[Cyan]<Cedar6.0>Compiler>IeeeFloat.mesa!3

IeeeFloat.mesa - adaptation of Real.mesa+Ieee.mesa for compiler use

Satterthwaite, April 16, 1986 3:03:48 pm PST

Russ Atkinson (RRA) March 6, 1985 10:11:12 pm PST

Real: DEFINITIONS = {

extended format

NumberType: TYPE = {normal, zero, infinity, nan};

Extended: TYPE = RECORD [

type: NumberType,

sign: BOOL,

exp: INTEGER,

frac: LONG CARDINAL];

modes

RoundingMode: TYPE = {rn, rz, rm, rp};

rn: Round to nearest (unbiased)

rz: Round to zero (truncate)

rp: Round to plus infinity (round up)

rm: Round to minus infinity (round down)

NormalizationMode: TYPE = {warning, normalizing};

Mode: TYPE = RECORD [

nm: NormalizationMode ← warning,

round: RoundingMode ← rn];

Constants

PlusZero: REAL = LOOPHOLE[(00000000000b).LONG];

MinusZero: REAL = LOOPHOLE[20000000000b];

PlusInfinity: REAL = LOOPHOLE[17740000000b];

MinusInfinity: REAL = LOOPHOLE[37740000000b];

TrapNonTrappingNaN: LONG CARDINAL = (1).LONG;

TrapTrappingNaN: LONG CARDINAL = (2).LONG;

Exceptions

Flag: TYPE = BOOL ← FALSE;

Exception: TYPE = {

fixOverflow, inexactResult, invalidOperation, divisionByZero, overflow, underflow};

ExceptionFlags: TYPE = PACKED ARRAY Exception OF Flag;

NoExceptions: ExceptionFlags = ALL[FALSE];

Operations

RealException: SIGNAL [flags: ExceptionFlags];

RealToExtended: PROC [a: REAL] RETURNS [Extended];

ExtendedToReal: PROC [e: Extended] RETURNS [REAL];

Abs: PROC [a: REAL] RETURNS [REAL];

Negate: PROC [a: REAL] RETURNS [REAL];

PairToReal: PROC [fr: LONG INTEGER, exp10: INTEGER] RETURNS [REAL];