninitialized variables.
; _mcs51_genRAMCLEAR() start
mov r0,#l_XSEG
mov a,r0
orl a,#(l_XSEG >> 8)
jz 00002$
mov r1,#((l_XSEG + 255) >> 8)
mov dptr,#s_XSEG
clr a
00001$: movx @dptr,a
inc dptr
djnz r0,00001$
djnz r1,00001$
;; We're about to clear internal memory. This will overwrite
;; the stack which contains our return address.
;; Pop our return address into DPH, DPL
00002$: pop dph
pop dpl
;; R0 and A contain 0. This loop will execute 256 times.
;;
;; FWIW the first iteration writes direct address 0x00,
;; which is the location of r0. We get lucky, we're
;; writing the correct value (0)
00003$: mov @r0,a
djnz r0,00003$
push dpl ; restore our return address
push dph
mov dpl,#0 ; indicate that data init is still required
ret
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