/* i51mch.c */

/*
 *  Copyright (C) 1998-2026  Alan R. Baldwin
 *
 *  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/>.
 *
 *
 * Alan R. Baldwin
 * 721 Berkeley St.
 * Kent, Ohio  44240
 *
 *   This Assember Ported by
 *	John L. Hartman	(JLH)
 *	jhartman at compuserve dot com
 *	noice at noicedebugger dot com
 *
 *  Benny Kim (2011/07/21)
 *  bennykim at coreriver dot com
 *  Fixed bugs in relative address with "."
 */

#include "asxxxx.h"
#include "i8051.h"

char	*cpu	= "Intel 8051";
char	*dsft	= "asm";

/*
 * Opcode Cycle Definitions
 */
#define	OPCY_SDP	((char) (0xFF))
#define	OPCY_ERR	((char) (0xFE))

#define	OPCY_NONE	((char) (0x80))
#define	OPCY_MASK	((char) (0x7F))

#define	UN	((char) (OPCY_NONE | 0x00))

/*
 * 8051 Cycle Count
 *
 *	opcycles = i51pg1[opcode]
 */
static char i51pg1[256] = {
/*--*--* 0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F */
/*--*--* -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  - */
/*00*/  12,24,24,12,12,12,12,12,12,12,12,12,12,12,12,12,
/*10*/  24,24,24,12,12,12,12,12,12,12,12,12,12,12,12,12,
/*20*/  24,24,24,12,12,12,12,12,12,12,12,12,12,12,12,12,
/*30*/  24,24,24,12,12,12,12,12,12,12,12,12,12,12,12,12,
/*40*/  24,24,12,24,12,12,12,12,12,12,12,12,12,12,12,12,
/*50*/  24,24,12,24,12,12,12,12,12,12,12,12,12,12,12,12,
/*60*/  24,24,12,24,12,12,12,12,12,12,12,12,12,12,12,12,
/*70*/  24,24,24,24,12,24,12,12,12,12,12,12,12,12,12,12,
/*80*/  24,24,24,24,48,24,24,24,24,24,24,24,24,24,24,24,
/*90*/  24,24,24,24,12,12,12,12,12,12,12,12,12,12,12,12,
/*A0*/  24,24,12,24,48,UN,24,24,24,24,24,24,24,24,24,24,
/*B0*/  24,24,12,12,24,24,24,24,24,24,24,24,24,24,24,24,
/*C0*/  24,24,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
/*D0*/  24,24,12,12,12,24,12,12,24,24,24,24,24,24,24,24,
/*E0*/  24,24,24,24,12,12,12,12,12,12,12,12,12,12,12,12,
/*F0*/  24,24,24,24,12,12,12,12,12,12,12,12,12,12,12,12
};

/*
 * Process machine ops.
 */
void
machine(struct mne *mp)
{
	int op, t, t1, v1;
	struct expr e, e1;

	/*
	 * Using Internal Format
	 * For Cycle Counting
	 */
	opcycles = OPCY_NONE;

	clrexpr(&e);
	clrexpr(&e1);

	op = (int) mp->m_valu;
	switch (mp->m_type) {

	case S_INH:
		outab(op);
		break;

	case S_JMP11:
		/*
		 * 11 bit destination.
		 * Top 3 bits become the MSBs of the op-code.
		 */
		expr(&e);
		outrwm(&e, R_PAGX2 | R_J11, op << 8);
		break;

	case S_JMP16:
		expr(&e);
		outab(op);
		outrw(&e, R_NORM);
		break;

	case S_ACC:
		t = addr(&e);
		if (t != S_A)
			xerr('a', "Argument must be A.");
		outab(op);
		break;

	case S_TYP1:
		/* A, direct, @R0, @R1, R0 to R7.  "INC" also allows DPTR */
		t = addr(&e);
		
		switch (t) {
		case S_A:
			outab(op + 4);
			break;

		case S_DIR:
		case S_EXT:
			/* Direct is also legal */
			outab(op + 5);
			outrb(&e, R_PAG0);
			break;

		case S_AT_R:
			outab(op + 6 + e.e_addr);
			break;

		case S_REG:
			outab(op + 8 + e.e_addr);
			break;

		case S_DPTR:
			if (op != 0)
				/* only INC (op=0) has DPTR mode */
				xerr('a', "DPTR allowed only in INC instruction.");
			else
				outab( 0xA3);
			break;

		default:
			xerr('a', "Invalid Addressing Mode.");
		}
		break;

	case S_TYP2:
		/* A,#imm; A,direct; A,@R0; A,@R1; A,R0 to A,R7 */
		t = addr(&e);
		if (t != S_A)
			xerr('a', "First argument must be A.");
		comma(1);
		t1 = addr(&e1);
		
		switch (t1) {
		case S_IMMED:
			outab(op + 4);
			outrb(&e1, R_NORM);
			break;

		case S_DIR:
		case S_EXT:
			outab(op + 5);
			outrb(&e1, R_PAG0);
			break;

		case S_AT_R:
			outab(op + 6 + e1.e_addr);
			break;

		case S_REG:
			outab(op + 8 + (e1.e_addr));
			break;

		default:
			xerr('a', "Invalid Addressing Mode.");
		}
		break;

	case S_TYP3:
		/* dir,A; dir,#imm; 
		 * A,#imm; A,direct; A,@R0; A,@R1; A,R0 to A,R7 
		 * C,direct;  C,/direct
		 */
		t = addr(&e);
		comma(1);
		t1 = addr(&e1);

		switch (t) {
		case S_DIR:
		case S_EXT:
			switch (t1) {
			case S_A:
				outab(op + 2);
				outrb(&e, R_PAG0);
				break;
			
			case S_IMMED:
				outab(op + 3);
				outrb(&e, R_PAG0);
				outrb(&e1, R_NORM);
				break;

			default:
				xerr('a', "Invalid Addressing Mode.");
			}
			break;

		case S_A:
			switch (t1) {
			case S_IMMED:
				outab(op + 4);
				outrb(&e1, R_NORM);
				break;
	
			case S_DIR:
			case S_EXT:
				outab(op + 5);
				outrb(&e1, R_PAG0);
				break;

			case S_AT_R:
				outab(op + 6 + e1.e_addr);
				break;

			case S_REG:
				outab(op + 8 + e1.e_addr);
				break;

			default:
				xerr('a', "Invalid Addressing Mode.");
			}
			break;

		case S_C:
			/* XRL has no boolean version.  Trap it */
			if (op == 0x60)
				xerr('a', "XRL does not support boolean.");

			switch (t1) {
			case S_DIR:
			case S_EXT:
				outab(op + 0x32);
				outrb(&e1, R_PAG0);
				break;
			
			case S_NOT_BIT:
				outab(op + 0x60);
				outrb(&e1, R_PAG0);
				break;
			
			default:
				xerr('a', "Invalid Addressing Mode.");
			}
			break;

		default:
			xerr('a', "Invalid Addressing Mode.");
		}
		break;

	case S_TYP4:
		/* A,direct; A,@R0; A,@R1; A,R0 to A,R7 */
		t = addr(&e);
		if (t != S_A)
			xerr('a', "First argument must be A.");
		comma(1);
		t1 = addr(&e1);

		switch (t1) {
		case S_DIR:
		case S_EXT:
			outab(op + 5);
			outrb(&e1, R_PAG0);
			break;

		case S_AT_R:
			outab(op + 6 + e1.e_addr);
			break;

		case S_REG:
			outab(op + 8 + e1.e_addr);
			break;

		default:
			xerr('a', "Invalid Addressing Mode.");
		}
		break;

	/* MOV instruction, all modes */
	case S_MOV:
		t = addr(&e);
		comma(1);
		t1 = addr(&e1);

		switch (t) {
		case S_A:
			switch (t1) {
			case S_IMMED:
				outab(0x74);
				outrb(&e1, R_NORM);
				break;
	
			case S_DIR:
			case S_EXT:
				outab(0xE5);
				outrb(&e1, R_PAG0);
				break;

			case S_AT_R:
				outab(0xE6 + e1.e_addr);
				break;

			case S_REG:
				outab(0xE8 + e1.e_addr);
				break;

			default:
				xerr('a', "Invalid Addressing Mode.");
			}
			break;

		case S_REG:
			switch (t1) {
			case S_A:
				outab(0xF8 + e.e_addr);
				break;

			case S_IMMED:
				outab(0x78 + e.e_addr);
				outrb(&e1, R_NORM);
				break;
	
			case S_DIR:
			case S_EXT:
				outab(0xA8 + e.e_addr);
				outrb(&e1, R_PAG0);
				break;

			default:
				xerr('a', "Invalid Addressing Mode.");
			}
			break;

		case S_DIR:
		case S_EXT:
			switch (t1) {
			case S_A:
				outab(0xF5);
				outrb(&e, R_PAG0);
				break;

			case S_IMMED:
				outab(0x75);
				outrb(&e, R_PAG0);
				outrb(&e1, R_NORM);
				break;
	
			case S_DIR:
			case S_EXT:
				outab(0x85);
				outrb(&e1, R_PAG0);
				outrb(&e, R_PAG0);
				break;

			case S_AT_R:
				outab(0x86 + e1.e_addr);
				outrb(&e, R_PAG0);
				break;

			case S_REG:
				outab(0x88 + e1.e_addr);
				outrb(&e, R_PAG0);
				break;

			case S_C:
				outab(0x92);
				outrb(&e, R_PAG0);
				break;

			default:
				xerr('a', "Invalid Addressing Mode.");
			}
			break;

		case S_AT_R:
			switch (t1) {
			case S_IMMED:
				outab(0x76 + e.e_addr);
				outrb(&e1, R_NORM);
				break;
	
			case S_DIR:
			case S_EXT:
				outab(0xA6 + e.e_addr);
				outrb(&e1, R_PAG0);
				break;

			case S_A:
				outab(0xF6 + e.e_addr);
				break;

			default:
				xerr('a', "Invalid Addressing Mode.");
			}
			break;

		case S_C:
			if ((t1 != S_DIR) && (t1 != S_EXT))
				xerr('a', "Second argument must be an address.");
			outab(0xA2);
			outrb(&e1, R_PAG0);
			break;

		case S_DPTR:
			if (t1 != S_IMMED)
				xerr('a', "#__ is required second argument.");
			outab(0x90);
			outrw(&e1, R_NORM);
			break;

		default:
			xerr('a', "Invalid Addressing Mode.");
		}
		break;

	case S_BITBR:   /* JB, JBC, JNB bit,rel */
		/* Branch on bit set/clear */
		t = addr(&e);
		if ((t != S_DIR) && (t != S_EXT))
			xerr('a', "Argument must be an address.");

		/* Benny */
		comma(1);
		expr(&e1);

		outab(op);
		outrb(&e, R_PAG0);

		if (mchpcr(&e1, &v1, 1)) {
			if ((v1 < -128) || (v1 > 127))
				xerr('a', "Branching Range Exceeded.");
			outab(v1);
		} else {
			outrb(&e1, R_PCR);
		}
		if (e1.e_mode != S_USER)
			rerr();
		break;

	case S_BR:  /* JC, JNC, JZ, JNZ */
		/* Relative branch */
		/* Benny */
		expr(&e1);
		outab(op);

		if (mchpcr(&e1, &v1, 1)) {
			if ((v1 < -128) || (v1 > 127))
				xerr('a', "Branching Range Exceeded.");
			outab(v1);
		} else {
			outrb(&e1, R_PCR);
		}
		if (e1.e_mode != S_USER)
			rerr();
		break;

	case S_CJNE:
		/* A,#;  A,dir;  @R0,#;  @R1,#;  Rn,# */
		t = addr(&e);
		comma(1);
		t1 = addr(&e1);

		/* Benny */
		comma(1);
		switch (t) {
		case S_A:
			clrexpr(&e);
			expr(&e);
			if (t1 == S_IMMED) {
				outab(op + 4);
				outrb(&e1, R_NORM);
			}
			else if ((t1 == S_DIR) || (t1 == S_EXT)) {
				outab(op + 5);
				outrb(&e1, R_PAG0);
			} else {
				xerr('a', "Invalid Addressing Mode.");
			}
			break;

		case S_AT_R:
			op = (op + 6 + (int) e.e_addr);
			clrexpr(&e);
			expr(&e);
			outab(op);
			if (t1 != S_IMMED)
				xerr('a', "#__ is required second argument.");
			outrb(&e1, R_NORM);
			break;
	
		case S_REG:
			op = (op + 8 + (int) e.e_addr);
			clrexpr(&e);
			expr(&e);
			outab(op);
			if (t1 != S_IMMED)
				xerr('a', "#__ is required second argument.");
			outrb(&e1, R_NORM);
			break;
	
		default:
			xerr('a', "Invalid Addressing Mode.");
			break;
		}

		/* branch destination */
		if (mchpcr(&e, &v1, 1)) {
			if ((v1 < -128) || (v1 > 127))
				xerr('a', "Branching Range Exceeded.");
			outab(v1);
		} else {
			outrb(&e, R_PCR);
		}
		if (e.e_mode != S_USER)
			rerr();
		break;

	case S_DJNZ:
		/* Dir,dest;  Reg,dest */
		t = addr(&e);
		/* Benny */
		comma(1);
		expr(&e1);

		switch (t) {
		case S_DIR:
		case S_EXT:
			outab(op + 5);
			outrb(&e, R_PAG0);
			break;
	
		case S_REG:
			outab(op + 8 + e.e_addr);
			break;

		default:
			xerr('a', "Invalid Addressing Mode.");
		}

		/* branch destination */
		if (mchpcr(&e1, &v1, 1)) {
			if ((v1 < -128) || (v1 > 127))
				xerr('a', "Branching Range Exceeded.");
			outab(v1);
		} else {
			outrb(&e1, R_PCR);
		}
		if (e1.e_mode != S_USER)
			rerr();
		break;

	case S_JMP: 
		/* @A+DPTR */
		t = addr(&e);
		if (t != S_AT_ADP)
			xerr('a', "JMP @A+DPTR is the only allowed mode.");
		outab(op);
		break;

	case S_MOVC:
		/* A,@A+DPTR  A,@A+PC */
		t = addr(&e);
		if (t != S_A)
			xerr('a', "First argument must be A.");
		comma(1);
		t1 = addr(&e1);
		if (t1 == S_AT_ADP) {
			outab(0x93);
		} else
		if (t1 == S_AT_APC) {
			outab(0x83);
		} else {
			xerr('a', "MOVC A,@A+DPTR; A,@A+PC are the allowed modes.");
		}
		break;

	case S_MOVX:
		/* A,@DPTR  A,@R0  A,@R1  @DPTR,A  @R0,A  @R1,A */
		t = addr(&e);
		comma(1);
		t1 = addr(&e1);

		switch (t) {
		case S_A:
			switch (t1) {
			case S_AT_DP:
				outab(0xE0);
				break;

			case S_AT_R:
				outab(0xE2 + e1.e_addr);
				break;

			default:
				xerr('a', "Second argument must be @DPTR or @Rn.");
			}
			break;

		case S_AT_DP:
			if (t1 == S_A) {
				outab(0xF0);
			} else {
				xerr('a', "Second argument must A.");
			}
			break;

		case S_AT_R:
			if (t1 == S_A) {
				outab(0xF2 + e.e_addr);
			} else {
				xerr('a', "Second argument must A.");
			}
			break;

		default:
			xerr('a', "Invalid Addressing Mode.");
		}
		break;

	/* MUL/DIV A,B */
	case S_AB:  
		t = addr(&e);
		if (t != S_RAB)
			xerr('a', "A,B is the only valid argument.");
		outab(op);
		break;

	/* CLR or CPL:  A, C, or bit */
	case S_ACBIT:
		t = addr(&e);
		switch (t) {
		case S_A:
			if (op == 0xB2) {
				outab(0xF4);
			} else {
				outab(0xE4);
			}
			break;

		case S_C:
			outab(op+1);
			break;

		case S_DIR:
		case S_EXT:
			outab(op);
			outrb(&e, R_PAG0);
			break;

		default:
			xerr('a', "Invalid Addressing Mode.");
		}
		break;

	/* SETB C or bit */
	case S_SETB:
		t = addr(&e);
		switch (t) {
		case S_C:
			outab(op+1);
			break;

		case S_DIR:
		case S_EXT:
			outab(op);
			outrb(&e, R_PAG0);
			break;

		default:
			xerr('a', "Invalid Addressing Mode.");
		}
		break;

	/* direct */
	case S_DIRECT: 
		t = addr(&e);
		if (t == S_A) {
			e.e_addr = 0xE0;
			e.e_mode = S_DIR;
		} else
		if (t == S_REG) {
			e.e_mode = S_DIR;
		} else
		if ((t != S_DIR) && (t != S_EXT)) {
			xerr('a', "Argument must be an address.");
			break;
		}
		outab(op);
		outrb(&e, R_PAG0);
		break;

	/* XCHD A,@Rn */
	case S_XCHD:
		t = addr(&e);
		if (t != S_A)
			xerr('a', "First argument must A.");
		comma(1);
		t1 = addr(&e1);
		switch (t1) {
		case S_AT_R:
			outab(op + e1.e_addr);
			break;

		default:
			xerr('a', "Invalid Addressing Mode.");
		}
		break;

	default:
		opcycles = OPCY_ERR;
		xerr('o', "Internal Opcode Error.");
		break;
	}
	if (opcycles == OPCY_NONE) {
		opcycles = i51pg1[cb[0] & 0xFF];
	}
 	/*
	 * Translate To External Format
	 */
	if (opcycles == OPCY_NONE) { opcycles  =  CYCL_NONE; } else
	if (opcycles  & OPCY_NONE) { opcycles |= (CYCL_NONE | 0x3F00); }
}

/*
 * Branch/Jump PCR Mode Check
 */
int
mchpcr(struct expr *esp, int *v, int n)
{
	if (esp->e_base.e_ap == dot.s_area) {
		if (v != NULL) {
#if 1
			/* Allows branching from top-to-bottom and bottom-to-top */
 			*v = (int) (esp->e_addr - dot.s_addr - n);
			/* only bits 'a_mask' are significant, make circular */
			if (*v & s_mask) {
				*v |= (int) ~a_mask;
			}
			else {
				*v &= (int) a_mask;
			}
#else
			/* Disallows branching from top-to-bottom and bottom-to-top */
			*v = (int) ((esp->e_addr & a_mask) - (dot.s_addr & a_mask) - n);
#endif
		}
		return(1);
	}
	if (esp->e_flag==0 && esp->e_base.e_ap==NULL) {
		/*
		 * Absolute Destination
		 *
		 * Use the global symbol '.__.ABS.'
		 * of value zero and force the assembler
		 * to use this absolute constant as the
		 * base value for the relocation.
		 */
		esp->e_flag = 1;
		esp->e_base.e_sp = &sym[1];
	}
	return(0);
}

/*
 * Machine specific initialization
 */

void
minit(void)
{
	struct sym	*sp;
	struct PreDef	*pd;
	int i;
	char pid[8];
	char *p;

	/*
	 * Byte Order
	 */
	hilo = 1;

	/*
	 * First time only:
	 *	add the pre-defined symbols to the table
	 *	as local symbols.
	 */
	if (pass == 0) {
		pd = preDef;
		while (pd->id) {
			strcpy(pid, pd->id);
			for (i=0; i<2; i++) {
				/*
				 * i == 0,  Create Upper Case Symbols
				 * i == 1,  Create Lower Case Symbols
				 */
				if (i == 1) {
					p = pid;
					while (*p) {
						*p = ccase[*p & 0x007F];
						p++;
					}
				}
				sp = lookup(pid);
				if (sp->s_type == S_NEW) {
					sp->s_addr = pd->value;
					sp->s_type = S_USER;
					sp->s_flag = S_LCL | S_ASG;
				}
			}
			pd++;
		}
	}
}
