/*
 * picasm -- pic12bit.c
 *
 * Copyright 1995-2004 Timo Rossi, <trossi@iki.fi>
 * See the file LICENSE for license terms.
 * 
 */

#include <stdio.h>

#include "picasm.h"
#include "token.h"
#include "symtab.h"

/*
 * Assemble 12-bit PIC code
 *
 */
int
assemble_12bit_mnemonic(int op)
{
    long val;
    struct symbol *sym;
    char *cp;
    int symtype;
    long t;

    switch(op)
    {
    case KW_ANDLW:
    case KW_IORLW:
    case KW_XORLW:
	if(get_expression(&val) != OK)
	    return FAIL;

	if(val < -0x80 || val > 0xff)
	    error(1, "8-bit literal out of range");

	if(val < 0)
	    val += 0x100;

	switch(op)
	{
        case KW_ANDLW: gen_code(0xe00 | val); break;
	case KW_IORLW: gen_code(0xd00 | val); break;
	case KW_XORLW: gen_code(0xf00 | val); break;
	}
	break;

    case KW_MOVLW:
	if(gen_byte_c(0xc00) != OK)
	    return FAIL;
	break;

    case KW_ADDWF:
    case KW_SUBWF:
    case KW_ANDWF:
    case KW_IORWF:
    case KW_XORWF:
    case KW_COMF:
    case KW_DECF:
    case KW_INCF:
    case KW_MOVF:
    case KW_DECFSZ:
    case KW_INCFSZ:
    case KW_RLF:
    case KW_RRF:
    case KW_SWAPF:
	if(get_expression(&val) != OK)
	    return FAIL;

	if(val < 0 || val > 0x1f)
	    error(0, "Register file address out of range");

	t = 1;
	if(token_type == TOK_COMMA)
	{
	    get_token();
	    if(get_expression(&t) != OK)
		return FAIL;

	    if(warnlevel > 0 && t != 0 && t != 1)
		warning("Destination specifier not 0 or 1");
	}
	else
	{
	    if(warnlevel > 0)
		warning("Destination speficier omitted");
	}
	val = (val & 0x1f) | (t != 0 ? 0x20 : 0);
	switch(op)
	{
        case KW_ADDWF:  gen_code(0x1c0 | val); break;
	case KW_SUBWF:  gen_code(0x080 | val); break;
	case KW_ANDWF:  gen_code(0x140 | val); break;
	case KW_IORWF:  gen_code(0x100 | val); break;
	case KW_XORWF:  gen_code(0x180 | val); break;
	case KW_COMF:   gen_code(0x240 | val); break;
	case KW_DECF:   gen_code(0x0c0 | val); break;
	case KW_INCF:   gen_code(0x280 | val); break;
	case KW_MOVF:   gen_code(0x200 | val); break;
	case KW_DECFSZ: gen_code(0x2c0 | val); break;
	case KW_INCFSZ: gen_code(0x3c0 | val); break;
	case KW_RLF:    gen_code(0x340 | val); break;
	case KW_RRF:    gen_code(0x300 | val); break;
	case KW_SWAPF:  gen_code(0x380 | val); break;
	}
	break;

    case KW_CLRF:
    case KW_MOVWF:
	if(get_expression(&val) != OK)
	    return FAIL;

	if(val < 0 || val > 0x1f)
	    error(0, "Register file address out of range");
	switch(op)
	{
        case KW_CLRF:  gen_code(0x060 | val); break;
	case KW_MOVWF: gen_code(0x020 | val); break;
	}
	break;

    case KW_BCF:
    case KW_BSF:
    case KW_BTFSC:
    case KW_BTFSS:
	if(get_expression(&val) != OK)
	    return FAIL;

	if(val < 0 || val > 0x1f)
	    error(0, "Register file address out of range");

	if(token_type != TOK_COMMA)
	{
	    error(1, "',' expected");
	    return FAIL;
	}
	get_token();
	if(get_expression(&t) != OK)
	    return FAIL;

	if(t < 0 || t > 7)
	{
	    error(0, "Bit number out of range");
	}
	val |= (t << 5);
	switch(op)
	{
        case KW_BCF:   gen_code(0x400 | val); break;
	case KW_BSF:   gen_code(0x500 | val); break;
	case KW_BTFSC: gen_code(0x600 | val); break;
	case KW_BTFSS: gen_code(0x700 | val); break;
	}
	break;

    case KW_CALL:
    case KW_GOTO:
	t = 0;
	if(token_type == TOK_IDENTIFIER || token_type == TOK_LOCAL_ID)
	{
	    symtype =
		(token_type == TOK_IDENTIFIER ? SYMTAB_GLOBAL : SYMTAB_LOCAL);

	    if(symtype == SYMTAB_LOCAL && local_level == 0)
	    {
		error(1, "Local symbol outside a LOCAL block");
		return FAIL;
	    }

	    sym = lookup_symbol(token_string, symtype);
	    if(sym == NULL || sym->type == SYM_FORWARD)
	    {
		if(sym == NULL)
		{
		    sym = add_symbol(token_string, symtype);
		    sym->type = SYM_FORWARD;
		}

		val = 0;
		add_patch(symtype, sym,
			  (op == KW_CALL ? PATCH8 : PATCH9));
		t = 1;
		get_token();
		goto gen_goto_call;
	    }
	}

	if(get_expression(&val) != OK)
	    return FAIL;

	if(val < 0 || val >= prog_mem_size)
	    error(0, "GOTO/CALL address out of range");

	if(op == KW_CALL && (val & 0x100) != 0)
	    error(0, "CALL address in upper half of a page");

gen_goto_call:
	switch(op)
	{
        case KW_CALL: gen_code(0x900 | (val & 0xff)); break;
	case KW_GOTO: gen_code(0xa00 | (val & 0x1ff)); break;
	}
	if(t)
	    list_flags |= LIST_FORWARD;
	break;

    case KW_TRIS:
	if(get_expression(&t) != OK)
	    return FAIL;

	if(t != 5 && t != 6 && t != 7)
	    error(0, "Invalid register address for TRIS");

	gen_code(0x000 | t);
	break;

/*
 * RETLW allows multiple parameters/strings, for generating lookup tables
 *
 * DT is a Microchip-compatible directive that generates retlw instructions
 * it is handled exactly the same as the actual retlw mnemonic here
 */
    case KW_DT:
    case KW_RETLW:
	for(;;)
	{
	    if(token_type == TOK_STRCONST)
	    {
		for(cp = token_string; *cp != '\0'; cp++)
		    gen_code(0x800 | (int)((unsigned char)(*cp)));
		get_token();
	    }
	    else
	    {
		if(gen_byte_c(0x800) != OK)
		    return FAIL;
	    }

	    if(token_type != TOK_COMMA)
		break;

	    get_token();
	}
	break;

    case KW_NOP:
	gen_code(0x000);
	break;

    case KW_CLRW:
	gen_code(0x040);
	break;

    case KW_OPTION:
	gen_code(0x002);
	break;

    case KW_SLEEP:
	gen_code(0x003);
	break;

    case KW_CLRWDT:
	gen_code(0x004);
	break;

    case KW_RETURN:
    case KW_RETFIE:
    case KW_ADDLW:
    case KW_SUBLW:
	error(1, "Unimplemented instruction for PIC%s", pic_name);
	return FAIL;

    default:
	error(1, "Syntax error");
	return FAIL;
    }

    return OK;
}