Page 404 - Programming Microcontrollers in C

Putting It All Together 389

clra ; reset the bss
clrb
ldx #__sbss ; start of bss
bra loop ; start loop
zbcl:
std 2,x+ ; clear word
loop:
cpx #__memory ; up to the end
blo zbcl ; and loop
lds #__stack ; initialize stack pointer
jsr _main ; execute main
_exit:
bra _exit ; stay here
;
end

Listing 7-19: Crts.s C Program Start-Up Function
Any linker for an embedded system requires some type of linker
command file. The command file for this application is as follows.
# link command file for test program
# Copyright (c) 1996 by COSMIC Software
#
+seg .text -b 0x8000 -n .text# program start address
+seg .const -a .text # constants follow program
+seg .data -b 0x800 # data start address
+seg .eeprom -b 0xd00 -m768 #identify EEPROM block
+def __sbss=@.bss # start address of bss
crts.o # startup routine
monitor.o # applications programs
saveit.o
encode.o
decode.o
reset.o
numbdup.o
putbcd.o
priout.o
priafter.o
serial.o