AMX DESIGN XPRESS V 1.5 - PROGRAMMER GUIDE User's Guide download pdf (Page 161)

KwikNet Low Level Services

DAK

147

hton– hton–

ntoh– ntoh–

Purpose Convert Between Host and Network Endian Forms

Used by

n Task n ISP n Timer Procedure n Restart Procedure n Exit Procedure

Setup The macro definitions are in file KN_LIB.H.

C dependent, in-line assembly language expansions are in file KNZZZCC.H.

#include "KN_LIB.H"

Convert 32-bit values Convert 16-bit values

netlong = htonl(hostlong) netshort = htons(hostshort)

hostlong = ntohl(netlong) hostshort = ntohs(netshort)

Description Hostlong is any 32-bit value in host endian form.

Netlong is any 32-bit value in net endian form.

Hostshort is any 16-bit value in host endian form.

Netshort is any 16-bit value in net endian form.

If the KwikNet Library has been configured for big endian operation, these

macros do nothing since the input values require no conversion.

If the KwikNet Library has been configured for little endian operation, these

macros may expand to a function call, an in-line function expansion or a

series of C statements, depending upon which C compiler is being used.

The goal is always to ensure the fastest possible execution of these

frequently encountered macros. When possible, these macros have been

implemented using in-line assembly language statements generated by the

C compiler. In some cases, the macros generate calls to assembly

language functions of a form supported by the C compiler. As a last

resort, the macros expand to a series of in-line C statements.

Returns The input value converted to opposite endian form.

Restriction These macros can introduce side effects. Therefore, the macro parameters

must not use expressions which include operators such as

-- or ++ since

they always produce side effects. You must also avoid using expressions

which include function calls to fetch parameters if the functions can

introduce side effects.

Example See examples in the descriptions of

kn_cksum(), kn_dprintf() and

kn_fmt().

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AMX DESIGN XPRESS V 1.5 - PROGRAMMER GUIDE User's Guide Page 161