/*
 * Copyright (c) 2006 OpenedHand Ltd.
 *
 * This file is licensed under GNU GPL v2.
 */
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>

#define TFR(_)		_
#define VERBOSE
#define PBAR_LEN	40

#define PARTITION_START	0x00700000

static const int ecc_pos8[] = {
	0x0, 0x1, 0x2,
};

static const int ecc_pos16[] = {
	0x0, 0x1, 0x2, 0x3, 0x6, 0x7,
};

static const int ecc_pos64[] = {
	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
};

static const int ecc_akita[] = {
	0x05, 0x01, 0x02, 0x03, 0x06, 0x07, 0x15, 0x11,
	0x12, 0x13, 0x16, 0x17, 0x25, 0x21, 0x22, 0x23,
	0x26, 0x27, 0x35, 0x31, 0x32, 0x33, 0x36, 0x37,
};

struct jffs_marker_s {
	int pos;
	uint8_t value;
};

static const struct jffs_marker_s free_pos8[] = {
	{ 0x03, 0xff }, { 0x04, 0xff }, { 0x06, 0x85 }, { 0x07, 0x19 },
	{ -1 },
};

static const struct jffs_marker_s free_pos16[] = {
	{ 0x08, 0x85 }, { 0x09, 0x19 }, { 0x0a, 0x03 }, { 0x0b, 0x20 },
	{ 0x0c, 0x08 }, { 0x0d, 0x00 }, { 0x0e, 0x00 }, { 0x0f, 0x00 },
	{ -1 },
};

static const struct jffs_marker_s free_pos64[] = {
	{ 0x02, 0xff }, { 0x03, 0xff }, { 0x04, 0xff }, { 0x05, 0xff },
	{ 0x06, 0xff }, { 0x07, 0xff }, { 0x08, 0xff }, { 0x09, 0xff },
	{ 0x0a, 0xff }, { 0x0b, 0xff }, { 0x0c, 0xff }, { 0x0d, 0xff },
	{ 0x0e, 0xff }, { 0x0f, 0xff }, { 0x10, 0x85 }, { 0x11, 0x19 },
	{ 0x12, 0x03 }, { 0x13, 0x20 }, { 0x14, 0x08 }, { 0x15, 0x00 },
	{ 0x16, 0x00 }, { 0x17, 0x00 }, { 0x18, 0xff }, { 0x19, 0xff },
	{ 0x1a, 0xff }, { 0x1b, 0xff }, { 0x1c, 0xff }, { 0x1d, 0xff },
	{ 0x1e, 0xff }, { 0x1f, 0xff }, { 0x20, 0xff }, { 0x21, 0xff },
	{ 0x22, 0xff }, { 0x23, 0xff }, { 0x24, 0xff }, { 0x25, 0xff },
	{ 0x26, 0xff }, { 0x27, 0xff },
	{ -1 },
};

static const struct jffs_marker_s free_akita[] = {
	{ 0x08, 0x85 }, { 0x09, 0x19 }, { 0x0a, 0x03 }, { 0x0b, 0x20 },
	{ 0x0c, 0x08 }, { 0x0d, 0x00 }, { 0x0e, 0x00 }, { 0x0f, 0x00 },
	{ 0x10, 0xff },
	{ -1 },
};

#define LEN(array)	(sizeof(array) / sizeof(*array))

static const struct ecc_style_s {
	int page_size;
	int oob_size;
	int eccbytes;
	int eccsize;
	const int *eccpos;
	int romsize;
	const struct jffs_marker_s *freepos;
} spitz = {
	0x200, 0x10, 0x100, LEN(ecc_pos16), ecc_pos16, 0x01000000, free_pos16
}, akita = {
	0x800, 0x40, 0x100, LEN(ecc_akita), ecc_akita, 0x08000000, free_akita
}, borzoi = {
	0x800, 0x40, 0x100, LEN(ecc_akita), ecc_akita, 0x08000000, free_akita
}, terrier = {
	0x800, 0x40, 0x100, LEN(ecc_akita), ecc_akita, 0x08000000, free_akita
};

struct ecc_state_s {
	int count;
	uint8_t cp;
	uint8_t lp[2];
	const struct ecc_style_s *style;
};

#ifndef flash2raw
/*
 * Pre-calculated 256-way 1 byte column parity.  Table borrowed from Linux.
 */
static const uint8_t ecc_precalc_table[] = {
	0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a,
	0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
	0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f,
	0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
	0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c,
	0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
	0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59,
	0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
	0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33,
	0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
	0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56,
	0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
	0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55,
	0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
	0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30,
	0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
	0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30,
	0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
	0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55,
	0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
	0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56,
	0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
	0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33,
	0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
	0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59,
	0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
	0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c,
	0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
	0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f,
	0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
	0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a,
	0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
};

/* Update ECC parity count */
static inline uint8_t ecc_digest(struct ecc_state_s *s, uint8_t sample) {
	uint8_t idx = ecc_precalc_table[sample];

	s->cp ^= idx & 0x3f;
	if (idx & 0x40) {
		s->lp[0] ^= ~(s->count & 0xff);
		s->lp[1] ^= s->count & 0xff;
	}
	s->count ++;

	return sample;
}

static void buffer_digest(struct ecc_state_s *ecc,
		const uint8_t *buf, uint8_t *out) {
	int i, lp_a[2];

	ecc->lp[0] = 0x00;
	ecc->lp[1] = 0x00;
	ecc->cp = 0x00;
	ecc->count = 0;
	for (i = 0; i < ecc->style->eccbytes; i ++)
		ecc_digest(ecc, buf[i]);

# define BSHR(byte, from, to)	((ecc->lp[byte] >> (from - to)) & (1 << to))
	lp_a[0] =
		BSHR(0, 4, 0) | BSHR(0, 5, 2) |
		BSHR(0, 6, 4) | BSHR(0, 7, 6) |
		BSHR(1, 4, 1) | BSHR(1, 5, 3) |
		BSHR(1, 6, 5) | BSHR(1, 7, 7);

# define BSHL(byte, from, to)	((ecc->lp[byte] << (to - from)) & (1 << to))
	lp_a[1] =
		BSHL(0, 0, 0) | BSHL(0, 1, 2) |
		BSHL(0, 2, 4) | BSHL(0, 3, 6) |
		BSHL(1, 0, 1) | BSHL(1, 1, 3) |
		BSHL(1, 2, 5) | BSHL(1, 3, 7);

	out[0] = ~lp_a[1];
	out[1] = ~lp_a[0];
	out[2] = (~ecc->cp << 2) | 0x03;
}

static void jffs2_format(const struct ecc_state_s *ecc, uint8_t oob[]) {
	const struct jffs_marker_s *byte;
	for (byte = ecc->style->freepos; byte->pos >= 0; byte ++)
		oob[byte->pos] = byte->value;
}

static void buffer_fill(const struct ecc_state_s *ecc, uint8_t buffer[],
		int *len, int *partition, int count, uint8_t jffs_buffer[]) {
	int ret;

	switch (*partition) {
	case 0:
		if (count < PARTITION_START) {
			memcpy(buffer, jffs_buffer + count,
					ecc->style->eccbytes);
			*len = ecc->style->eccbytes;
			break;
		}
		*partition = 1;
	case 1:
		if (count - PARTITION_START < PARTITION_START) {
			memcpy(buffer, jffs_buffer + count - PARTITION_START,
					ecc->style->eccbytes);
			*len = ecc->style->eccbytes;
			break;
		}

		while (*len < ecc->style->eccbytes) {
			ret = TFR(read(0, buffer + *len, 0x800 - *len));
			if (ret <= 0)
				break;
			*len += ret;
		}

		if (*len == 0)
			*partition = 2;
		else if (*len < ecc->style->eccbytes) {
			fprintf(stderr, "\nWarning: %i stray bytes\n", *len);
			memset(buffer + *len, 0xff,
					ecc->style->eccbytes - *len);
			*len = ecc->style->eccbytes;
			break;
		} else
			break;
	case 2:
		memset(buffer, 0xff, ecc->style->eccbytes);
		*len = ecc->style->eccbytes;
		break;
	}
}

int main(int argc, char *argv[], char *envp[]) {
	struct ecc_state_s ecc;
	uint8_t buffer[0x1000], ecc_payload[0x40], regs[3], *jffs;
	int ret, len, eccbyte, count, partition;

	/* Check if we're called by "raw2flash.spitz" or similar */
	len = strlen(argv[0]);
	if (!strcasecmp(argv[0] + len - 5, "akita"))
		ecc.style = &akita;
	else if (!strcasecmp(argv[0] + len - 6, "borzoi"))
		ecc.style = &borzoi;
	else if (!strcasecmp(argv[0] + len - 7, "terrier"))
		ecc.style = &terrier;
	else
		ecc.style = &spitz;

# ifdef VERBOSE
	fprintf(stderr, "[");
# endif

	/* Skip first 10 bytes */
	TFR(read(0, buffer, 0x10));

	len = 0;
	jffs = (uint8_t *) malloc(PARTITION_START);
	while (len < PARTITION_START) {
		ret = TFR(read(0, jffs + len, PARTITION_START - len));
		if (ret <= 0)
			break;
		len += ret;
	}

	/* Convert data from stdin */
	partition = len = eccbyte = count = 0;
	memset(ecc_payload, 0xff, ecc.style->oob_size);
	jffs2_format(&ecc, ecc_payload);
	while (count < ecc.style->romsize) {
		buffer_fill(&ecc, buffer, &len, &partition, count, jffs);
		buffer_digest(&ecc, buffer, regs);

		ecc_payload[ecc.style->eccpos[eccbyte ++]] = regs[0];
		ecc_payload[ecc.style->eccpos[eccbyte ++]] = regs[1];
		ecc_payload[ecc.style->eccpos[eccbyte ++]] = regs[2];

		TFR(write(1, buffer, ecc.style->eccbytes));
		count += ecc.style->eccbytes;
		len -= ecc.style->eccbytes;
		memmove(buffer, buffer + ecc.style->eccbytes, len);

		if (eccbyte >= ecc.style->eccsize) {
			TFR(write(1, ecc_payload, ecc.style->oob_size));
			eccbyte = 0;
			memset(ecc_payload, 0xff, ecc.style->oob_size);
			if (partition < 2)
				jffs2_format(&ecc, ecc_payload);
		}

# ifdef VERBOSE
		if (count * PBAR_LEN / ecc.style->romsize >
				(count - ecc.style->eccbytes) *
				PBAR_LEN / ecc.style->romsize)
			fprintf(stderr, "#");
# endif
	}

# ifdef VERBOSE
	fprintf(stderr, "]\n");
# endif
	free(jffs);
	return 0;
}
#else
int main(int argc, char *argv[], char *envp[]) {
	struct ecc_state_s ecc;
	uint8_t buffer[0x1000];
	int ret, len, count;

	/* Check if we're called by "flash2raw.spitz" or similar */
	len = strlen(argv[0]);
	if (!strcasecmp(argv[0] + len - 5, "akita"))
		ecc.style = &akita;
	else if (!strcasecmp(argv[0] + len - 6, "borzoi"))
		ecc.style = &borzoi;
	else if (!strcasecmp(argv[0] + len - 7, "terrier"))
		ecc.style = &terrier;
	else
		ecc.style = &spitz;

# ifdef VERBOSE
	fprintf(stderr, "[");
# endif

	/* Convert data from stdin */
	count = 0;
	while (count < ecc.style->romsize) {
		len = 0;
		while (len < ecc.style->page_size) {
			ret = TFR(read(0, buffer + len,
						ecc.style->page_size - len));
			if (ret <= 0)
				break;
			len += ret;
		}
		if (len == 0)
			break;
		if (len < ecc.style->page_size) {
			fprintf(stderr, "\nWarning: %i stray bytes\n", len);
		}

		TFR(write(1, buffer, ecc.style->page_size));

		count += len;
		len = 0;
		while (len < ecc.style->oob_size) {
			ret = TFR(read(0, buffer, ecc.style->oob_size - len));
			if (ret <= 0)
				break;
			len += ret;
		}

# ifdef VERBOSE
		if (count * PBAR_LEN / ecc.style->romsize >
				(count - ecc.style->page_size) *
				PBAR_LEN / ecc.style->romsize)
			fprintf(stderr, "#");
# endif
	}

# ifdef VERBOSE
	fprintf(stderr, "]\n");
# endif
	return 0;
}
#endif