ST ST7 - Page 218

218/317
7 - Debugger and PROM Programmer Tutorial for ST72251
ld X, {AddrTasks+4} ; MSB address Task
push X ; Written at top of stack
ld A, S
ld ImStack3, A ; Remember position of stack pointer
ld A, #org2 ; Top of stack for task 2
ld S, A
ld X, {AddrTasks+3} ; LSB address Task
push X
ld X, {AddrTasks+2} ; MSB address Task
push X ; Written at top of stack
ld A, S
ld ImStack2, A ; Remember position of stack pointer
ld A, #org1 ; Top of stack for task 1
ld S, A
ld X, {AddrTasks+1} ; LSB address Task
push X
ld X, AddrTasks ; MSB address Task
push X ; Written at top of stack
ld A, S
ld ImStack1, A ; Remember position of stack pointer
clr Permut ; Set task counter to first
ret ; Jump to first task
; Yield
; =====
Yield:
ld A, #watch ; Loading the watchdog
ld wdgr, A
ld X, Permut ; To select the element where to save
ld A, S ; The stack pointer of the current task
ld (ImStack1,X), A
ld A, X
inc A ; Increment number of task
and A, #3 ; If last, go to first
ld Permut, A
ld X, A
ld A, (ImStack1,X) ; Get next stack pointer
ld S, A
ret
END