| 1 | ;;; -*- asm -*-
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| 2 | ;;;
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| 3 | ;;;-----------------------------------------------------------------------------
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| 4 | ;;; Startup code
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| 5 | ;;;-----------------------------------------------------------------------------
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| 6 | ;;; Code taken from USRP2 firmware (GNU Radio Project), version 3.0.2,
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| 7 | ;;; Copyright 2003 Free Software Foundation, Inc.
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| 8 | ;;;-----------------------------------------------------------------------------
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| 9 | ;;; This code is part of usbjtag. usbjtag is free software; you can redistribute
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| 10 | ;;; it and/or modify it under the terms of the GNU General Public License as
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| 11 | ;;; published by the Free Software Foundation; either version 2 of the License,
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| 12 | ;;; or (at your option) any later version. usbjtag is distributed in the hope
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| 13 | ;;; that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
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| 14 | ;;; warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 15 | ;;; GNU General Public License for more details. You should have received a
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| 16 | ;;; copy of the GNU General Public License along with this program in the file
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| 17 | ;;; COPYING; if not, write to the Free Software Foundation, Inc., 51 Franklin
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| 18 | ;;; St, Fifth Floor, Boston, MA 02110-1301 USA
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| 19 | ;;;-----------------------------------------------------------------------------
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| 20 |
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| 21 | ;;; The default external memory initialization provided by sdcc is not
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| 22 | ;;; appropriate to the FX2. This is derived from the sdcc code, but uses
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| 23 | ;;; the FX2 specific _MPAGE sfr.
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| 24 |
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| 25 |
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| 26 | ;; .area XISEG (XDATA) ; the initialized external data area
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| 27 | ;; .area XINIT (CODE) ; the code space consts to init XISEG
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| 28 | .area XSEG (XDATA) ; zero initialized xdata
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| 29 | .area USBDESCSEG (XDATA) ; usb descriptors
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| 30 |
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| 31 |
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| 32 | .area CSEG (CODE)
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| 33 |
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| 34 | ;; sfr that sets upper address byte of MOVX using @r0 or @r1
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| 35 | _MPAGE = 0x0092
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| 36 |
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| 37 | __sdcc_external_startup::
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| 38 | ;; This system is now compiled with the --no-xinit-opt
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| 39 | ;; which means that any initialized XDATA is handled
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| 40 | ;; inline by code in the GSINIT segs emitted for each file.
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| 41 | ;;
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| 42 | ;; We zero XSEG and all of the internal ram to ensure
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| 43 | ;; a known good state for uninitialized variables.
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| 44 |
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| 45 | ; _mcs51_genRAMCLEAR() start
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| 46 | mov r0,#l_XSEG
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| 47 | mov a,r0
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| 48 | orl a,#(l_XSEG >> 8)
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| 49 | jz 00002$
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| 50 | mov r1,#((l_XSEG + 255) >> 8)
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| 51 | mov dptr,#s_XSEG
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| 52 | clr a
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| 53 |
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| 54 | 00001$: movx @dptr,a
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| 55 | inc dptr
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| 56 | djnz r0,00001$
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| 57 | djnz r1,00001$
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| 58 |
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| 59 | ;; We're about to clear internal memory. This will overwrite
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| 60 | ;; the stack which contains our return address.
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| 61 | ;; Pop our return address into DPH, DPL
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| 62 | 00002$: pop dph
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| 63 | pop dpl
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| 64 |
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| 65 | ;; R0 and A contain 0. This loop will execute 256 times.
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| 66 | ;;
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| 67 | ;; FWIW the first iteration writes direct address 0x00,
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| 68 | ;; which is the location of r0. We get lucky, we're
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| 69 | ;; writing the correct value (0)
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| 70 |
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| 71 | 00003$: mov @r0,a
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| 72 | djnz r0,00003$
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| 73 |
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| 74 | push dpl ; restore our return address
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| 75 | push dph
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| 76 |
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| 77 | mov dpl,#0 ; indicate that data init is still required
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| 78 | ret
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