ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

FPInfinity()
// ============
Application Level Programmers’ Model
bits(N) FPInfinity(bit sign, integer N)
assert N == 16 || N == 32 || N == 64;
if N == 16 then
return sign : ‘11111 0000000000’;
elsif N == 32 then
return sign : ‘11111111 00000000000000000000000’;
else
return sign : ‘11111111111 0000000000000000000000000000000000000000000000000000’;
// FPDefaultNaN()
// ==============
bits(N) FPDefaultNaN(integer N)
assert N == 16 || N == 32 || N == 64;
if N == 16 then
return ‘0 11111 1000000000’;
elsif N == 32 then
return ‘0 11111111 10000000000000000000000’;
else
return ‘0 11111111111 1000000000000000000000000000000000000000000000000000’;
Note
This definition of FPDefaultNaN() applies to VFPv3 and VFPv3U. For VFPv2, the sign bit of the result is a
single-bit UNKNOWN value, instead of 0.
Negation and absolute value
The floating-point negation and absolute value operations only affect the sign bit. They do not treat NaN
operands specially, nor denormalized number operands when flush-to-zero is selected.
// FPNeg()
// =======
bits(N) FPNeg(bits(N) operand)
assert N == 32 || N == 64;
return NOT(operand) : operand;
// FPAbs()
// =======
bits(N) FPAbs(bits(N) operand)
assert N == 32 || N == 64;
return ‘0’ : operand;
ARM DDI 0406B Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. A2-47