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/*
 * Copyright (C) 2010 by David Brownell
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Simple utility to parse and dump ARM Cortex-M3 SWO trace output.  Once the
 * mechanisms work right, this information can be used for various purposes
 * including profiling (particularly easy for flat PC-sample profiles) and
 * for debugging.
 *
 * SWO is the Single Wire Output found on some ARM cores, most notably on the
 * Cortex-M3.  It combines data from several sources:
 *
 *  - Software trace (ITM):  so-called "printf-style" application messaging
 *    using "ITM stimulus ports"; and differential timestamps.
 *  - Hardware trace (DWT):  for profiling counters and comparator matches.
 *  - TPIU may issue sync packets.
 *
 * The trace data format is defined in Appendix E, "Debug ITM and DWT packet
 * protocol", of the ARMv7-M Architecture Reference Manual (DDI 0403C).  It
 * is a superset of the ITM data format from the Coresight TRM.
 *
 * The trace data has two encodings.  The working assumption is that data
 * gets into this program using the UART encoding.
 */

#include <errno.h>
#include <libgen.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>

unsigned int dump_swit;

/* Example ITM trace word (0xWWXXYYZZ) parsing for task events, sent
 * on port 31 (Reserved for "the" RTOS in CMSIS v1.30)
 *   WWXX: event code (0..3 pre-assigned, 4..15 reserved)
 *   YY:   task priority
 *   ZZ:   task number
 *
 * NOTE that this specific encoding could be space-optimized; and that
 * trace data streams could also be history-sensitive.
 */
static void show_task(int port, unsigned data)
{
	unsigned code = data >> 16;
	char buf[16];

	if (dump_swit)
		return;

	switch (code) {
	case 0:
		strcpy(buf, "run");
		break;
	case 1:
		strcpy(buf, "block");
		break;
	case 2:
		strcpy(buf, "create");
		break;
	case 3:
		strcpy(buf, "destroy");
		break;
	/* 4..15 reserved for other infrastructure ops */
	default:
		sprintf(buf, "code %d", code);
		break;
	}
	printf("TASK %d, pri %d: %s",
		(data >> 0) & 0xff,
		(data >> 8) & 0xff,
		buf);
}

static void show_reserved(FILE *f, char *label, int c)
{
	unsigned i;

	if (dump_swit)
		return;

	printf("%s - %#02x", label, c);

	for (i = 0; (c & 0x80) && i < 4; i++) {
		c = fgetc(f);
		if (c == EOF) {
			printf("(ERROR %d - %s) ", errno, strerror(errno));
			break;
		}
		printf(" %#02x", c);
	}

	printf("\n");
}

static bool read_varlen(FILE *f, int c, unsigned *value)
{
	unsigned size;
	unsigned char buf[4];

	*value = 0;

	switch (c & 3) {
	case 3:
		size = 4;
		break;
	case 2:
		size = 2;
		break;
	case 1:
		size = 1;
		break;
	default:
		printf("INVALID SIZE\n");
		return false;
	}

	memset(buf, 0, sizeof buf);
	if (fread(buf, 1, size, f) != size)
		goto err;

	*value =  (buf[3] << 24)
		+ (buf[2] << 16)
		+ (buf[1] << 8)
		+ (buf[0] << 0);
	return true;

err:
	printf("(ERROR %d - %s)\n", errno, strerror(errno));
	return false;
}

static void show_hard(FILE *f, int c)
{
	unsigned type = c >> 3;
	unsigned value;
	char *label;

	if (dump_swit)
		return;

	printf("DWT - ");

	if (!read_varlen(f, c, &value))
		return;
	printf("%#x", value);

	switch (type) {
	case 0:				/* event counter wrapping */
		printf("overflow %s%s%s%s%s%s",
			(value & (1 << 5)) ? "cyc " : "",
			(value & (1 << 4)) ? "fold " : "",
			(value & (1 << 3)) ? "lsu " : "",
			(value & (1 << 2)) ? "slp " : "",
			(value & (1 << 1)) ? "exc " : "",
			(value & (1 << 0)) ? "cpi " : "");
		break;
	case 1:				/* exception tracing */
		switch (value >> 12) {
		case 1:
			label = "entry to";
			break;
		case 2:
			label = "exit from";
			break;
		case 3:
			label = "return to";
			break;
		default:
			label = "?";
			break;
		}
		printf("%s exception %d", label, value & 0x1ff);
		break;
	case 2:				/* PC sampling */
		if (c == 0x15)
			printf("PC - sleep");
		else
			printf("PC - %#08x", value);
		break;
	case 8:				/* data tracing, pc value */
	case 10:
	case 12:
	case 14:
		printf("Data trace %d, PC %#08x", (c >> 4) & 3, value);
		/* optionally followed by data value */
		break;
	case 9:				/* data tracing, address offset */
	case 11:
	case 13:
	case 15:
		printf("Data trace %d, address offset %#04x",
				(c >> 4) & 3, value);
		/* always followed by data value */
		break;
	case 16 ... 23:			/* data tracing, data value */
		printf("Data trace %d, ", (c >> 4) & 3);
		label = (c & 0x8) ? "write" : "read";
		switch (c & 3) {
		case 3:
			printf("word %s, value %#08x", label, value);
			break;
		case 2:
			printf("halfword %s, value %#04x", label, value);
			break;
		case 1:
			printf("byte %s, value %#02x", label, value);
			break;
		}
		break;
	default:
		printf("UNDEFINED, rawtype: %x", type);
		break;
	}

	printf("\n");
	return;
}

/*
 * Table of SWIT (SoftWare InstrumentTation) message dump formats, for
 * ITM port 0..31 application data.
 *
 * Eventually this should be customizable; all usage is application defined.
 *
 * REVISIT there can be up to 256 trace ports, via "ITM Extension" packets
 */
struct {
	int port;
	void (*show)(int port, unsigned data);
} format[] = {
	{ .port = 31,  .show = show_task, },
};

static void show_swit(FILE *f, int c)
{
	unsigned port = c >> 3;
	unsigned value = 0;
	unsigned i;

	if (port + 1 == dump_swit) {
		if (!read_varlen(f, c, &value))
			return;
		printf("%c", value);
		return;
	}

	if (!read_varlen(f, c, &value))
		return;

	if (dump_swit)
		return;

	printf("SWIT %u - ", port);

	printf("%#08x", value);

	for (i = 0; i < sizeof(format) / sizeof(format[0]); i++) {
		if (format[i].port == port) {
			printf(", ");
			format[i].show(port, value);
			break;
		}
	}

	printf("\n");
	return;
}

static void show_timestamp(FILE *f, int c)
{
	unsigned counter = 0;
	char *label = "";
	bool delayed = false;

	if (dump_swit)
		return;