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* update information on floating point (extended and single clarifications)

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carl 2002-12-04 21:49:30 +00:00
parent 8744523b9b
commit 7aa569d748
1 changed files with 11 additions and 8 deletions
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docs/prog.tex
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@ -3469,7 +3469,8 @@ value is stored as a 4 byte value (longword).
Floating point type sizes and mapping vary from one Floating point type sizes and mapping vary from one
processor to another. Except for the Intel 80x86 processor to another. Except for the Intel 80x86
architecture, the \var{extended} type maps to the IEEE architecture, the \var{extended} type maps to the IEEE
double type. double type if a hardware floating point coprocessor
is present.
\begin{FPCltable}{lr}{Processor mapping of real type}{RealMapping} \begin{FPCltable}{lr}{Processor mapping of real type}{RealMapping}
Processor & Real type mapping\\ Processor & Real type mapping\\
@ -3489,7 +3490,9 @@ point value.
The \var{single} type occupies 4 bytes of storage space, The \var{single} type occupies 4 bytes of storage space,
and its memory structure is the same as the IEEE-754 single and its memory structure is the same as the IEEE-754 single
type. type. This type is the only type which is guaranteed to
be available on all platforms (either emulated via software
or directly via hardware).
The memory format of the \var{single} format looks like The memory format of the \var{single} format looks like
\begin{htmlonly} \begin{htmlonly}
@ -3540,7 +3543,7 @@ like what is shown in \seefig{doubleformat}.
On processors which do not support co-processor operations (and which have On processors which do not support co-processor operations (and which have
the \{\$E-\} switch), the \var{double} type does not exist. the \{\$E+\} switch), the \var{double} type does not exist.
@ -3551,11 +3554,11 @@ takes up 10 bytes of memory space. For more information
on the extended type consult the Intel Programmer's reference. on the extended type consult the Intel Programmer's reference.
For all other processors which support floating point operations, For all other processors which support floating point operations,
the \var{extended} type is a nickname for the \var{double} type. the \var{extended} type is a nickname for the type which supports
It has the same format and size as the \var{double} type. On the most precision, this is usually the \var{double} type.
processors which do not support co-processor operations (and which have On processors which do not support co-processor operations (and which have
the \{\$E-\} switch), the the \{\$E+\} switch), the \var{extended} type usually maps to the
\var{extended} type does not exist. \var{single} type.
\subsubsection{comp} \subsubsection{comp}