/*
 * --- public domain, no warranty.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

/* FONTX2 header */
#define CODETYPE_ASCII	0
#define	CODETYPE_KANJI	1

/* common */
typedef struct {
	uint8_t	identifier[6];
	uint8_t	fontname[8];
	uint8_t	xsize;
	uint8_t	ysize;
	uint8_t	codetype;
} __attribute__((packed)) FONTX2_HEADER;

/* sjis */
typedef	struct {
	uint16_t	start;
	uint16_t	end;
} __attribute__((packed)) FONTX2_CODETABLE;

static	FONTX2_CODETABLE	CodeTable_SJIS1[] = {
	{0x8140, 0x817e}, {0x8180, 0x81ac},	/* symbol */
	{0x824f, 0x8258},			/* number */
	{0x8260, 0x8279},			/* alphabet (large) */
			  {0x8281, 0x829a},	/* alphabet (small) */
			  {0x829f, 0x82f1},	/* hiragana */
	{0x8340, 0x837e}, {0x8380, 0x8396},	/* katakana */
			  {0x839f, 0x83b6},	/* greek (large) */
			  {0x83bf, 0x83d6},	/* greek (small) */
	{0x8440, 0x8460},			/* russian (large) */
	{0x8470, 0x847e}, {0x8480, 0x8491},	/* russian (small) */
			  {0x889f, 0x88fc},	/* kanji (JIS1) */
	{0x8940, 0x897e}, {0x8980, 0x89fc},
	{0x8a40, 0x8a7e}, {0x8a80, 0x8afc},
	{0x8b40, 0x8b7e}, {0x8b80, 0x8bfc},
	{0x8c40, 0x8c7e}, {0x8c80, 0x8cfc},
	{0x8d40, 0x8d7e}, {0x8d80, 0x8dfc},
	{0x8e40, 0x8e7e}, {0x8e80, 0x8efc},
	{0x8f40, 0x8f7e}, {0x8f80, 0x8ffc},
	{0x9040, 0x907e}, {0x9080, 0x90fc},
	{0x9140, 0x917e}, {0x9180, 0x91fc},
	{0x9240, 0x927e}, {0x9280, 0x92fc},
	{0x9340, 0x937e}, {0x9380, 0x93fc},
	{0x9440, 0x947e}, {0x9480, 0x94fc},
	{0x9540, 0x957e}, {0x9580, 0x95fc},
	{0x9640, 0x967e}, {0x9680, 0x96fc},
	{0x9740, 0x977e}, {0x9780, 0x97fc},
	{0x9840, 0x9872},
};

/* font data buffer */
#define	BUFFERSIZE	(65536*4)
static	uint8_t	Buf[BUFFERSIZE];

/* SJIS -> JIS */
static	int	_mbcjmstojis(int jms)
{
	int	low, high;

	high = (jms >> 8) & 0xff;
	low  =  jms       & 0xff;

	if (low < 0x9f) {
		if (high < 0xa0) {
			high -= 0x81;
			high *= 2;
			high += 0x21;
		} else {
			high -= 0xe0;
			high *= 2;
			high += 0x5f;
		}
			
		if (low > 0x7f) low--;
		low -= 0x1f;
	} else {
		if (high < 0xa0) {
			high -= 0x81;
			high *= 2;
			high += 0x22;
		} else {
			high -= 0xe0;
			high *= 2;
			high += 0x60;
		}

		low -= 0x7e;
	}

	return (high << 8) | low;
}

/* 24bit(12x2) -> 32bit(16x2) */
static	void	decode_kanji(uint8_t *outbuf, uint8_t *inbuf)
{
	int	i, n;

	for (i = 0; i < 6; i++) {
		n = (inbuf[0] << 16) | (inbuf[1] << 8) | inbuf[2];

		outbuf[0] = (n >> 16) & 0xff;
		outbuf[1] = (n >>  8) & 0xf0;
		outbuf[2] = (n >>  4) & 0xff;
		outbuf[3] = (n <<  4) & 0xf0;

		inbuf += 3;
		outbuf += 4;
	}

	return;
}


/* 24bit(6x4) -> 32bit(8x4) */
static	void	decode_ank(uint8_t *outbuf, uint8_t *inbuf)
{
	int	i;
	uint32_t	n;

	for (i = 0; i < 3; i++) {
		n = (inbuf[0] << 16) | (inbuf[1] << 8) | inbuf[2];

		outbuf[0] = (n >> 16) & 0xfc;
		outbuf[1] = (n >> 10) & 0xfc;
		outbuf[2] = (n >>  4) & 0xfc;
		outbuf[3] = (n <<  2) & 0xfc;

		inbuf += 3;
		outbuf += 4;
	}

	return;
}

static	void	convert_kanji(uint8_t *buf)
{
#define	KuTen2Ix(ku, ten)	((ku - 1) * 94 + (ten - 1))

	int	i, j, jis, ku, ten, ix;
	uint8_t	n, d[24];
	FILE	*fp;
	FONTX2_HEADER	h;

	fp = fopen("neko12x12.fnt", "wb");
	if (fp == NULL) goto fin0;

	/* header */
	strncpy(h.identifier, "FONTX2", sizeof(h.identifier));
	strncpy(h.fontname, "NEKOIRAZ", sizeof(h.fontname));
	h.xsize = 12;
	h.ysize = 12;
	h.codetype = CODETYPE_KANJI;
	fwrite(&h, sizeof(h), 1, fp);
	n = sizeof(CodeTable_SJIS1) / sizeof(FONTX2_CODETABLE);
	fputc(n, fp);
	fwrite(CodeTable_SJIS1, sizeof(CodeTable_SJIS1), 1, fp);

	for (i = 0; i < n; i++) {
		for (j = CodeTable_SJIS1[i].start;
		     j <= CodeTable_SJIS1[i].end; j++) {
			jis = _mbcjmstojis(j);
			ku = ((jis >> 8) & 0xff) - 0x20;
			ten = (jis & 0xff) - 0x20;

			ix = KuTen2Ix(ku, ten);

			/* offsetとなる16進数は単純デコードの結果から求める */
			if           (KuTen2Ix(16,  1) <= ix) {	/* 亜〜腕 */
				ix -= KuTen2Ix(16,  1) - 0x3438 / 24;
			} else if    (KuTen2Ix( 7, 49) <= ix) {	/* а〜я */
				ix -= KuTen2Ix( 7, 49) - 0x3030 / 24;
			} else if    (KuTen2Ix( 7,  1) <= ix) {	/* А〜Я */
				ix -= KuTen2Ix( 7,  1) - 0x2d18 / 24;
			} else if    (KuTen2Ix( 6, 33) <= ix) {	/* α〜ω */
				ix -= KuTen2Ix( 6, 33) - 0x2ac0 / 24;
			} else if    (KuTen2Ix( 6,  1) <= ix) {	/* Α〜Ω */
				ix -= KuTen2Ix( 6,  1) - 0x2868 / 24;
			} else if    (KuTen2Ix( 5,  1) <= ix) {	/* ァ〜ヶ */
				ix -= KuTen2Ix( 5,  1) - 0x2058 / 24;
			} else if    (KuTen2Ix( 4,  1) <= ix) {	/* ぁ〜ん */
				ix -= KuTen2Ix( 4,  1) - 0x1818 / 24;
			} else if    (KuTen2Ix( 3, 65) <= ix) {	/* ａ〜ｚ */
				ix -= KuTen2Ix( 3, 65) - 0x15a8 / 24;
			} else if    (KuTen2Ix( 3, 33) <= ix) {	/* Ａ〜Ｚ */
				ix -= KuTen2Ix( 3, 33) - 0x1338 / 24;
			} else if    (KuTen2Ix( 3, 16) <= ix) {	/* ０〜９ */
				ix -= KuTen2Ix( 3, 16) - 0x1248 / 24;
			}

			decode_kanji(d, &buf[ix * 18 + 0x07e0]);
			fwrite(d, sizeof(d), 1, fp);
		}
	}

	fclose(fp);
fin0:
	return;
}

static	void	convert_ank(uint8_t *buf)
{
	int	i;
	uint8_t	d[12];
	FILE	*fp;
	FONTX2_HEADER	h;

	fp = fopen("neko6x12.fnt", "wb");
	if (fp == NULL) goto fin0;

 	/* header */
	strncpy(h.identifier, "FONTX2", sizeof(h.identifier));
	strncpy(h.fontname, "NEKOIRAZ", sizeof(h.fontname));
	h.xsize = 6;
	h.ysize = 12;
	h.codetype = CODETYPE_ASCII;
	fwrite(&h, sizeof(h), 1, fp);

	/* 0x00-0x1f: blank */
	memset(d, 0, sizeof(d));
	for (i = 0x00; i < 0x20; i++) fwrite(d, sizeof(d), 1, fp);

	/* 0x20-0xff */
	for (i = 0x20; i < 0x100; i++) {
		decode_ank(d, &buf[(i - 0x20) * 9]);
		fwrite(d, sizeof(d), 1, fp);
	}

	fclose(fp);
fin0:
	return;
}

static	int	bload(char *filename, uint8_t *buf, int size)
{
	int	result;
	FILE	*fp;

	fp = fopen(filename, "rb");
	if (fp == NULL) {
		result = -1;
		goto fin0;
	}

	fread(buf, 1, 7, fp);	/* discard BSAVE header */
	fread(buf, 1, size, fp);
	fclose(fp);

	result = 0;
fin0:
	return result;
}

int	main(int argc, char *argv[])
{
	if (bload("kanji3.grp", Buf, 65419) < 0) {
		printf("kanji3.grp not found\n");
		goto fin0;
	}
	convert_ank(Buf);
	convert_kanji(Buf);

fin0:
	return 0;
}