diff options
Diffstat (limited to 'device/lib/pic16/startup/crt0i.c')
| -rw-r--r-- | device/lib/pic16/startup/crt0i.c | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/device/lib/pic16/startup/crt0i.c b/device/lib/pic16/startup/crt0i.c new file mode 100644 index 0000000..d54943a --- /dev/null +++ b/device/lib/pic16/startup/crt0i.c @@ -0,0 +1,247 @@ +/*------------------------------------------------------------------------- + crt0i.c - SDCC pic16 port runtime start code with initialisation + + Copyright (C) 2004, Vangelis Rokas <vrokas at otenet.gr> + Copyright (C) 2012, Molnár Károly <molnarkaroly@users.sf.net> + + 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; +} |