PROGRAM

#include "CPU_65202.CPU"



ROM_START = 0x000000
IO_START = 0x000000
RAM_START = ROM_START + 0x400
DEFAULT_N_PAGE = RAM_START
STACK_START = RAM_START + 0x200

STR_SPACE = RAM_START + 0x300

TERM = IO_START					; Serial Terminal
KEYB = IO_START					; Serial Keyboard
KEYS = IO_START + 1				; Keyboard Status
EXTR = IO_START + 1				; Something else


INT_VAR_0 = DEFAULT_N_PAGE
INT_VAR_1 = DEFAULT_N_PAGE + 2
INT_VAR_2 = DEFAULT_N_PAGE + 4
INT_VAR_3 = DEFAULT_N_PAGE + 6
INT_VAR_4 = DEFAULT_N_PAGE + 8
INT_VAR_5 = DEFAULT_N_PAGE + 10
INT_VAR_6 = DEFAULT_N_PAGE + 12
INT_VAR_7 = DEFAULT_N_PAGE + 14

STR_PNT_0 = DEFAULT_N_PAGE + 0x80
STR_PNT_1 = DEFAULT_N_PAGE + 0x80 + 3
STR_PNT_2 = DEFAULT_N_PAGE + 0x80 + 6
STR_PNT_3 = DEFAULT_N_PAGE + 0x80 + 9





ASCII_ZERO = 0x30
ASCII_LF = 0x0A



INIT:
	DI
	LD A, 0x0000
	LD X, A
	LD Y, A
	LD SN, STACK_START[23:16]
	LD SP, STACK_START[15:0]
	LD N, DEFAULT_N_PAGE[23:8]
	LD ITP, INT_VECTORS
	CLF
	EI
	JMP START

INT_VECTORS:
	#d24 INT_HANDLER[23:0]		; INT Vector
	#d24 NMI_HANDLER[23:0]		; NMI Vector


INT_HANDLER:

RET

NMI_HANDLER:

RET


START:

	LD [STR_PNT_0], STR_SPACE[23:16]
	LD [STR_PNT_0 + 1], STR_SPACE[15:8]
	LD [STR_PNT_0 + 2], STR_SPACE[7:0]

	LD XL, ASCII_LF

	CALL GET_STR

	CALL PRINT_STR


HALT





CNT_MEM_STR:
	;#str "kB of Memory detected\n\0"






CNT_MEM:				; Counts the amount of RAM in the system in kB (banked RAM ignored), starts from RAM_START, uses (INT_VAR_0) and the bottom half of INT_VAR_1

RET


PRINT_STR:				; Prints a String to (TERM) from the address stored at (STR_PNT_0), Strings are Null Terminated
	DXO
	PUSH YL
	LD YL, 0x00
	.LOOP:
		LD AL, ([STR_PNT_0], Y)
		CMP 0x00
		JR Z .EXIT
		OUT (TERM), AL
		INC YL
	JR NO .LOOP
	LD AL, 0xFF
	POP YL
RET
	.EXIT:
	LD AL, 0x00
	POP YL
RET


GET_STR:				; Stores a String from (KEYB) to Memory using the address stored at (STR_PNT_0) until the read byte equals XL, then it replaces that byte with 0x00
	DXO
	PUSH YL
	LD YL, 0x00
	.LOOP:
		.WAIT_DATA:
			IN AL, (KEYS)
			CMP XL
		JR Za .WAIT_DATA
		JR Z .EXIT
		LD ([STR_PNT_0], Y), AL
		INC YL
	JR NO .LOOP
	LD AL, 0xFF
	POP YL
RET
	.EXIT:
	LD AL, 0x00
	LD ([STR_PNT_0], Y), AL
	POP YL
RET


CMP_STR:				; Compares 2 Strings from (STR_PNT_0) and (STR_PNT_1) until both strings end with 0x00 or one with 0x00 and the other with XL

RET


INT8_STR:				; Converts an 8-bit Integer from the bottom half of INT_VAR_0 into a string stored at (STR_PNT_0), string is null-terminated

RET


INT16_STR:				; Converts a 16-bit Integer from INT_VAR_0 into a string stored at (STR_PNT_0), string is null-terminated

RET


IMUL_8:					; Multiplies 2 8-Bit Integers from the bottom half of INT_VAR_0 and INT_VAR_1 and stores the result in AL

RET


IMUL_16:				; Multiplies 2 16-Bit Integers from INT_VAR_0 and INT_VAR_1 and stores the result in A

RET


IDIV_8:					; Divides 2 8-Bit Integers from the bottom half of INT_VAR_0 and INT_VAR_1 (INT_VAR_0 / INT_VAR_1 = AL) and stores the result in AL (remainder in Y)

RET


IDIV_16:				; Divides 2 16-Bit Integers from INT_VAR_0 and INT_VAR_1 (VAR_0 / VAR_1 = A) and stores the result in A (remainder in XY)

RET