// Copyright (c) 2013-2019 Bluespec, Inc.  All Rights Reserved

// ================================================================
// These are functions imported into BSV during Bluesim or Verilog simulation.
// See C_Imports.bsv for the corresponding 'import BDPI' declarations.

// There are several independent groups of functions below; the
// groups are separated by heavy dividers ('// *******')

// Below, 'dummy' args are not used, and are present only to appease
// some Verilog simulators that are finicky about 0-arg functions.

// ================================================================
// Includes from C library

// General
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <inttypes.h>
#include <string.h>
#include <errno.h>

// For comms polling
#include <sys/types.h>
#include <poll.h>
#include <sched.h>

// For TCP
#include <sys/socket.h>       //  socket definitions
#include <sys/types.h>        //  socket types
#include <arpa/inet.h>        //  inet (3) funtions
#include <fcntl.h>            // To set non-blocking mode

// ================================================================
// Includes for this project

#include "C_Imported_Functions.h"

// ****************************************************************
// ****************************************************************
// ****************************************************************

// Functions for console I/O

// ================================================================
// c_trygetchar()
// Returns next input character (ASCII code) from the console.
// Returns 0 if no input is available.

uint8_t c_trygetchar (uint8_t  dummy)
{
    uint8_t  ch;
    ssize_t  n;
    struct pollfd  x_pollfd;
    const int fd_stdin = 0;

    // ----------------
    // Poll for input
    x_pollfd.fd      = fd_stdin;
    x_pollfd.events  = POLLRDNORM;
    x_pollfd.revents = 0;
    poll (& x_pollfd, 1, 1);

    // printf ("INFO: c_trygetchar: Polling for input\n");
    if ((x_pollfd.revents & POLLRDNORM) == 0) {
	return 0;
    }

    // ----------------
    // Input is available

    n = read (fd_stdin, & ch, 1);
    if (n == 1) {
	return ch;
    }
    else {
	if (n == 0)
	    printf ("c_trygetchar: end of file\n");
	return 0xFF;
    }
}

// ================================================================
// A small 'main' to test c_trygetchar()

#ifdef TEST_TRYGETCHAR

char message[] = "Hello World!\n";

int main (int argc, char *argv [])
{
    uint8_t ch;
    int j;

    for (j = 0; j < strlen (message); j++)
	c_putchar (message[j]);

    printf ("Polling for input\n");

    j = 0;
    while (1) {
	ch = c_trygetchar ();
	if (ch == 0xFF) break;
	if (ch != 0)
	    printf ("Received character %0d 0x%0x '%c'\n", ch, ch, ch);
	else {
	    printf ("\r%0d ", j);
	    fflush (stdout);
	    j++;
	    sleep (1);
	}
    }
    return 0;
}

#endif

// ================================================================
// c_putchar()
// Writes character to stdout

uint32_t c_putchar (uint8_t ch)
{
    int      status;
    uint32_t success = 0;

    if ((ch == 0) || (ch > 0x7F)) {
	// Discard non-printables
	success = 1;
    }
    else {
	if ((ch == '\n') || (' ' <= ch)) {
	    status = fprintf (stdout, "%c", ch);
	    if (status > 0)
		success = 1;
	}
	else {
	    status = fprintf (stdout, "[\\%0d]", ch);
	    if (status > 0)
		success = 1;
	}

	if (success == 1) {
	    status = fflush (stdout);
	    if (status != 0)
		success = 0;
	}
    }

    return success;
}

// ****************************************************************
// ****************************************************************
// ****************************************************************

// Functions for reading in various parameters

// ================================================================
// c_get_symbol_val ()
// Returns the value of a symbol (a memory address) from a symbol-table file.
// The symbol-table file has a '<symbol> <value-in-hex>' pair on each line.
// Reads the whole symbol-table file on each call,
// which is ok if it's not called often and the file is small.

static
char symbol_table_filename [] = "symbol_table.txt";

uint64_t c_get_symbol_val (char * symbol)
{
    bool     ok  = false;
    uint64_t val = 0;

    FILE *fp = fopen (symbol_table_filename, "r");
    if (fp == NULL) {
	fprintf (stderr, "c_get_symbol: could not open file: %s\n", symbol_table_filename);
    }
    else {
	int len     = strlen (symbol);
	int linenum = 0;

	while (true) {
	    char linebuf [1024], *p;
	    p = fgets (linebuf, 1024, fp);
	    if (p == NULL) {   // EOF
		fprintf (stderr, "c_get_symbol: could not find value for symbol %s\n", symbol);
		break;
	    }
	    else {
		linenum++;

		int cmp = strncmp (symbol, linebuf, len);
		if (cmp != 0)    // This symbol is not on this line
		    continue;
		else {
		    int n = sscanf (& (linebuf [len]), "%" SCNx64, & val);
		    if ((n == EOF) || (n < 1)) {
			fprintf (stderr, "c_get_symbol: could not find value for symbol %s\n", symbol);
			fprintf (stderr, "    on file '%s' line %d\n", symbol_table_filename, linenum);
		    }
		    else
			ok = true;
		    break;
		}
	    }
	}
    }
    return val;
}

// ----------------------------------------------------------------
// A small 'main' to test c_get_symbol_val()

#ifdef TEST_GET_SYMBOL_VAL

int main (int argc, char *argv [])
{
  uint64_t x = c_get_symbol_val ("tohost");
    fprintf (stdout, "tohost value is 0x%" PRIx64 "\n", x);
}

#endif

// ================================================================
// Misc. parameters from a parameters file, if it exists.
// Each non-empty line of the file should contain
//     param-name  param-value  comment
// or  # comment

/*
#define MAX_PARAMS  128

char   sim_params_filename[] = "sim_params.txt";
static bool      params_loaded = false;
static uint64_t  param_vals [MAX_PARAMS];

#define PARAM_LINEBUF_SIZE 1024

static
void load_params (void)
{
    for (uint32_t j = 0; j < MAX_PARAMS; j++)
	param_vals [j] = 0;

    FILE *fp = fopen ("sim_params.txt", "r");
    if (fp == NULL) {
	fprintf (stdout, "INFO: no simulation parameters file: %s\n", sim_params_filename);
	return;
    }
    else {
	fprintf (stdout, "INFO: loading simulation parameters from file: %s\n", sim_params_filename);
    }

    while (true) {
	char     linebuf [PARAM_LINEBUF_SIZE], *p;

	p = fgets (linebuf, PARAM_LINEBUF_SIZE, fp);
	if (p == NULL)    // EOF
	    break;

	// Skip leading blanks and tabs
	int index = 0;
	while ((index < PARAM_LINEBUF_SIZE)
	       && ((linebuf [index] == ' ') || (linebuf [index] == '\t')))
	    index++;
	if (index == PARAM_LINEBUF_SIZE)
	    break;

	if (linebuf [index] == '#')  // comment line
	    continue;

	// Read the parameter code
	uint32_t param;
	int n = sscanf (& linebuf [index], "%" SCNd32 "%n", & param, & index);
	if ((n == EOF) || (n < 1))
	    continue;

	// Read the parameter value (decimal or hex, depending on the parameter)
	uint64_t param_val;
	if (param == sim_param_watch_tohost) {
	    int n = sscanf (& (linebuf [index]), "%" SCNd64, & param_val);
	}
	else if (param == sim_param_tohost_addr) {
	    int n = sscanf (& (linebuf [index]), "%" SCNx64, & param_val);
	}
	else {
	    int n = sscanf (& (linebuf [index]), "%" SCNd64, & param_val);
	}

	if ((n == EOF) || (n < 1))
	    continue;
	else if (param >= MAX_PARAMS) {
	    fprintf (stderr, "INFO: ignoring out-of-bounds parameter code %0" PRId32 " (should be < %0d)\n",
		     param, MAX_PARAMS);
	    fprintf (stderr, "    Value (decimal) = %0" PRId64, param_val);
	    fprintf (stderr, "    Value (hex)     = 0x%0" PRIx64, param_val);
	}
	else {
	    param_vals [param] = param_val;
	}
    }
    fclose (fp);
}

uint64_t c_get_param_val (uint32_t  param)
{
    if (! params_loaded) {
	load_params ();
	params_loaded = true;
    }

    uint64_t param_val = 0;
    if (param < MAX_PARAMS)
	param_val = param_vals [param];
    return param_val;
}

*/

// ****************************************************************
// ****************************************************************
// ****************************************************************

// Functions for Tandem Verification trace file output.

static char trace_file_name[] = "trace_data.dat";

static FILE *trace_file_stream;

static uint64_t trace_file_size   = 0;
static uint64_t trace_file_writes = 0;

#define BUFSIZE 1024
static uint8_t buf [BUFSIZE];

// ================================================================
// c_trace_file_open()
// Open file for recording binary trace output.

uint32_t c_trace_file_open (uint8_t dummy)
{
    uint32_t success = 0;

    trace_file_stream = fopen ("trace_out.dat", "w");
    if (trace_file_stream == NULL) {
	fprintf (stderr, "ERROR: c_trace_file_open: unable to open file '%s'.\n", trace_file_name);
	success = 0;
    }
    else {
	fprintf (stdout, "c_trace_file_stream: opened file '%s' for trace_data.\n", trace_file_name);
	success = 1;
    }
    return success;
}

// ================================================================
// c_trace_file_load_byte_in_buffer ()
// Write 8-bit 'data' into output buffer at byte offset 'j'

uint32_t c_trace_file_load_byte_in_buffer (uint32_t j, uint8_t data)
{
    uint32_t success = 0;

    if (j >= BUFSIZE) {
	fprintf (stderr, "ERROR: c_trace_file_load_byte_in_buffer: index (%0d) out of bounds (%0d)\n",
		 j, BUFSIZE);
	success = 0;
    }
    else {
	buf [j] = data;
	success = 1;
    }
    return success;
}

// ================================================================
// c_trace_file_load_word64_in_buffer ()
// Write 64-bit 'data' into output buffer at 'byte_offset'

uint32_t c_trace_file_load_word64_in_buffer (uint32_t byte_offset, uint64_t data)
{
    uint32_t success = 0;

    if ((byte_offset + 7) >= BUFSIZE) {
	fprintf (stderr, "ERROR: c_trace_file_load_word64_in_buffer: index (%0d) out of bounds (%0d)\n",
		 byte_offset, BUFSIZE);
	success = 0;
    }
    else {
	uint64_t *p = (uint64_t *) & (buf [byte_offset]);
	*p = data;
	success = 1;
    }
    return success;
}

// ================================================================
// c_trace_file_write_buffer()
// Write out 'n' bytes from the already-loaded output buffer to the trace file.

uint32_t c_trace_file_write_buffer (uint32_t n)
{
    uint32_t success = 0;

    size_t n_written = fwrite (buf, 1, n, trace_file_stream);
    if (n_written != n)
	success = 0;
    else {
	trace_file_size   += n;
	trace_file_writes += 1;
	success = 1;
    }
    return success;
}

// ================================================================
// c_trace_file_close()
// Close the trace file.

uint32_t c_trace_file_close (uint8_t dummy)
{
    uint32_t success = 0;
    int      status;

    if (trace_file_stream == NULL)
	success = 1;
    else {
	status = fclose (trace_file_stream);
	if (status != 0) {
	    fprintf (stderr, "ERROR: c_trace_file_close: error in fclose()\n");
	    success = 0;
	}
	else {
	    fprintf (stdout, "c_trace_file_stream: closed file '%s' for trace_data.\n", trace_file_name);
	    fprintf (stdout, "    Trace file writes: %0" PRId64 "\n", trace_file_writes);
	    fprintf (stdout, "    Trace file size:   %0" PRId64 " bytes\n", trace_file_size);
	    success = 1;
	}
    }
    return success;
}

// ****************************************************************
// ****************************************************************
// ****************************************************************

// Functions for communication with remote debug client.

// Acknowledgement: portions of TCP code adapted from example ECHOSERV
//   ECHOSERV
//   (c) Paul Griffiths, 1999
//   http://www.paulgriffiths.net/program/c/echoserv.php

// ================================================================
// The socket file descriptor

static uint16_t port = 30000;

static int connected_sockfd = 0;

static FILE *logfile_fp = NULL;

static char logfile_name [] = "debug_server_log.txt";

// ================================================================
// Connect to debug client as server on tcp_port.
// Return fail/ok.

uint8_t  c_debug_client_connect (const uint16_t tcp_port)
{
    int                 listen_sockfd;        // listening socket
    struct sockaddr_in  servaddr;             // socket address structure
    struct linger       linger;
  
    fprintf (stdout, "Awaiting remote debug client connection on tcp port %0d ...\n", tcp_port);

    // Create the listening socket
    if ( (listen_sockfd = socket (AF_INET, SOCK_STREAM, 0)) < 0 ) {
	fprintf (stderr, "ERROR: c_debug_client_connect: socket () failed\n");
	return DMI_STATUS_ERR;
    }
  
    // Set linger to 0 (immediate exit on close)
    linger.l_onoff  = 1;
    linger.l_linger = 0;
    setsockopt (listen_sockfd, SOL_SOCKET, SO_LINGER, & linger, sizeof (linger));

    // Initialize socket address structure
    memset (& servaddr, 0, sizeof (servaddr));
    servaddr.sin_family      = AF_INET;
    servaddr.sin_addr.s_addr = htonl (INADDR_ANY);
    servaddr.sin_port        = htons (tcp_port);

    // Bind socket addresss to listening socket
    if ( bind (listen_sockfd, (struct sockaddr *) & servaddr, sizeof (servaddr)) < 0 ) {
	fprintf (stderr, "ERROR: c_debug_client_connect: bind () failed\n");
	return DMI_STATUS_ERR;
    }

    // Listen for connection
    if ( listen (listen_sockfd, 1) < 0 ) {
	fprintf (stderr, "ERROR: c_debug_client_connect: listen () failed\n");
	return DMI_STATUS_ERR;
    }

    // Set listening socket to non-blocking
    int flags = fcntl (listen_sockfd, F_GETFL, 0);
    if (flags < 0) {
	fprintf (stderr, "ERROR: c_debug_client_connect: fcntl (F_GETFL) failed\n");
	return DMI_STATUS_ERR;
    }
    flags = (flags |O_NONBLOCK);
    if (fcntl (listen_sockfd, F_SETFL, flags) < 0) {
	fprintf (stderr, "ERROR: c_debug_client_connect: fcntl (F_SETFL, O_NONBLOCK) failed\n");
	return DMI_STATUS_ERR;
    }

    // Wait for a connection, accept() it
    while (true) {
	connected_sockfd = accept (listen_sockfd, NULL, NULL);
	if ((connected_sockfd < 0) && ((errno == EAGAIN) || (errno == EWOULDBLOCK))) {
	    sleep (1);
	}
	else if (connected_sockfd < 0) {
	    fprintf (stderr, "ERROR: c_debug_client_connect: accept () failed\n");
	    return DMI_STATUS_ERR;
	}
	else
	    break;
    }

    // Close the listening socket
    if (close (listen_sockfd) < 0) {
	perror ("ERROR: c_debug_client_connect: error in close (listen_sockfd)");
	return DMI_STATUS_ERR;
    }

    fprintf (stdout, "Connected\n");

    logfile_fp = fopen (logfile_name, "w");
    if (logfile_fp != NULL) {
	fprintf (stdout, "    Logfile for debug client transactions is '%s'\n", logfile_name);
	fprintf (logfile_fp, "CONNECTED on TCP port %0d\n", tcp_port);
    }
    else
	fprintf (stdout, "    Unable to open logfile for debug client transactions: '%s'\n",
		 logfile_name);

    return DMI_STATUS_OK;
}

// ================================================================
// Disconnect from debug client as server.
// Return fail/ok.

uint8_t c_debug_client_disconnect (uint8_t dummy)
{
    uint8_t buf [128];
    ssize_t n;

    fprintf (stdout, "Disconnected from remote debug client on port %0d\n", port);

    shutdown (connected_sockfd, SHUT_WR);

    // Drain remaining bytes arriving
    while (1) {
	n = recv (connected_sockfd, buf, 128, 0);
	if (n == 0)
	    break;
	if ((n == -1) && (errno != EINTR))
	    break;
    }

    if (close (connected_sockfd) < 0) {
	perror ("ERROR: c_debug_client_disconnect:");
	fprintf (stderr, "    socket file descriptor: %0d\n", connected_sockfd);
	return DMI_STATUS_ERR;
    }

    if (logfile_fp != NULL) {
	fprintf (logfile_fp, "DISCONNECTED on port %0d\n", port);
	fclose (logfile_fp);
    }

    return DMI_STATUS_OK;
}

// ================================================================
// Receive 7-byte request from remote client
// Result is:    { status, data_b3, data_b2, data_b1, data_b0, addr_b1, addr_b0, op }

static int command_num = 0;

uint64_t c_debug_client_request_recv (uint8_t dummy)
{
    uint64_t  result   = 0;
    uint8_t  *p_result = (uint8_t *) & result;

    // ----------------
    // First, poll to check if any data is available
    int fd = connected_sockfd;

    struct pollfd  x_pollfd;
    x_pollfd.fd      = fd;
    x_pollfd.events  = POLLRDNORM;
    x_pollfd.revents = 0;

    int n = poll (& x_pollfd, 1, 0);

    if (n < 0) {
	perror ("ERROR: c_debug_client_request_recv (): poll () failed");
	p_result [7] = DMI_STATUS_ERR;
	return result;
    }

    if ((x_pollfd.revents & POLLRDNORM) == 0) {
	// No byte available
	// sched_yield ();    // Allow other threads to run.
	p_result [7] = DMI_STATUS_UNAVAIL;
	return result;
    }

    // ----------------
    // Data is available; read the 7-byte request

    int  data_size = 7;
    int  n_recd    = 0;
    int  n_iters   = 0;
    p_result [0] = DMI_STATUS_ERR;
    while (n_recd < data_size) {
	int n = read (fd, p_result + n_recd, (data_size - n_recd));
	if ((n < 0) && (errno != EAGAIN) && (errno != EWOULDBLOCK)) {
	    if (logfile_fp != NULL) {
		fprintf (logfile_fp, "ERROR: c_debug_client_request_recv () failed\n");
		fprintf (logfile_fp, "    Received %0d bytes so far (of %0d)\n", n_recd, data_size);
		fprintf (logfile_fp, "    Data so far: 0x%0" PRIx64 "\n", result);
		fprintf (logfile_fp, "    read (sock, ...) => %0d\n", n);
	    }
	    p_result [7] = DMI_STATUS_ERR;
	    return result;
	}
	else if (n > 0) {
	    n_recd += n;
	}

	n_iters++;
	if ((n_iters > 0) && ((n_iters % 1000000) == 0)) {
	    if (logfile_fp != NULL) {
		fprintf (logfile_fp, "WARNING: c_debug_client_request_recv () stalled?\n");
		fprintf (logfile_fp, "    Received %0d bytes so far (of %0d)\n", n_recd, data_size);
		fprintf (logfile_fp, "    Data so far: 0x%0" PRIx64 "\n", result);
		fprintf (logfile_fp, "    %0d iterations so far\n", n_iters);
	    }
	}
    }
    p_result [7] = DMI_STATUS_OK;

    if (logfile_fp != NULL) {
	uint8_t  op   = (result         & 0xFF);
	uint16_t addr = ((result >> 8)  & 0xFFFF);
	uint32_t data = ((result >> 24) & 0xFFFFFFFF);
        switch (op) {

	case DMI_OP_READ: {
	    fprintf (logfile_fp, "C_to_S  READ  0x%04x\n", addr);
	    break;
	}
	case DMI_OP_WRITE: {
	    fprintf (logfile_fp, "C_to_S  WRITE  0x%04x  0x%08x\n", addr, data);
	    break;
	}
	case DMI_OP_SHUTDOWN: {
	    fprintf (logfile_fp, "C_to_S  SHUTDOWN\n");
	    break;
	}
	case DMI_OP_START_COMMAND: {
	    fprintf (logfile_fp, "C_to_S  ======== START_COMMAND %0d\n", command_num);
	    command_num++;
	    break;
	}
	default: {
	    fprintf (logfile_fp, "C_to_S ERROR: Unrecognized op %0d; ignored\n", op);

	    fprintf (stderr,
		     "ERROR: c_debug_client_request_recv: Unrecognized op %0d; ignored\n",
		     op);
	}
	}
	fflush (logfile_fp);
    }

    return  result;
}

// ================================================================
// Send 4-byte response 'data' to debug client.
// Returns fail/ok status

uint8_t c_debug_client_response_send (const uint32_t data)
{
    int      fd = connected_sockfd;
    int      data_size = 4;    // 4 bytes
    int      n_sent    = 0;
    int      n_iters   = 0;
    uint8_t *p_data    = (uint8_t *) & data;

    while (n_sent < data_size) {
	int n = write (fd, p_data + n_sent, (data_size - n_sent));
	if ((n < 0) && (errno != EAGAIN) && (errno != EWOULDBLOCK)) {
	    if (logfile_fp != NULL) {
		fprintf (logfile_fp, "ERROR: c_debug_client_response_send (0x%08x) failed\n", data);
		fprintf (logfile_fp, "    Sent %0d bytes so far (of %0d)\n", n_sent, data_size);
		fprintf (logfile_fp, "    write (sock, ...) => %0d\n", n);
	    }
	    return DMI_STATUS_ERR;
	}
	else if (n > 0) {
	    n_sent += n;
	}

	n_iters++;
	if ((n_iters > 0) && ((n_iters % 0x1000000) == 0)) {
	    if (logfile_fp != NULL) {
		fprintf (logfile_fp, "WARNING: c_debug_client_response_send (0x%08x) stalled?\n", data);
		fprintf (logfile_fp, "    Sent %0d bytes so far (of %0d)\n", n_sent, data_size);
		fprintf (logfile_fp, "    %0d iterations so far\n", n_iters);
	    }
	}
    }
    fsync (fd);

    if (logfile_fp != NULL) {
	fprintf (logfile_fp, "S_to_C  0x%08x\n", data);
	fflush (logfile_fp);
    }

    return DMI_STATUS_OK;
}

// ================================================================
// This 'main' procedure is for standalone testing of this C server code.
// It listens on the server socket for a connection from Dsharp.
// It simply prints out read/write commands from Dsharp,
// and responds to read commands with an incrementing integer.

#ifdef TEST_COMMS

int main (int argc, char *argv [])
{
    uint8_t   status;

    uint64_t  req;
    uint8_t  *p_req = (uint8_t *) (& req);
    uint8_t   req_op;
    uint16_t  req_addr;
    uint32_t  req_data;

    uint32_t  rsp_data = 0;

    status = c_debug_client_connect (port);
    if (status != DMI_STATUS_OK) {
	return 1;
    }

    while (true) {
	req    = c_debug_client_request_recv (0);

	status     = p_req [7];

	req_op     = p_req [0];

	req_addr   = p_req [2];
	req_addr   = ((req_addr << 8) | p_req [1]);

	req_data   = p_req [6];
	req_data   = ((req_data << 8) | p_req [5]);
	req_data   = ((req_data << 8) | p_req [4]);
	req_data   = ((req_data << 8) | p_req [3]);

	if (status == DMI_STATUS_UNAVAIL) {
	    usleep (1000);
	    continue;
	}

	if (status == DMI_STATUS_ERR)
	    break;

	if (logfile_fp != NULL)
	    fprintf (logfile_fp, "================\n");
	if (req_op == DMI_OP_SHUTDOWN) {
	    if (logfile_fp != NULL)
		fprintf (logfile_fp, "SHUTDOWN\n");
	    break;
	}
	else if (req_op == DMI_OP_READ) {
	    if (logfile_fp != NULL) {
		fprintf (logfile_fp, "READ  addr '%04x'\n", req_addr);
		fprintf (logfile_fp, "      => sending response 0x%08x\n", rsp_data);
	    }
	    status = c_debug_client_response_send (rsp_data);
	    if (status == DMI_STATUS_ERR)
		break;
	    rsp_data++;
	}
	else if (req_op == DMI_OP_WRITE) {
	    if (logfile_fp != NULL)
		fprintf (logfile_fp, "WRITE  addr '%04x'  data '%08x'\n", req_addr, req_data);
	}
	else {
	    if (logfile_fp != NULL)
		fprintf (stderr, "ERROR: unknown command: %0d\n", req_op);
	    continue;
	}
    }
    return 0;
}

#endif

// ****************************************************************
// ****************************************************************
// ****************************************************************