INTERFACE--------------------------------------------------- IEEE classification ---FPU ;
TYPE
FPClass = { SignalingNaN, QuietNaN,
PosInfinity, NegInfinity,
PosNormal, NegNormal,
PosDenormal, NegDenormal,
PosZero, NegZero };
<*EXTERNAL fpclass*> PROCEDURE LongClass (x: LONGREAL): INTEGER;
returns the IEEE defined class of its argument -- from ieeefp.h
----------------------------------------------- control/status register ---
From sys/fpu.h
TYPE
Flag = BITS 1 FOR BOOLEAN;
TYPE
ControlStatus = RECORD
reserved0 : BITS 7 FOR [0..127];
flush : Flag;
condition : Flag; (* result of most recent compare instruction *)
reserved1 : BITS 5 FOR [0..31];
(* exceptions that occurred during the most recent instruction *)
ex_unimplemented : Flag;
ex_invalid : Flag;
ex_divide0 : Flag;
ex_overflow : Flag;
ex_underflow : Flag;
ex_inexact : Flag;
(* trap enable flags for the exceptions *)
en_invalid : Flag;
en_divide0 : Flag;
en_overflow : Flag;
en_underflow : Flag;
en_inexact : Flag;
(* "sticky" bits, only reset by writing the control register *)
se_invalid : Flag;
se_divide0 : Flag;
se_overflow : Flag;
se_underflow : Flag;
se_inexact : Flag;
rounding_mode : BITS 2 FOR RoundingMode;
END;
TYPE
RoundingMode = { ToNearest, ToZero, ToPlusInfinity, ToMinusInfinity };
<*EXTERNAL get_fpc_csr*>
PROCEDURE GetStatus (): INTEGER(*ControlStatus*);
returns the current setting of the floating point control registers
<*EXTERNAL set_fpc_csr*> PROCEDURE SetStatus (new: INTEGER): INTEGER(*ControlStatus*);
sets the floating point control registers and returns their previous state
From <ieeefp.h>
<*EXTERNAL fpgetround*> PROCEDURE GetRounding (): INTEGER(*RoundingMode*);
returns the current rounding mode
<*EXTERNAL fpsetround*> PROCEDURE SetRounding(new: INTEGER): INTEGER(*RoundingMode*);
sets the rounding mode and returns its previous value
From <math.h>
<*EXTERNAL isnan*> PROCEDURE IsNaN (x: LONGREAL): BOOLEAN;
return 1 if x is NaN, 0 otherwise.
<*EXTERNAL copysign*> PROCEDURE CopySign (x, y: LONGREAL): LONGREAL;
return 'x' with the sign of 'y'.
<*EXTERNAL drem*> PROCEDURE Remainder (x, y: LONGREAL): LONGREAL;
returns the remainder r := x - n*y where n is the integer nearest the exact value of x/y. Additionally if |n-x/y|=1/2, then n is even. Consequently the remainder is computed exactly and |r| < |y|/2. Remainder (x, 0.0) and Remainder (infinity, y) produce NaN.
<*EXTERNAL finite*> PROCEDURE IsFinite (x: LONGREAL): BOOLEAN;
= 1 if -infinity < x < +infinity, otherwise = 0
<*EXTERNAL logb*> PROCEDURE BinaryLog (x: LONGREAL): LONGREAL;
for x finite, non-zero, and above the underflow threshold, returns the integer valued floating-point number n, such that 1 < ABS (x) / (2^n) < 2. Note that BinaryLog (+infinity) = +infinity, and BinaryLog (0) = -infinity (and causes a division-by-zero error).
<*EXTERNAL ldexp*> PROCEDURE scalb (x: LONGREAL; n: INTEGER): LONGREAL;
returns x * (2^n)
<*EXTERNAL*> PROCEDURE sqrt (x: LONGREAL): LONGREAL;
returns sqrt (x)
END FPU.