view docs/ccguide/crc.refentry @ 3141:717ced83b885

coco3: Build SD card device descriptors for CoCo3FPGA Added "CC3FPGAFLAGS = $(AFLAGS) -DCC3FPGA=1 $(FLAGS)" to "level2/coco3/modules/makefile" for flagging Coco3FPGA specific features in modules sources. Added "llcoco3fpga", "ddsd0_coco3fpga", "sd0_coco3fpga", and "sd1_coco3fpga" to the "coco3/modules/makefile" - RBF section, which also now adds all to the "NITROS9/MODULES/RBF" on all disk images for building new Coco3FPGA disks from NitrOS9. Added new descriptor section to the "level2/coco3/modules/makefile" reflecting the new Coco3FPGA SD card descriptors and their flags.
author Bill Pierce <merlinious999@gmail.com>
date Sat, 04 Feb 2017 11:06:28 +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>