view docs/ccguide/crc.refentry @ 2321:6a5ada3e2666

added DWINIT op code, dw3 now sends on init just before installing VIRQ
author aaronwolfe
date Wed, 06 Jan 2010 01:55:30 +0000
parents c0da1728ed5b
children
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<refentry id="crc">
<refnamediv>
<refname>Crc</refname>
<refpurpose>compute a cyclic redundancy count</refpurpose>
</refnamediv>

<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
  <funcdef><function>crc</function></funcdef>
  <paramdef>char *<parameter>start</parameter></paramdef>
  <paramdef>int <parameter>count</parameter></paramdef>
  <paramdef>char <parameter>accum</parameter>[3]</paramdef>
</funcprototype>
</funcsynopsis>

</refsynopsisdiv>

<refsect1><title>Assembler Equivalent</title>
<para>
os9 F$CRC
</para>
</refsect1>

<refsect1><title>Description</title>
<para>
This call accumulates a crc into a three byte array at "accum"
for "count" bytes starting at "start". All three bytes of
"accum" should be initialized to 0xff before the first call to
"crc()". However, repeated calls can be subsequently made to
cover an entire module. If the result is to be used as an OS-9
module crc, it should have its bytes complemented before
insertion at the end of the module.
</para>
</refsect1>
</refentry>