/*
Status9900.java
(c) 2005-2015 Edward Swartz
All rights reserved. This program and the accompanying materials
are made available under the terms of the Eclipse Public License v1.0
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/epl-v10.html
*/
package v9t9.machine.ti99.cpu;
import ejs.base.utils.HexUtils;
import v9t9.common.cpu.IStatus;
/**
* The CPU status word is a flattened array of bits, many of which are hard to
* calculate. We implement it instead as a class which contains the values
* for which the flags are set. Then, we can save time by not forming the
* word until it's needed.
*
* @author ejs
*/
public class Status9900 implements IStatus {
short lastval; /* last value of calculation */
short lastcmp; /* last compared-to value, usually 0 */
byte lastparity;/* last parity candidate */
short bits; /* other bits: ST_O|ST_X|ST_C|ST_INTLEVEL */
public static final int stset_XOP = 3; // xop bits changed
public static final int stset_CMP = 4; // comparison
public static final int stset_BYTE_CMP = 5; // with bytes
public static final int stset_LAE = 6; // arithmetic...
public static final int stset_LAEO = 7;
public static final int stset_O = 8;
public static final int stset_E = 11;
public static final int stset_BYTE_LAEP = 12;
public static final int stset_SUB_LAECO = 13;
public static final int stset_SUB_BYTE_LAECOP = 14;
public static final int stset_ADD_LAECO = 15;
public static final int stset_ADD_BYTE_LAECOP = 16;
public static final int stset_SHIFT_RIGHT_C = 17;
public static final int stset_SHIFT_LEFT_CO = 18;
public static final int stset_DIV_O = 19;
public static final int stset_LAE_1 = 20;
public static final int stset_BYTE_LAEP_1 = 21;
public static final int stset_ADD_LAECO_REV = 22;
public static final int stset_ADD_LAECO_REV_1 = 23;
public static final int stset_ADD_LAECO_REV_2 = 24;
public static final int stset_ADD_LAECO_REV_N1 = 25;
public static final int stset_ADD_LAECO_REV_N2 = 26;
/* status bits */
public static final short ST_L = (short)0x8000;
public static final short ST_A = (short)0x4000;
public static final short ST_E = (short)0x2000;
public static final short ST_C = (short)0x1000;
public static final short ST_O = (short)0x800;
public static final short ST_P = (short)0x400;
public static final short ST_X = (short)0x200;
public static final short ST_INTLEVEL = (short)0xf;
public Status9900() {
}
Status9900(short lastval, short lastcmp, byte lastparity, short bits) {
this.lastval = lastval;
this.lastcmp = lastcmp;
this.lastparity = lastparity;
this.bits = bits;
}
public Status9900(short val) {
expand(val);
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + bits;
result = prime * result + lastcmp;
result = prime * result + lastparity;
result = prime * result + lastval;
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Status9900 other = (Status9900) obj;
if (bits != other.bits)
return false;
if (lastcmp != other.lastcmp)
return false;
if (lastparity != other.lastparity)
return false;
if (lastval != other.lastval)
return false;
return true;
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#toString()
*/
@Override
public String toString() {
flatten();
return ((bits & Status9900.ST_L) != 0 ? "L" : " ")
+ ((bits & Status9900.ST_A) != 0 ? "A" : " ")
+ ((bits & Status9900.ST_E) != 0 ? "E" : " ")
+ ((bits & Status9900.ST_C) != 0 ? "C" : " ")
+ ((bits & Status9900.ST_O) != 0 ? "O" : " ")
+ ((bits & Status9900.ST_P) != 0 ? "P" : " ")
+ ((bits & Status9900.ST_X) != 0 ? "X" : " ")
+ (HexUtils.toHex2((bits & 0xf)));
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#copyTo(v9t9.engine.cpu.Status9900)
*/
public void copyTo(IStatus copy_) {
Status9900 copy = (Status9900) copy_;
copy.lastval = lastval;
copy.lastcmp = lastcmp;
copy.lastparity = lastparity;
copy.bits = bits;
}
@Override
protected Object clone() {
return new Status9900(lastval, lastcmp, lastparity, bits);
}
/* (non-Javadoc)
* @see v9t9.common.cpu.IStatus#get()
*/
@Override
public short get() {
return bits;
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#flatten()
*/
public short flatten() {
bits = (short) (bits & ~(Status9900.ST_L + Status9900.ST_A + Status9900.ST_E + Status9900.ST_P)
| ((lastval & 0xffff) > (lastcmp & 0xffff) ? Status9900.ST_L : 0)
| (lastval > lastcmp ? Status9900.ST_A : 0)
| (lastval == lastcmp ? Status9900.ST_E : 0)
| (isOddParity(lastparity) ? Status9900.ST_P : 0)
);
return bits;
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#expand(short)
*/
public void expand(short stat) {
lastval = lastcmp = 0;
if ((stat & Status9900.ST_E) == 0) {
if ((stat & Status9900.ST_L + Status9900.ST_A) == 0) {
lastcmp = 2; /* less than arith+logical: 0, 2 */
} else {
lastval++;
if ((stat & Status9900.ST_L) == 0) {
/* less than logical only: 0, 0xfffe (-2) */
lastcmp = (short) -2;
} else if ((stat & Status9900.ST_A) == 0) {
/* less than arithmetic only: 0xfffe (-2), 0 */
lastval = (short) 0xfffe;
}
}
}
lastparity = (byte) ((stat & Status9900.ST_P) != 0 ? 1 : 0);
// preserve reserved bits, e.g. for Forth9900 and its "bank" flag
//bits = (short) ((bits & ~(ST_INTLEVEL + ST_C + ST_O + ST_X)) | (stat & ST_INTLEVEL + ST_C + ST_O + ST_X));
bits = (short) stat;
}
/*
* Set lae, preserve C and O
*/
public void set_LAE(short val) {
lastcmp = 0;
lastval = val;
}
/*
* Set lae, preserve C and O (BYTE)
*/
public void set_BYTE_LAEP(byte val) {
lastval = val;
lastcmp = 0;
lastparity = val;
}
/*
* Set lae, and O if val == 0x8000
*/
public void set_LAEO(short val) {
set_LAE(val);
if (val == (short)0x8000) {
bits |= Status9900.ST_O;
} else {
bits &= ~Status9900.ST_O;
}
}
/*
* For COC, CZC, and TB
*/
public void set_E(boolean equal) {
// TODO: hmm, this actually clears L> and A>, while TB doesn't strictly do that.
if (equal) {
lastval = lastcmp;
} else {
lastcmp = (short) (lastval+1);
}
}
/*
Set laeco for add, preserve none
*/
public void set_ADD_LAECO(short dst,short src) {
short res = (short) (dst + src);
bits &= ~(Status9900.ST_C|Status9900.ST_O);
if ((dst & src & 0x8000) != 0
|| (dst & 0x8000 ^ src & 0x8000) != 0 && (res & 0x8000) == 0) {
bits |= Status9900.ST_C;
}
if ( ((~dst & ~src & res | dst & src & ~res) & 0x8000) != 0) {
bits |= Status9900.ST_O;
}
lastval = res; lastcmp = 0;
}
/*
Set laeco for subtract, preserve none
*/
public void set_SUB_LAECO(short dst, short src) {
set_ADD_LAECO(dst, (short) (1+~src));
if (src==0 || src==(short)0x8000) {
bits |= Status9900.ST_C;
}
}
/*
Set laeco for add, preserve none (BYTE)
*/
public void set_ADD_BYTE_LAECOP(byte dst, byte src) {
byte res = (byte)(dst+src);
bits &= ~(Status9900.ST_C|Status9900.ST_O|Status9900.ST_P);
if ( (dst & src & 0x80) != 0 ||
(dst & 0x80 ^ src & 0x80) != 0 && (res & 0x80) == 0 ) {
bits |= Status9900.ST_C;
}
if ( ((~dst & ~src & res | dst & src & ~res) & 0x80) != 0) {
bits |= Status9900.ST_O;
}
lastparity = res;
lastval = res; lastcmp = 0;
}
/*
Set laeco for subtract, preserve none (BYTE)
*/
public void set_SUB_BYTE_LAECOP(byte dst, byte src) {
set_ADD_BYTE_LAECOP(dst, (byte)(1+~src));
if (src==0 || (src & 0xff) == 0x80) {
bits |= Status9900.ST_C;
}
}
/*
For ABS and DIV
*/
public void set_O(boolean b) {
if (b) {
bits |= Status9900.ST_O;
} else {
bits &= ~Status9900.ST_O;
}
}
/*
For CMP
*/
public void set_CMP(short a, short b) {
lastval = a;
lastcmp = b;
}
/*
For CMP
*/
public void set_BYTE_CMP(byte a, byte b) {
lastval = a;
lastcmp = b;
}
/*
Right shift carries
*/
public void set_SHIFT_RIGHT_C(short a, short c) {
short mask= (short) (c != 0 ? 1 << c-1 : 0);
if ((a & mask) != 0) {
bits |= Status9900.ST_C;
} else {
bits &= ~Status9900.ST_C;
}
}
/*
Left shift overflow & status
*/
public void set_SHIFT_LEFT_CO(short a, short c) {
short mask = (short)(0x10000 >> c);
if ((a & mask) != 0) {
bits |= Status9900.ST_C;
} else {
bits &= ~Status9900.ST_C;
}
if (((a ^ a<<c) & 0x8000) != 0) {
bits |= Status9900.ST_O;
} else {
bits &= ~Status9900.ST_O;
}
}
/*
For XOP
*/
public void set_X() {
bits |= Status9900.ST_X;
}
/*
* for LIMI
*/
public void setIntMask(int mask) {
bits = (short) (bits & ~0xf | mask & 0xf);
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#isLT()
*/
public boolean isLT() {
return lastval < lastcmp;
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#isLE()
*/
public boolean isLE() {
return (lastval & 0xffff) <= (lastcmp & 0xffff);
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#isL()
*/
public boolean isL() {
return (lastval & 0xffff) < (lastcmp & 0xffff);
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#isEQ()
*/
public boolean isEQ() {
return lastval == lastcmp;
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#isNE()
*/
public boolean isNE() {
return lastval != lastcmp;
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#isHE()
*/
public boolean isHE() {
return (lastval & 0xffff) >= (lastcmp & 0xffff);
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#isGT()
*/
public boolean isGT() {
return lastval > lastcmp;
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#isH()
*/
public boolean isH() {
return (lastval & 0xffff) > (lastcmp & 0xffff);
}
/* (non-Javadoc)
* @see v9t9.engine.cpu.Status#isC()
*/
public boolean isC() {
return (bits & Status9900.ST_C) != 0;
}
public boolean isO() {
return (bits & Status9900.ST_O) != 0;
}
public boolean isP() {
return isOddParity(lastparity);
}
static final byte parity[] = { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1,
1, 0 };
static boolean isOddParity(byte val) {
// determine parity of an 8-bit byte, 0=even, 1=odd
return ((parity[(val & 0xf)] ^ parity[val >> 4 & 0xf]) & 1) != 0;
}
/**
* @return
*/
public int getIntMask() {
return bits & ST_INTLEVEL;
}
/** Get the status bits that 'st' (st_XXX) modifies */
public static int getStatusBits(int st) {
switch (st) {
case IStatus.stset_NONE: return 0;
case IStatus.stset_ALL: return 0xffff;
case IStatus.stset_INT: return ST_INTLEVEL;
case stset_XOP: return ST_X;
case stset_CMP: return ST_L + ST_A + ST_E;
case stset_BYTE_CMP: return ST_L + ST_A + ST_E + ST_P;
case stset_LAE: return ST_L + ST_A + ST_E;
case stset_LAEO: return ST_L + ST_A + ST_E + ST_O;
case stset_O: return ST_O;
case stset_E: return ST_E;
case stset_BYTE_LAEP: return ST_L + ST_A + ST_E + ST_P;
case stset_SUB_LAECO: return ST_L + ST_A + ST_E + ST_C + ST_O;
case stset_SUB_BYTE_LAECOP: return ST_L + ST_A + ST_E + ST_C + ST_O + ST_P;
case stset_ADD_LAECO: return ST_L + ST_A + ST_E + ST_C + ST_O;
case stset_ADD_BYTE_LAECOP: return ST_L + ST_A + ST_E + ST_C + ST_O + ST_P;
case stset_SHIFT_RIGHT_C: return ST_C;
case stset_SHIFT_LEFT_CO: return ST_C + ST_O;
case stset_DIV_O: return ST_O;
case stset_LAE_1: return ST_L + ST_A + ST_E;
case stset_BYTE_LAEP_1: return ST_L + ST_A + ST_E + ST_P;
case stset_ADD_LAECO_REV:
case stset_ADD_LAECO_REV_1:
case stset_ADD_LAECO_REV_2:
case stset_ADD_LAECO_REV_N1:
case stset_ADD_LAECO_REV_N2:
return ST_L + ST_A + ST_E + ST_C + ST_O;
default: throw new AssertionError("bad st_XXX value");
}
}
}