
<<Basics.mesa>>
<<last edited by Levin on September 20, 1983 11:00 am>>

DIRECTORY
PrincOps USING [
zAND, zDCOMP, zDIV, zDUCOMP, zINC, zLDIV, zLIN1, zMUL, zOR, zPUSH, zSHIFT, zXOR];

Basics: CEDAR DEFINITIONS =

BEGIN

OPEN PrincOps;

<<Commonly-used types and values>>

bytesPerWord, charsPerWord: NAT = 2;
bitsPerByte, bitsPerChar: NAT = 8;
bitsPerWord: NAT = bitsPerByte*bytesPerWord;

logBitsPerByte, logBitsPerChar: NAT = --LogBase2[bitsPerByte]--3;
logBytesPerWord, logCharsPerWord: NAT = --LogBase2[bytesPerWord]--1;
logBitsPerWord: NAT = logBitsPerByte + logBytesPerWord;

Byte, BYTE: TYPE = [0..377B];
Word: TYPE = WORD;

LongNumber: TYPE = MACHINE DEPENDENT RECORD [
SELECT OVERLAID * FROM
lc => [lc: LONG CARDINAL],
li => [li: INT],
num => [lowbits, highbits: CARDINAL],
bytes => [lh, ll, hh, hl: BYTE],
ENDCASE];

BytePair: TYPE = MACHINE DEPENDENT RECORD [high, low: BYTE];

Comparison: TYPE = MACHINE DEPENDENT {less(0), equal(1), greater(2)};

RefSeq: TYPE = RECORD [length: NAT, elements: SEQUENCE maxLength: NAT OF REF ANY];

RawMemory: TYPE = RECORD [SEQUENCE COMPUTED CARDINAL OF WORD];

UnsafeBlock: TYPE = RECORD [
base: LONG POINTER TO PACKED ARRAY [0..0) OF CHAR _ NIL,
startIndex: INT _ 0,
count: INT _ 0
];
<<An UnsafeBlock describes the byte sequence [base[startIndex]..base[startIndex]+base[count]).>>

<<Arithmetic utilities>>
<<>>
CompareLC, CompareCard: PROC [a, b: LONG CARDINAL] RETURNS [Comparison] =
TRUSTED MACHINE CODE {zDUCOMP; zINC};

CompareINT: PROC [a, b: INT] RETURNS [Comparison] = TRUSTED MACHINE CODE
{zDCOMP; zINC};

DIVMOD: PROC [num, den: CARDINAL] RETURNS [quotient, remainder: CARDINAL] =
TRUSTED MACHINE CODE {zDIV; zPUSH};

LDIVMOD: PROC [numlow: WORD, numhigh: CARDINAL, den: CARDINAL]
RETURNS [quotient, remainder: CARDINAL] = TRUSTED MACHINE CODE {zLDIV; zPUSH};

LongMult: PROC [CARDINAL, CARDINAL] RETURNS [product: LONG CARDINAL] =
TRUSTED MACHINE CODE {zMUL; zPUSH};

LongDiv: PROC [num: LONG CARDINAL, den: CARDINAL] RETURNS [CARDINAL] =
TRUSTED MACHINE CODE {zLDIV};

LongDivMod: PROC [num: LONG CARDINAL, den: CARDINAL]
RETURNS [quotient, remainder: CARDINAL] = TRUSTED MACHINE CODE {zLDIV; zPUSH};

<<Logic utilities>>
<<>>
BitOp: TYPE = SAFE PROC [CARDINAL, CARDINAL] RETURNS [CARDINAL];

BITAND: BitOp =
TRUSTED MACHINE CODE {zAND};

BITOR: BitOp =
TRUSTED MACHINE CODE {zOR};

BITXOR: BitOp =
TRUSTED MACHINE CODE {zXOR};

BITNOT: SAFE PROC [CARDINAL] RETURNS [CARDINAL] =
TRUSTED MACHINE CODE {zLIN1; zXOR};

BITSHIFT: SAFE PROC [value: CARDINAL, count: INTEGER] RETURNS [CARDINAL] =
TRUSTED MACHINE CODE {zSHIFT};

<<Field Extraction>>

LowHalf: PROC [n: LONG CARDINAL] RETURNS [CARDINAL] = TRUSTED INLINE
{RETURN[LOOPHOLE[n, LongNumber].lowbits]};

HighHalf: PROC [n: LONG CARDINAL] RETURNS [CARDINAL] = TRUSTED INLINE
{RETURN[LOOPHOLE[n, LongNumber].highbits]};

LowByte: PROC [n: CARDINAL] RETURNS [CARDINAL] = TRUSTED INLINE
{RETURN[LOOPHOLE[n, BytePair].low]};

HighByte: PROC [n: CARDINAL] RETURNS [CARDINAL] = TRUSTED INLINE
{RETURN[LOOPHOLE[n, BytePair].high]};

END.