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

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

> Please keep in mind that machine stack is not 
> indefinite (64 bytes only). So if your routine
> is pushing something on stack and doing some
> calls it can get tight.
I've changed that to 256:
.set rstackstart = RAMEND      ; start address of return stack,
grows downward
.set stackstart  = RAMEND - 256 ; 80 start address of data stack,
grows downward
> Regarding you other email, regarding "here", "dp"
> etc. DP and HERE are stored in EEPROM (in my case
> EEPROM
So when RAM is needed within fuX word and only there, I have to read
HERE and DP and from that point to allocate RAM fro fuX. When
leaving fuX, I do not need to write the new pointers to EEPROM, I
just leave that as they are (as I do not need RAM anymore..

So the template for fictious word 'fuX' is now (based on my amforth
.lst as the Registers are concerned):

; amforth 4.1
; ..core\words\fuX.asm
; Function fuX( a b c --  m l k ) 
; 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
push R1
; R2 you may use, restore to 0	
; R3 you may use, restore to 0	
push R4
push R5
push R6
push R7
push R8
push R9
push R10
push R11
push R12
push R13
; R14 you may use, no need to push/pop, = temp4
; R15 you may use, no need to push/pop, = temp5
; R16 you may use, no need to push/pop, = temp0
; R17 you may use, no need to push/pop, = temp1
; R18 you may use, no need to push/pop, = temp2
; R19 you may use, no need to push/pop, = temp3
; R20 you may use, no need to push/pop, = temp6
; R21 you may use, no need to push/pop, = temp7
push R22
push R23
; R24 do not push/pop, = tosl
; R25 do not push/pop, = tosh
push R26
push R27
; R28 do not use, = Y
; R29 do not use, = Y
; R30 you may use, no need to push/pop, = Z
; R31 you may use, no need to push/pop, = Z

do_something
ld R24, Y+
ld R25, Y+   ; takes c from stack
do_something
ld R24, Y+
ld R25, Y+   ; takes b from stack
do_something
ld R24, Y+
ld R25, 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
do_something
st -Y, R25
st -Y, R24   	; puts m on stack
do_something
st -Y, R25
st -Y, R24  	; puts l on stack
do_something
st -Y, R24
st -Y, R25   	; puts k on stack

pop R27			; RESTORE REGISTERS IN REVERSE ORDER
....
pop R4
ldi R3, 0
ldi R2, 0
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"