/*
 * output.c
 *
 * code for actually outputting the assembled code
 */

//#include <ctype.h>
#include <errno.h>
#include <stdio.h>
//#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define __output_c_seen__
//#include "instab.h"
#include "lwasm.h"

void write_code_raw(asmstate_t *as, FILE *of);
void write_code_decb(asmstate_t *as, FILE *of);
void write_code_rawrel(asmstate_t *as, FILE *of);

void write_code(asmstate_t *as)
{
	FILE *of;
	
	if (as -> errorcount > 0)
	{
		fprintf(stderr, "Not doing output due to assembly errors.\n");
		return;
	}
	
	of = fopen(as -> outfile, "wb");
	if (!of)
	{
		fprintf(stderr, "Cannot open '%s' for output", as -> outfile);
		perror("");
		return;
	}

	switch (as -> outformat)
	{
	case OUTPUT_RAW:
		write_code_raw(as, of);
		break;
		
	case OUTPUT_DECB:
		write_code_decb(as, of);
		break;
		
	case OUTPUT_RAWREL:
		write_code_rawrel(as, of);
		break;
		
	default:
		fprintf(stderr, "BUG: unrecognized output format when generating output file\n");
		fclose(of);
		unlink(as -> outfile);
		return;
	}

	fclose(of);
}

/*
rawrel output treats an ORG directive as an offset from the start of the
file. Undefined results will occur if an ORG directive moves the output
pointer backward. This particular implementation uses "fseek" to handle
ORG requests and to skip over RMBs.

This simple brain damanged method simply does an fseek before outputting
each instruction.
*/
void write_code_rawrel(asmstate_t *as, FILE *of)
{
	sourceline_t *cl;
	
	for (cl = as -> source_head; cl; cl = cl -> next)
	{
		if (cl -> nocode)
			continue;
		
		fseek(of, cl -> addr, SEEK_SET);
		fwrite(cl -> codebytes, cl -> numcodebytes, 1, of);
	}
}

/*
raw merely writes all the bytes directly to the file as is. ORG is just a
reference for the assembler to handle absolute references. Multiple ORG
statements will produce mostly useless results
*/
void write_code_raw(asmstate_t *as, FILE *of)
{
	sourceline_t *cl;
	
	for (cl = as -> source_head; cl; cl = cl -> next)
	{
		if (cl -> nocode && cl -> len > 0)
		{
			int i;
			for (i = 0; i < cl -> len; i++)
				fwrite("\0", 1, 1, of);
			continue;
		}
		if (cl -> nocode)
			continue;
		
		fwrite(cl -> codebytes, cl -> numcodebytes, 1, of);
	}
}

void write_code_decb(asmstate_t *as, FILE *of)
{
	long preambloc;
	sourceline_t *cl;
	int blocklen = -1;
	int nextcalc = -1;
	unsigned char outbuf[5];
	
	for (cl = as -> source_head; cl; cl = cl -> next)
	{
		if (cl -> nocode)
			continue;
		if (cl -> addr != nextcalc && cl -> numcodebytes > 0)
		{
			// need preamble here
			if (blocklen > 0)
			{
				fseek(of, preambloc, SEEK_SET);
				outbuf[0] = (blocklen >> 8) & 0xFF;
				outbuf[1] = blocklen & 0xFF;
				fwrite(outbuf, 2, 1, of);
				fseek(of, 0, SEEK_END);
			}
			blocklen = 0;
			nextcalc = cl -> addr;
			outbuf[0] = 0x00;
			outbuf[1] = 0x00;
			outbuf[2] = 0x00;
			outbuf[3] = (nextcalc >> 8) & 0xFF;
			outbuf[4] = nextcalc & 0xFF;
			preambloc = ftell(of) + 1;
			fwrite(outbuf, 5, 1, of);
		}
		nextcalc += cl -> numcodebytes;
		fwrite(cl -> codebytes, cl -> numcodebytes, 1, of);
		blocklen += cl -> numcodebytes;
	}
	if (blocklen > 0)
	{
		fseek(of, preambloc, SEEK_SET);
		outbuf[0] = (blocklen >> 8) & 0xFF;
		outbuf[1] = blocklen & 0xFF;
		fwrite(outbuf, 2, 1, of);
		fseek(of, 0, SEEK_END);
	}
	
	// now write postamble
	outbuf[0] = 0xFF;
	outbuf[1] = 0x00;
	outbuf[2] = 0x00;
	outbuf[3] = (as -> execaddr >> 8) & 0xFF;
	outbuf[4] = (as -> execaddr) & 0xFF;
	fwrite(outbuf, 5, 1, of);
}