Re: [Amforth-devel] HOW TO - Assembler in anmforth

[pito <pi...@vo...>]

Matthias, Marcin - here is the template for function fuX. Is the
construction ok? It will be assembled by normal asm. Pito.

; amforth 4.1
; ..core\words\fuX.asm
; ( a b c --  m l k ) Function fuX
; R( ? -- ? )
; calculates a special function fuX
; it uses ALL registers except Y
; it calls subroutines placed within the word fuX
; does not use Y - points the data stack
VE_FUX:
.dw $ff03    ;?
.db "fuX",0
.dw VE_HEAD
.set VE_HEAD = VE_FUX
XT_FUX:
.dw PFA_FUX
PFA_FUX:
push R0			; worst case - store everything
push R1
push R2
.....
push R31

ld R10, Y+
ld R11, Y+   ; takes c from stack

ld R12, Y+
ld R13, Y+   ; takes b from stack

ld R14, Y+
ld R15, Y+   ; takes a from stack

do_something

work_with_RAM_indirect_Using_Z

work_with_RAM_indirect_Using_X

call sub3

do_something

jmp label1

do_something

label1:

do_something

jmp label2      ; ijmp rjmp as well

do_something

call sub3

do_something

jmp label3

label2:

do_something

call sub1			; rcall icall as well

call sub2

do_something

label3:

do_something

call sub2

st -Y, R16
st -Y, R17   	; puts m on stack

st -Y, R18
st -Y, R19  	; puts l on stack

st -Y, R20
st -Y, R21   	; puts k on stack


pop R31			; worst case housekeeping
....
pop R2
pop R1
pop R0

jmp label_end   ; jmp to the end of the word "fuX"

sub1: 
do_something

call sub3

ret

sub2: 
do_something

call sub1

ret

sub3: 
do_something

work_with_RAM_indirect_Using_Z

work_with_RAM_indirect_Using_X

ret

label_end:			
jmp_ DO_NEXT		; this is the end of the word "fuX"