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add Berkeley specific copyright notice
[unix-history] / usr / src / sys / tahoe / align / Aoperand.c
/*-
* Copyright (c) 1986 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Computer Consoles Inc.
*
* %sccs.include.redist.c%
*
* @(#)Aoperand.c 7.1 (Berkeley) %G%
*/
#include "align.h"
#define illegal(x) ((look_at->add_modes & x)==0)
#define legal(x) !illegal(x)
struct oprnd *operand(infop, number)
register process_info *infop;
int number;
/*
* Enter with pc pointing to an operand descriptor
* in the 'text'. Decode the addressing mode, get
* the effective address and some data from there.
* Leave pc on the next oerand specifier or opcode.
* Returns a pointer to a 'decoded operand' structure,
* actually one of the 4 pre-allocated .
*
* This routine should be called in such a sequence
* that pc will not have to be backed up to get some
* operand. For example, operand(0) and then operand(1)
* and then operand(2) is OK. Even operand(0), operand(1),
* operand(1) is OK. The rule is that operand(N) should not
* be called before operand(N-1) was.
*
***********************************************************/
{
register struct oprnd *next;
register struct operand_des *look_at;
register int header,reg_num,shift_count, displ;
register int keep_last;
next = &decoded[number];
if (number <= last_operand) return(next);
if (number == last_operand+1) last_operand = number;
else
{
printf ("Wrong sequence of OPERAND calls (alignment code)\n");
return (&decoded[number]);
};
look_at = &Table[opCODE].operand[number];
next->data2 = 0; /* Prepare for quad fetch */
next->length = look_at->length;
if (look_at->add_modes == Brd)
{
next->mode = Add;
switch(look_at->length)
{
case 1:
displ = get_byte(infop, pc);
pc++;
break;
case 2:
displ = get_word(infop, pc);
pc +=2;
break;
default:
printf ("Wrong branch displacement(alignment code)\n");
};
next->address = pc+displ;
return(next);
};
/* Not branch displacement, real operand */
header = get_byte(infop, pc) & 0xff;
pc++;
reg_num = header & 0xf;
switch (header >> 4 & 0xf) {
case 0: /* Short literals */
case 1:
case 2:
case 3:
if (illegal(Lit)) exception(infop, ILL_ADDRMOD);
next->mode = Imm;
next->data = header;
break;
case 4: /* Indexed register */
if (illegal(Add) || reg_num==PCOUNTER || reg_num==SPOINTER)
exception (infop, ILL_ADDRMOD);
keep_last = last_operand;
last_operand = number - 1; /* To get real results */
next = operand(infop, number); /* Get base address (recursive) */
last_operand = keep_last;
if
(! (next->mode & Indx)) exception (infop, ILL_ADDRMOD);
switch (look_at->length)
{
case 1:
shift_count = 0;
break;
case 2:
shift_count = 1;
break;
case 4:
shift_count = 2;
break;
case 8:
shift_count = 3;
break;
default:
printf("Wrong data length in table(alignment code)\n");
};
next->address += (Register(infop,reg_num) << shift_count);
next->mode |= (look_at->add_modes & M); /* Set R/W bits */
trytoread (infop,next,number);
break;
case 5: /* Direct register */
if (illegal (Dir) || reg_num==PCOUNTER ||
reg_num==SPOINTER && legal(R)) exception (infop, ILL_ADDRMOD);
next->mode = Dir;
next->data = Register(infop,reg_num);
next->mode |= (look_at->add_modes & M); /* Set R/W bits */
next->reg_number = reg_num;
if (look_at->length == 8)
{
if (reg_num >= SPOINTER-1 || (reg_num & 1)==1 )
exception (infop, ILL_ADDRMOD);
else next->data2 = Register(infop,reg_num+1);
};
break;
case 6: /* Indirect register */
if (illegal(Add) || reg_num==PCOUNTER )
exception (infop, ILL_ADDRMOD);
next->mode = Add;
next->mode |= (look_at->add_modes & M); /* Set R/W bits */
if (reg_num != SPOINTER) next->mode |= Indx; /* (sp) not indexable*/
next->reg_number = reg_num;
next->address = Register(infop,reg_num);
trytoread (infop,next,number);
break;
case 7: /* Autodecrement SP */
if (illegal(Add) || reg_num!=SPOINTER || look_at->length != 4 ||
legal(R)) exception (infop, ILL_ADDRMOD);
next->mode = SPmode; /* Implies Add */
next->mode |= W; /* Set R/W bits */
next->reg_number = SPOINTER;
next->length = 4; /* Regardless of big table */
sp -= 4;
next->address = sp;
break;
case 8: /* Immediate or (sp)+ */
switch (reg_num) {
case 8: /* Immediate byte */
if (illegal(Imm)) exception (infop, ILL_ADDRMOD);
next->mode = Imm;
next->data = get_byte(infop, pc);
pc++;
break;
case 9: /* Immediate word */
if (illegal(Imm)) exception (infop, ILL_ADDRMOD);
next->mode = Imm;
next->data = get_word(infop, pc);
pc +=2;
break;
case 0xf : /* Immediate longword */
if (illegal(Imm)) exception (infop, ILL_ADDRMOD);
next->mode = Imm;
next->data = get_longword(infop, pc);
pc +=4;
break;
case 0xe: /* Autoincrement sp */
if (illegal(Add) || legal(W) ||
look_at->length != 4) exception (infop, ILL_ADDRMOD);
next->mode = SPmode; /* Implies Add */
next->reg_number = SPOINTER;
next->address = sp;
next->data = get_longword(infop, sp);
next->length = 4; /* Regardless of big table */
sp += 4;
break;
default:
exception (infop, ILL_ADDRMOD);
};
if (look_at -> length == 8) /* Quadword fetch,not (sp)+ */
{
next->data2 = next->data;
if (next->data2 >= 0) next->data = 0;
else next->data = -1;
}
break;
case 9: /* Autoincrement deferred SP or PC */
if (reg_num !=PCOUNTER && reg_num !=SPOINTER )
exception (infop, ILL_ADDRMOD);
if (reg_num == PCOUNTER && illegal(Abs) ||
reg_num == SPOINTER && illegal(Add))
exception (infop, ILL_ADDRMOD);
next->mode = Add | (look_at->add_modes & M) | Indx;
next->address = get_longword (infop, (reg_num == PCOUNTER)?pc : sp );
Replace (infop,reg_num, Register(infop,reg_num)+4);
trytoread (infop,next,number);
break;
case 0xa: /* Register or PC + byte displacement */
if (reg_num != PCOUNTER && illegal(Add) ||
reg_num == PCOUNTER && illegal(Pcrel) ) exception (infop, ILL_ADDRMOD);
next->mode = Add | (look_at->add_modes & M);
if (reg_num != SPOINTER &&
look_at->add_modes != PR) next->mode |= Indx;
displ = get_byte(infop,pc);
pc++;
next->address = Register(infop,reg_num)+displ;
trytoread (infop,next,number);
break;
case 0xb: /* Same, indirect */
if (illegal(Add)) exception (infop, ILL_ADDRMOD);
next->mode = Add | (look_at->add_modes & M) | Indx;
displ = get_byte(infop,pc);
pc++;
next->address = get_longword(infop, Register(infop,reg_num)+displ);
trytoread (infop,next,number);
break;
case 0xc: /* Register or PC + word displacement */
if (reg_num != PCOUNTER && illegal(Add) ||
reg_num == PCOUNTER && illegal(Pcrel) ) exception (infop, ILL_ADDRMOD);
next->mode = Add | (look_at->add_modes & M);
if (reg_num != SPOINTER &&
look_at->add_modes != PR) next->mode |= Indx;
displ = get_word(infop,pc);
pc +=2;
next->address = Register(infop,reg_num)+displ;
trytoread (infop,next,number);
break;
case 0xd: /* Same, indirect */
if (illegal(Add)) exception (infop, ILL_ADDRMOD);
next->mode =Add | (look_at->add_modes & M) | Indx ;
displ = get_word(infop,pc);
pc +=2;
next->address = get_longword (infop,Register(infop,reg_num)+displ);
trytoread (infop,next,number);
break;
case 0xe: /* Register or PC + longword displacement */
if (reg_num != PCOUNTER && illegal(Add) ||
reg_num == PCOUNTER && illegal(Pcrel) ) exception (infop, ILL_ADDRMOD);
next->mode = Add | (look_at->add_modes & M);
if (reg_num != SPOINTER &&
look_at->add_modes != PR) next->mode |= Indx;
displ = get_longword(infop,pc);
pc += 4;
next->address = Register(infop,reg_num)+displ;
trytoread (infop,next,number);
break;
case 0xf: /* Same, indirect */
if (illegal(Add)) exception (infop, ILL_ADDRMOD);
next->mode = Add | (look_at->add_modes & M) | Indx;
displ = get_longword(infop,pc);
pc +=4;
next->address = get_longword(infop, Register(infop,reg_num)+displ);
trytoread (infop,next,number);
};
return(next);
}
trytoread (infop,pointer,number)
process_info *infop;
struct oprnd *pointer;
int number;
/*
/* Receives the opcode operand number and a pointer
/* to the 'decoded' operand structure.
/* If it's defined as readable data in the big table,
/* it returns the data, sign extended.
/*
/**********************************************************/
{
register struct operand_des *look_at;
look_at = &Table[opCODE].operand[number];
if (legal(R))
switch (look_at->length)
{
case 1:
pointer->data = get_byte (infop,pointer->address);
break;
case 2:
pointer->data = get_word (infop,pointer->address);
break;
case 4:
pointer->data = get_longword (infop,pointer->address);
break;
case 8:
pointer->data = get_longword (infop,pointer->address);
pointer->data2 = get_longword (infop,pointer->address+4);
break;
default:
printf ("Wrong data length in table (alignment code)\n");
};
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.