programs/sub-suite/subasm.s


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; SuBAsm
; The Sux Bootstrapped Assembler.
;
; by mr b0nk 500 <b0nk@b0nk.xyz>

subasm:
	ldb #0		; Set the first pointer
	lda.d #cmd_buf	; to the command buffer.
	jsr set_ptr	;
	tba		; Reset A.
	tax		; Reset X.
	jsr chk_shcmd	; Did we get a shortend command?
	bne @cmd	; Yes, so skip everything else.
	jsr chk_cmd	; No, but did we get a full command?
	bne @cmd	; Yes, so skip everything else.
	jsr lex		; No, so start lexing this line.
	bra @end	; We are done.
@cmd:
	ldb #1		; Set the second pointer
	lda.d #cmd_srt	; to the command subroutine table.
	jsr set_ptr	;
	deb		; Reset B.
	tba		; Reset A.
	lda regf	; Get the command ID.
	cmp #8		; Is the command ID greater than the command count?
	bcs @end	; Yes, so we're done.
	lsl #1		; No, so multiply the command ID by two.
	tay		; Set the index to the offset that we just calculated.
	lda.w (ptr2), y	; Get the command subroutine, from the command subroutine table.
	ldb #2		; Save it in the third pointer.
	jsr set_ptr	;
	ldb #0		; Reset B.
	jsr (ptr3)	; Run the command's subroutine.
@end:
	and #0		; Reset A.
	jsr update_ptr	; Get the screen buffer index.
	tay		; Save it in Y.
	and #0		; Reset A.
	rts		; End of subasm.

chk_shcmd:
	tba		; Reset A.
	inb		; Set the second pointer
	lda.w #sh_cmds	; to the shortend command table.
	jsr set_ptr	;
	deb		; Reset B.
	tba		; Reset A.
	phy.w		; Preserve the screen buffer position.
	txy		; Set our index to zero.
	lda (ptr), y	; Is there nothing in the command buffer?
	beq @false	; Yes, so return that we failed.
	cmp #' '	; No, but is this character, a space?
	beq @false	; Yes, so return that we failed.
	jsr tolower	; No, so convert it to lowercase.
@loop:
	ldb (ptr2), y	; Are we at the end of the table?
	beq @false	; Yes, so return that we failed.
	cmp b		; No, so did the character match?
	beq @found	; Yes, so check if there are any arguments.
	iny		; No, so check the next command.
	bra @loop	; Keep looping.
@found:
	sty regf	; Save the command ID.
	ldy #1		; Check the next character in the command buffer.
	lda (ptr), y	; Is this the end of the buffer?
	beq @true	; Yes, so return that we succeded.
	cmp #' '	; No, but is this a space?
	beq @true	; Yes, so return that we succeded.
	bra @false	; No, so return that we failed.
@true:
	lda #1		; Return true.
	bra @end	; We are done.
@false:
	ldb #0		; Reset B.
	tba		; Return false.
	tax		; Reset X.
@end:
	ply.w		; Get back the screen buffer position.
	rts		; End of chk_shcmd.


chk_cmd:
	tba		; Reset A.
	tax		; Reset X.
	sta.q idx0	; Reset the first index.
	sta.q idx1	; Reset the second index.
@loop:
	lda.w #cmds	; Get pointer to the start of the command table.
	clc		; Prepare for a non carrying add.
	adc.w idx0	; Offset the pointer, by the length of the previous string.
	pha.q		; Preserve the command string pointer.
	jsr strcaseg	; Is the command buffer, the same as the command string?
	pla.q		; Get the command string pointer back.
	beq @true	; Yes, so return true.
	ldb idx1	; No, so Get the command ID.
	cpb #7		; Have we reached the end of the command table?
	beq @false	; Yes, so return false.
	inc idx1	; No, so increment the command ID.
@getlen:
	jsr strlen	; Get the string's length.
	inc		; Add one to the length.
	clc		; Prepare for a non carrying add.
	adc.w idx0	; Add the string offset to the current length
	sta.w idx0	; Save the offset in the first index.
	bra @loop	; Keep looping.
@true:
	ldb idx1	; Get the command ID.
	stb regf	; Return the command ID.
	ldb #1		; Return true.
	bra @end	; We are done.
@false:
	ldb #0		; Return false.
@end:
	rts		; End of chk_cmd.

viewmem:
	lda.q prg_cnt	; Get the program counter.
	sta.q idx0	; Save the address in the first index.
	and #$F0	; Clear the first four bits of the address.
	sta idx0	; Overwrite the first byte, with the masked byte.
	lda #19		; Move the cursor to the right, by 19 columns.
	sta scr_col	;
	jsr update_pos	;
	jsr print_lo	; Print the low nibble offsets.
	ldx #0		; Reset X.
	ldb #0		; Reset B.
	stb idx1	; Reset the byte count.
@loop:
	lda #'\n'	; Print a newline.
	jsr print_char	;
	jsr print_hi	; Place the address in the string buffer.
	jsr print_chunk	; Place the next 16 bytes in the string buffer.
	lda.d #strbuf	; Print the string buffer.
	jsr print_str	;
	inc idx1	; Increment the chunk count.
	ldb idx1	; Get the chunk count.
	cpb #$10	; Did we print 16 chunks?
	beq @end	; Yes, so we're done.
	lda.q idx0	; No, so get the address index.
	clc		; Prepare for a non carrying add.
	adc #$10	; Add 16 to the address.
	sta.q idx0	; Put it back into the address.
	and #0		; Reset A.
	bra @loop	; Keep looping.
@end:
	lda #'\n'	; Print a newline.
	jsr print_char	;
	and #0		; Reset A.
	rts		; End of viewmem.


list:
	nop		;
@end:
	rts		; End of list.
asm:
	nop		;
@end:
	rts		; End of asm.
help:
	nop		;
@end:
	rts		; End of help.
inst:
	nop		;
@end:
	rts		; End of inst.
run:
	nop		;
@end:
	rts		; End of run.
set:
	nop		;
@end:
	rts		; End of set.