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

    textbuf.c

    Debugger text buffering engine.

    Copyright Nicola Salmoria and the MAME Team.
    Visit http://mamedev.org for licensing and usage restrictions.

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

#include "mamecore.h"
#include "textbuf.h"



/***************************************************************************
    CONSTANTS
***************************************************************************/

#define MAX_LINE_LENGTH			250



/***************************************************************************
    TYPE DEFINITIONS
***************************************************************************/

/* typedef struct _text_buffer text_buffer; -- declared in textbuf.h */
struct _text_buffer
{
	char *					buffer;
	INT32 *					lineoffs;
	INT32					bufsize;
	INT32					bufstart;
	INT32					bufend;
	INT32					linesize;
	INT32					linestart;
	INT32					lineend;
	UINT32					linestartseq;
	INT32					maxwidth;
};



/***************************************************************************
    INLINE FUNCTIONS
***************************************************************************/

/*-------------------------------------------------
    buffer_used - return the number of bytes
    currently held in the buffer
-------------------------------------------------*/

INLINE INT32 buffer_used(text_buffer *text)
{
	INT32 used = text->bufend - text->bufstart;
	if (used < 0)
		used += text->bufsize;
	return used;
}


/*-------------------------------------------------
    buffer_space - return the number of bytes
    available in the buffer
-------------------------------------------------*/

INLINE INT32 buffer_space(text_buffer *text)
{
	return text->bufsize - buffer_used(text);
}



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

    Buffer object management

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

/*-------------------------------------------------
    text_buffer_alloc - allocate a new text buffer
-------------------------------------------------*/

text_buffer *text_buffer_alloc(UINT32 bytes, UINT32 lines)
{
	text_buffer *text;

	/* allocate memory for the text buffer object */
	text = malloc(sizeof(*text));
	if (!text)
		return NULL;

	/* allocate memory for the buffer itself */
	text->buffer = malloc(bytes);
	if (!text->buffer)
	{
		free(text);
		return NULL;
	}

	/* allocate memory for the lines array */
	text->lineoffs = malloc(lines * sizeof(text->lineoffs[0]));
	if (!text->lineoffs)
	{
		free(text->buffer);
		free(text);
		return NULL;
	}

	/* initialize the buffer description */
	text->bufsize = bytes;
	text->linesize = lines;
	text_buffer_clear(text);

	return text;
}


/*-------------------------------------------------
    text_buffer_free - free a previously allocated
    text buffer
-------------------------------------------------*/

void text_buffer_free(text_buffer *text)
{
	if (text->lineoffs)
		free(text->lineoffs);
	if (text->buffer)
		free(text->buffer);
	free(text);
}


/*-------------------------------------------------
    text_buffer_clear - clear a text buffer
-------------------------------------------------*/

void text_buffer_clear(text_buffer *text)
{
	/* reset all the buffer pointers and other bits */
	text->bufstart = 0;
	text->bufend = 0;

	text->linestart = 0;
	text->lineend = 0;
	text->linestartseq = 0;

	text->maxwidth = 0;

	/* create the initial line */
	text->lineoffs[0] = 0;
	text->buffer[text->lineoffs[0]] = 0;
}



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

    Adding data to the buffer

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

/*-------------------------------------------------
    text_buffer_print - print data to the text
    buffer
-------------------------------------------------*/

void text_buffer_print(text_buffer *text, const char *data)
{
	text_buffer_print_wrap(text, data, 10000);
}


/*-------------------------------------------------
    text_buffer_print_wrap - print data to the
    text buffer with word wrapping to a given
    column
-------------------------------------------------*/

void text_buffer_print_wrap(text_buffer *text, const char *data, int wrapcol)
{
	INT32 stopcol = (wrapcol < MAX_LINE_LENGTH) ? wrapcol : MAX_LINE_LENGTH;
	INT32 needed_space;

	/* we need to ensure there is enough space for this string plus enough for the max line length */
	needed_space = (INT32)strlen(data) + MAX_LINE_LENGTH;

	/* make space in the buffer if we need to */
	while (buffer_space(text) < needed_space && text->linestart != text->lineend)
	{
		text->linestartseq++;
		if (++text->linestart >= text->linesize)
			text->linestart = 0;
		text->bufstart = text->lineoffs[text->linestart];
	}

	/* now add the data */
	for ( ; *data; data++)
	{
		int ch = *data;
		int linelen;

		/* a CR resets our position */
		if (ch == '\r')
			text->bufend = text->lineoffs[text->lineend];

		/* non-CR data is just characters */
		else if (ch != '\n')
			text->buffer[text->bufend++] = ch;

		/* an explicit newline or line-too-long condition inserts a newline */
		linelen = text->bufend - text->lineoffs[text->lineend];
		if (ch == '\n' || linelen >= stopcol)
		{
			int overflow = 0;

			/* if we're wrapping, back off until we hit a space */
			if (linelen >= wrapcol)
			{
				/* scan backwards, removing characters along the way */
				overflow = 1;
				while (overflow < linelen && text->buffer[text->bufend - overflow] != ' ')
					overflow++;

				/* if we found a space, take it; otherwise, reset and pretend we didn't try */
				if (overflow < linelen)
					linelen -= overflow;
				else
					overflow = 0;
			}

			/* did we beat the max width */
			if (linelen > text->maxwidth)
				text->maxwidth = linelen;

			/* append a terminator */
			if (overflow == 0)
				text->buffer[text->bufend++] = 0;
			else
				text->buffer[text->bufend - overflow] = 0;

			/* determine what the next line will be */
			if (++text->lineend >= text->linesize)
				text->lineend = 0;

			/* if we're out of lines, consume the next one */
			if (text->lineend == text->linestart)
			{
				text->linestartseq++;
				if (++text->linestart >= text->linesize)
					text->linestart = 0;
				text->bufstart = text->lineoffs[text->linestart];
			}

			/* if we don't have enough room in the buffer for a max line, wrap to the start */
			if (text->bufend + MAX_LINE_LENGTH + 1 >= text->bufsize)
				text->bufend = 0;

			/* create a new empty line */
			text->lineoffs[text->lineend] = text->bufend - (overflow ? (overflow - 1) : 0);
		}
	}

	/* NULL terminate what we have on this line */
	text->buffer[text->bufend] = 0;
}



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

    Reading data from the buffer

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

/*-------------------------------------------------
    text_buffer_max_width - return the maximum
    width of all lines seen so far
-------------------------------------------------*/

UINT32 text_buffer_max_width(text_buffer *text)
{
	return text->maxwidth;
}


/*-------------------------------------------------
    text_buffer_num_lines - return the number of
    lines in the text buffer
-------------------------------------------------*/

UINT32 text_buffer_num_lines(text_buffer *text)
{
	INT32 lines = text->lineend + 1 - text->linestart;
	if (lines <= 0)
		lines += text->linesize;
	return lines;
}


/*-------------------------------------------------
    text_buffer_line_index_to_seqnum - convert a
    line index into a sequence number
-------------------------------------------------*/

UINT32 text_buffer_line_index_to_seqnum(text_buffer *text, UINT32 index)
{
	return text->linestartseq + index;
}


/*-------------------------------------------------
    text_buffer_get_seqnum_line - get a pointer to
    an indexed line in the buffer
-------------------------------------------------*/

const char *text_buffer_get_seqnum_line(text_buffer *text, UINT32 seqnum)
{
	UINT32 numlines = text_buffer_num_lines(text);
	UINT32 index = seqnum - text->linestartseq;
	if (index >= numlines)
		return NULL;
	return &text->buffer[text->lineoffs[(text->linestart + index) % text->linesize]];
}
