The Microcontroller Idea Book - Jan Axelson's Lakeview Research

Calling Assembly-language Routines
Listing 13-7. (page 2 of 2)
;can add up to 1Fh tokens
;final token must end with 0ffh
org vectortable ;vector table address
dw tggp10 ;label to branch to on
;TGGP10 command
dw setp10 ;label to branch to on
;SETP10 command
dw clrp10 ;label to branch to on
;CLRP10 command
tggp10 org 3000h ;use any available address
cpl p1.0 ;complement Port 1, bit 0
;(pin 1)
ret
;return to BASIC-52
setp10 org 3010h ;use any available address
setb p1.0 ;set Port 1, bit 0 (pin 1)
ret
;return to BASIC-52
clrp10 org 3020h ;use any available address
clr p1.0 ;clear Port 1, bit 0 (pin 1)
ret
;return to BASIC-52
end
The vector table consists of a list of labels corresponding to the beginning of each
assembly-language routine.
In addition to the tables, you must store the assembly-language routines themselves, again
using any free code/data or code memory.
To use Listing 13-7, you must assemble it and upload the resulting Intel Hex file into NV
memory that will be preserved on powering down or rebooting. Reboot, and you can use
the new keywords TGGP10, SETP10, and CLRP10 to control bit 0 of Port 1. (Notice that
the “bit-toggle”keyword is TGGP10, rather than TOGP10, which contains the keyword TO
and so won’t work.)
The Microcontroller Idea Book 235