/*
 * Keyboard buffer stuffer
 *
 * This program copies characters from the command line into the PC
 * keyboard buffer, adding correct "scan code" extensions as it does so.
 * Numerous "escape sequences" are recognized to provide for stuffing
 * non-ASCII characters produced by the various non-alphanumeric keys on
 * the PC keyboard.
 *
 * The default BIOS keyboard buffer holds only 15 entries, however this
 * program uses the START/END pointers from BIOS, so it should work
 * correctly with the various utilities that enlarge the buffer.
 *
 * Copyright 1994-1995 Dave Dunfield
 * All rights reserved.
 *
 * Permission granted for personal (non-commerical) use only.
 *
 * Compile command: CC stuff -fop
 */
#include <stdio.h>

#define	BIOS_SEG		0x40	/* BIOS data segment */
#define	BUFFER_START	0x80	/* Pointer to start of keyboard buffer */
#define	BUFFER_END		0x82	/* Pointer to end of keyboard buffer */
#define	BUFFER_TAIL		0x1A	/* Pointer to next character to receive */
#define	BUFFER_HEAD		0x1C	/* Pointer to first available spot */

/* Prefix codes for "ALPHA" keys */
char alpha_prefix[] = {
	0x1E, 0x30, 0x2E, 0x20, 0x12, 0x21, 0x22, 0x23, 0x17, 0x24,
	0x25, 0x26, 0x32, 0x31, 0x18, 0x19, 0x10, 0x13, 0x1F, 0x14,
	0x16, 0x2F, 0x11, 0x2D, 0x15, 0x2C };

/* Codes for misc. ASCII keys */ 
unsigned ascii_prefix[] = {
	0x3920, 0x0231, 0x0332, 0x0433, 0x0534, 0x0635, 0x0736, 0x0837, 
	0x0938, 0x0A39, 0x0B30, 0x0C2D, 0x0D3D, 0x2B5C, 0x297E, 0x0221, 
	0x0340, 0x0423, 0x0524, 0x0625, 0x0826, 0x092A, 0x0A28, 0x0B29,
	0x0C5F, 0x0D2B, 0x2B7C, 0x1A5B, 0x1B5D, 0x273B, 0x2827, 0x332C,
	0x342E, 0x352F, 0x1A7B, 0x1B7D, 0x273A, 0x2822, 0x333C, 0x343E,
	0x353F, 0x2960, 0 };

/* Table of special keys & codes */
char misc_key[] = {
	'=', '!', '/', '\\',			/* Enter, Backspace, Tab, Backtab */
	'@','0','.', '+', '-',			/* Escape, Ins, Del, keypad+, keypad- */
	'4', '6', '8', '2',				/* Right, Left, Up, Down */
	'7', '1', '9', '3',				/* Home, End, PgUp, PgDn */
	'^' };							/* Single '^' */
unsigned misc_code[] = {
	0x1C0D, 0x0E08, 0x0F09, 0x0F00,
	0x011B, 0x5200, 0x5300, 0x4E2b, 0x4A2D,
	0x4B00, 0x4D00, 0x4800, 0x5000,
	0x4700, 0x4F00, 0x4900, 0x5100,
	0x075E };

/* Help text */
char *help[] = {
	"\nKeyboard buffer stuffer - by Dave Dunfield\n",
	"\nUse: stuff <characters>\n\n",
	"^ = special character:\n\n",
	" ^A-Z Ctrl  ^*A-Z Alt  ^#0-9 Fn  ^$0-9 SFn  ^%0-9 CFn  ^&0-9 AFn\n\n",
    " ^. Del     ^0 Ins     ^1 End    ^2 Down    ^3 PgDn    ^4 Left\n",
	" ^6 Right   ^7 Home    ^8 Up     ^9 PgUp    ^+ Kpad+   ^- Kpad-\n\n",
	" ^^ (^)     ^= Enter   ^@ Esc    ^! Backsp  ^/ Tab     ^\\ Backtab\n\n",
	" ^? Clear keyboard buffer\n",
	0 };

/* 
 * Main program - Stuff arguments into the keyboard buffer
 */
main(int argc, char *argv[])
{
	int i;

	if(argc < 2) {		/* No data to stuff, display help */
		for(i=0; help[i]; ++i)
			fputs(help[i], stdout);
		return; }

	i = 1;
	while(i < argc) {	/* Stuff all arguments */
		stuff_string(argv[i]);
		if(++i < argc)
			stuff_string(" "); }
}

/*
 * Stuff a string into the keyboard buffer
 */
stuff_string(char *ptr)
{
	int i, j;
	char c, prefix;

	while(c = *ptr++) {
		if(isalpha(c))					/* Normal "ALPHA" character */
			prefix = alpha_prefix[(c & 0x1F) - 1];
		else if(c == '^') {
			if(isalpha(c = *ptr++))		/* ALPHA control code */
				prefix = alpha_prefix[(c &= 0x1F) - 1];
			else switch(c) {
				default:
					for(i=0; i < sizeof(misc_key); ++i)
						if(c == misc_key[i]) {
							stuff_key(misc_code[i]);
							goto done; }
					clear_buffer();
					abort("Unknown ^!\n");
				case '#' :				/* Normal function key */
					prefix = 0x3B;
					goto dofunc;
				case '$' :				/* Shift function key */
					prefix = 0x54;
					goto dofunc;
				case '%' :				/* CTRL function key */
					prefix = 0x5E;
					goto dofunc;
				case '&' :				/* ALT function key */
					prefix = 0x68;
				dofunc:
					if(isdigit(c = *ptr++)) {
						prefix += (c == '0') ? 9 : (c - '1');
						c = 0;
						break; }
					clear_buffer();
					abort("Fkey must be 0-9\n");
				case '?' :				/* Clear buffer */
					clear_buffer();
					continue;
				case '*' :				/* ALT-ALPHA character */
					prefix = alpha_prefix[(*ptr++ & 0x1F) - 1];
					c = 0; } }
		else {
			for(i=0; j = ascii_prefix[i]; ++i)
				if((j & 255) == c) {
					stuff_key(j);
					goto done; }
			clear_buffer();
			abort("Unknown character\n"); }
		stuff_key((prefix << 8) | c);
	done: }
}

/*
 * Stuff a single keystroke into the keyboard buffer
 */
stuff_key(unsigned key)
{
	unsigned head;

	disable();
	pokew(BIOS_SEG, head = peekw(BIOS_SEG, BUFFER_HEAD), key);

	if((head += 2) >= peekw(BIOS_SEG, BUFFER_END))
		head = peekw(BIOS_SEG, BUFFER_START);

	if(head == peekw(BIOS_SEG, BUFFER_TAIL)) {
		clear_buffer();
		abort("Key buffer FULL!\n"); }

	if(head != peekw(BIOS_SEG, BUFFER_TAIL))
	pokew(BIOS_SEG, BUFFER_HEAD, head);
	enable();
}

/*
 * Clear the keyboard buffer
 */
clear_buffer()
{
	disable();
	pokew(BIOS_SEG, BUFFER_HEAD, peekw(BIOS_SEG, BUFFER_TAIL));
	enable();
}