Commit af4998387178bf86284d2e0032a7b5ef3d841098 - x6502

Functioning vterm mode. This creates a virtual terminal that the emulated program can get direct character access to. It uses the same dimensions as the C64 terminal (40 rows, 25 cols). The screen of the virtual terminal is mapped to memory addresses $FB00-$FEE7, and is in row-major format. Will Haldean Brown 7 years ago

9 changed file(s) with 84 addition(s) and 34 deletion(s). Raw diff Collapse all Expand all

-0

README less more

54	54	To disable these extensions, compile with
55	55	-DDISABLE_EXTENSIONS (right now, this can be done by
56	56	adding that flag to the Makefile).
	57
	58	This also implements a subset of the 65C02 and 65C816
	59	instruction set, in particular the WAI (0xCB)
	60	instruction. The WAI instruction pauses the emulator
	61	until an I/O interrupt is thrown.
57	62
58	63	I/O memory map:
59	64

-1

emu.c less more

24	24	// branch_offset is an offset that will be added to the program counter
25	25	// after we move to the next instruction
26	26	int8_t branch_offset = 0;
	27
	28	// if set to true, the next instruction will not be executed until an
	29	// interrupt is fired from the IO bus and handled.
	30	uint8_t wait_for_interrupt = 0;
27	31
28	32	init_io();
29	33

55	59	#include "opcode_handlers/compare.h"
56	60	#include "opcode_handlers/flags.h"
57	61	#include "opcode_handlers/incdec.h"
	62	#include "opcode_handlers/interrupts.h"
58	63	#include "opcode_handlers/jump.h"
59	64	#include "opcode_handlers/load.h"
60	65	#include "opcode_handlers/logical.h"

73	78	}
74	79	m->pc += branch_offset;
75	80
76		handle_io(m);
	81	do {
	82	handle_io(m);
	83	} while (wait_for_interrupt && !m->interrupt_waiting);
	84	wait_for_interrupt = 0;
77	85
78	86	if (m->interrupt_waiting && !get_flag(m, FLAG_INTERRUPT)) {
79	87	STACK_PUSH(m) = (m->pc & 0xFF00) >> 8;

+14

-13

io.c less more

6	6
7	7	#include "functions.h"
8	8
9		#define VTERM_ROWS 40
10		#define VTERM_COLS 25
	9	#define VTERM_ROWS 25
	10	#define VTERM_COLS 40
11	11
12	12	uint8_t io_modeflags = 0x00;
	13
	14	WINDOW *window = NULL;
13	15
14	16	void init_vterm();
15	17	void update_vterm(cpu *, uint16_t);

32	34	initscr();
33	35	// reinit IO after initializing the ncurses window
34	36	init_io();
	37
	38	window = newwin(VTERM_ROWS + 2, VTERM_COLS + 2, 0, 0);
	39	box(window, 0, 0);
35	40	}
36	41
37	42	void finish_vterm() {
38		if (io_modeflags & IO_MODEFLAG_WAIT_TERMINATE) {
39		// wait for user to hit enter to quit
40		printw("\nterminated. hit any key to exit.");
41		nodelay(stdscr, FALSE);
42		getch();
43		}
44	43	endwin();
45	44	}
46	45

62	61	// this is in the unused 24 bytes at the end of the page, ignore it
63	62	return;
64	63	}
65		uint8_t r = offset / VTERM_COLS;
66		uint8_t c = offset % VTERM_COLS;
67		mvprintw(r, c, "%c", m->mem[dirty]);
	64	// 1 offsets to avoid overwriting the border
	65	uint8_t r = offset / VTERM_COLS + 1;
	66	uint8_t c = offset % VTERM_COLS + 1;
	67	mvwprintw(window, r, c, "%c", m->mem[dirty]);
	68	wrefresh(window);
68	69	}
69	70
70	71	void handle_io(cpu *m) {

78	79	uint16_t addr = m->dirty_mem_addr;
79	80	if (addr == IO_PUTCHAR) {
80	81	if (io_modeflags & IO_MODEFLAG_VTERM) {
81		addch(m->mem[addr]);
82		refresh();
	82	wprintw(window, "%c", m->mem[addr]);
	83	wrefresh(window);
83	84	} else {
84	85	printf("%c", m->mem[addr]);
85	86	}

-2

io.h less more

8	8	#define IO_VTERM_START 0xFB00
9	9	#define IO_VTERM_END 0xFF00
10	10
11		#define IO_MODEFLAG_WAIT_TERMINATE 0x01
12		#define IO_MODEFLAG_VTERM 0x02
	11	#define IO_MODEFLAG_VTERM 0x01
13	12
14	13	void init_io();
15	14	void finish_io();

+14

-0

opcode_handlers/interrupts.h less more

	0	case BRK:
	1	set_flag(m, FLAG_BREAK, 1);
	2	m->interrupt_waiting = 1;
	3	break;
	4
	5	case RTI:
	6	m->sr = STACK_POP(m);
	7	arg1 = STACK_POP(m);
	8	m->pc = mem_abs(arg1, STACK_POP(m), 0);
	9	break;
	10
	11	case WAI:
	12	wait_for_interrupt = 1;
	13	break;

-11

opcode_handlers/jump.h less more

23	23	arg1 = STACK_POP(m);
24	24	m->pc = mem_abs(arg1, STACK_POP(m), 0) + 1;
25	25	break;
26
27		case BRK:
28		set_flag(m, FLAG_BREAK, 1);
29		m->interrupt_waiting = 1;
30		break;
31
32		case RTI:
33		m->sr = STACK_POP(m);
34		arg1 = STACK_POP(m);
35		m->pc = mem_abs(arg1, STACK_POP(m), 0);
36		break;

-0

opcodes.h less more

217	217	#define TXS 0x9A
218	218	#define TYA 0x98
219	219
	220	#define WAI 0xCB
	221
220	222	#endif

-1

sample_programs/README less more

0	0	Test 6502 assembler programs. Generate binaries with:
1	1
2		xa -bt0 -Istdlib/ sample_programs/test.s
	2	xa -w -bt0 -Istdlib/ sample_programs/test.s
3	3
4	4	xa is a cross-assembler and utility suite for 65xx series processors. It's
5	5	included in many package repositories as `xa65', including Homebrew on OSX in

+38

-6

sample_programs/spam.s less more

0	0	counter = $0100
	1	supercounter = $0101
	2	page = $FF
	3	char = $FD
1	4
2		lda #$03 ; set WAIT_TERMINATE flag
	5	lda #$01 ; go into vterm mode
3	6	sta $FF02
4	7
5	8	lda #$FF
6	9	sta counter ; init counter
7	10
8		ldx #$0
	11	lda #$FB
	12	sta page
	13	lda #$00
	14	sta page-1
9	15
10		loop lda #$41 ; 41 == 'A'
11		sta $FF00,X
12		inx
13		cpx counter
	16	lda #$41 ; 41 == 'A'
	17	sta char
	18
	19	ldy #$00
	20
	21	loop:
	22	lda char
	23	sta (page-1),Y
	24	jsr incchar
	25
	26	iny
	27	cpy #$00
14	28	bne loop
	29
	30	inc page
	31	lda page
	32	cmp #$FF
	33	bne loop
	34
	35	wai
	36	.byt $FF
	37
	38	incchar:
	39	inc char
	40	lda char
	41	cmp #$5B
	42	bne chardone
	43	lda #$41
	44	chardone:
	45	sta char
	46	rts