view docs/ccguide/crc.refentry @ 3140:03b580a02945

Allow CoCo3FPGA-specific build of superdesc.asm Added new conditional CC3FPGA and code to "level1/modules/superdesc.asm" to reflect changes needed to build the new SD card descriptors for the Coco3FPGA.
author Bill Pierce <merlinious999@gmail.com>
date Sat, 04 Feb 2017 11:06:26 +0100
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>