ARM ARM1176JZF-S User Manual

VFP Exception Handling
ARM DDI 0301H Copyright © 2004-2009 ARM Limited. All rights reserved. 22-22
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22.12.3 FMUL and FNMUL
Detection of a potential exception is based on the initial product exponent, that is the sum of the
multiplicand and multiplier exponents. Table 22-9 lists the result for specific values of the initial
product exponent. The exponent values in Table 22-9 are in biased format. The exponent can be
incremented by a significand overflow condition, and this is the cause for the additional bounce
values near the real overflow threshold. The one additional value in the bounce range makes the
FMUL and FNMUL overflow detection ranges identical to those in Table 22-8 on page 22-21.
22.12.4 FMAC, FMSC, FNMAC, and FNMSC
The FMAC family of operations adds to the potential overflow range by generating significand
values from zero up to but not including four. In this case it is possible for the final exponent to
require incrementing by two to normalize the significand.
The bounce thresholds for the FADD family in Table 22-8 on page 22-21 and for the FMUL
family in Table 22-9 incorporate this additional factor. Those ranges are used to detect potential
exceptions for the FMAC family.
Table 22-9 FMUL family bounce thresholds
Initial product exponent value
Float value
Condition in full-compliance mode
DP
a
a. DP = double-precision.
SP
b
b. SP = single-precision.
SP DP
>
0x7FF - DP overflow - Bounce
0x7FF - DP NaN or infinity - Bounce
0x7FE - DP maximum normal - Bounce
0x7FD - DP normal - Bounce
0x7FC - DP normal - Normal
>
0x47F > 0xFF SP overflow Bounce Normal
0x47F 0xFF SP NaN or infinity Bounce Normal
0x47E 0xFE SP maximum normal Bounce Normal
0x47D 0xFD SP normal Bounce Normal
0x47C 0xFC SP normal Normal Normal
0x3FF 0x7F e = 0 bias value Normal Normal
0x381 0x01 SP normal Normal Normal
0x380 0x00 SP subnormal Bounce Normal
<
0x380 < 0x00 SP underflow Bounce Normal
0x001 - DP normal - Normal
0x000 - DP subnormal - Bounce
<
0x000 - DP underflow - Bounce

ARM ARM1176JZF-S Specifications

General

Brand	ARM
Model	ARM1176JZF-S
Category	Computer Hardware
Language	English