/*------------------------------------------------------------------------- crt0i.c - SDCC pic16 port runtime start code with initialisation Copyright (C) 2004, Vangelis Rokas Copyright (C) 2012, Molnár Károly 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. ------------------------------------------------------------------------- $Id: crt0i.c 9317 2015-09-13 08:19:01Z spth $ */ /* * based on Microchip MPLAB-C18 startup files */ extern int stack_end; extern int TBLPTRU; extern int TBLPTRH; extern int TBLPTRL; extern int FSR0L; extern int FSR0H; extern int TABLAT; extern int POSTINC0; #if 1 /* Global variable for forcing gplink to add _cinit section. */ char __uflags = 0; #endif /* External reference to the user's main routine. */ extern void main (void); void _entry (void) __naked __interrupt 0; void _startup (void) __naked; /* Access bank selector. */ #define a 0 /* * Entry function, placed at interrupt vector 0 (RESET). */ void _entry (void) __naked __interrupt 0 { __asm goto __startup __endasm; } /* The cinit table will be filled by the linker. */ extern __code struct { unsigned short num_init; struct { unsigned long from; unsigned long to; unsigned long size; } entries[1]; } cinit; #define TBLRDPOSTINC tblrd*+ #define src_ptr 0x00 /* 0x00 0x01 0x02*/ #define byte_count 0x03 /* 0x03 0x04 */ #define entry_count 0x05 /* 0x05 0x06 */ #define entry_ptr 0x07 /* 0x07 0x08 0x09 */ void _startup (void) __naked { __asm ; Initialize the stack pointer lfsr 1, _stack_end lfsr 2, _stack_end ; 1st silicon does not do this on POR clrf _TBLPTRU, a ; Initialize the flash memory access configuration. ; This is harmless for non-flash devices, so we do it on all parts. bsf 0xa6, 7, a ; EECON1.EEPGD = 1, TBLPTR accesses program memory bcf 0xa6, 6, a ; EECON1.CFGS = 0, TBLPTR accesses program memory /* Initialize global and/or static variables. */ /* * Access registers 0x00 - 0x09 are not saved in this code. */ ; TBLPTR = &cinit movlw low(_cinit) movwf _TBLPTRL, a movlw high(_cinit) movwf _TBLPTRH, a movlw upper(_cinit) movwf _TBLPTRU, a ; entry_count = cinit.num_init TBLRDPOSTINC movff _TABLAT, entry_count TBLRDPOSTINC movff _TABLAT, (entry_count + 1) ; while (entry_count) bra entry_loop_dec entry_loop: ; Count down so we only have to look up the data in _cinit once. ; At this point we know that TBLPTR points to the top of the current ; entry in _cinit, so we can just start reading the from, to, and ; size values. ; Read the source address low. ; src_ptr = entry_ptr->from; TBLRDPOSTINC movff _TABLAT, src_ptr ; source address high TBLRDPOSTINC movff _TABLAT, (src_ptr + 1) ; source address upper TBLRDPOSTINC movff _TABLAT, (src_ptr + 2) ; Skip a byte since it is stored as a 32bit int. TBLRDPOSTINC ; Read the destination address directly into FSR0 ; destination address low. ; FSR0 = (unsigned short)entry_ptr->to; TBLRDPOSTINC movff _TABLAT, _FSR0L ; destination address high TBLRDPOSTINC movff _TABLAT, _FSR0H ; Skip two bytes since it is stored as a 32bit int. TBLRDPOSTINC TBLRDPOSTINC ; Read the size of data to transfer to destination address. ; byte_count = (unsigned short)entry_ptr->size; TBLRDPOSTINC movff _TABLAT, byte_count TBLRDPOSTINC movff _TABLAT, (byte_count + 1) ; Skip two bytes since it is stored as a 32bit int. TBLRDPOSTINC TBLRDPOSTINC ; src_ptr = entry_ptr->from; ; FSR0 = (unsigned short)entry_ptr->to; ; byte_count = (unsigned short)entry_ptr->size; ; The table pointer now points to the next entry. Save it ; off since we will be using the table pointer to do the copying ; for the entry. ; entry_ptr = TBLPTR movff _TBLPTRL, entry_ptr movff _TBLPTRH, (entry_ptr + 1) movff _TBLPTRU, (entry_ptr + 2) ; Now assign the source address to the table pointer. ; TBLPTR = src_ptr movff src_ptr, _TBLPTRL movff (src_ptr + 1), _TBLPTRH movff (src_ptr + 2), _TBLPTRU bra copy_loop_dec copy_loop: TBLRDPOSTINC movff _TABLAT, _POSTINC0 copy_loop_dec: ; while (--byte_count); ; Decrement and test the byte counter. ; The cycle ends when the value of counter reaches the -1. decf byte_count, f, a bc copy_loop decf (byte_count + 1), f, a bc copy_loop ; Restore the table pointer for the next entry. ; TBLPTR = entry_ptr movff entry_ptr, _TBLPTRL movff (entry_ptr + 1), _TBLPTRH movff (entry_ptr + 2), _TBLPTRU entry_loop_dec: ; while (--entry_count); ; Decrement and test the entry counter. ; The cycle ends when the value of counter reaches the -1. decf entry_count, f, a bc entry_loop decf (entry_count + 1), f, a bc entry_loop __endasm; /* Call the main routine. */ main (); __asm lockup: ; Returning from main will lock up. bra lockup __endasm; }