EPICS_driver_modules/StreamDevice
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checksums after regsub must check original input

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zimoch
2025-05-27 16:40:08 +02:00
parent 9080d6ca8e
commit f61e6404f5
5 changed files with 42 additions and 10 deletions
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12
docs/formats.html
View File

@ -485,6 +485,12 @@ than 9.
<p>
This is not a normal "converter", because no user data is converted.
Instead, a checksum is calculated from the input or output.
<span class="new">
Any pre-processing of input, e.g. by the <a href="#regsub">regsub</a> converter
if ignored for the calculation of the checksum.
</span>
</p>
<p>
The <em>width</em> field is the byte number from which to start
calculating the checksum.
Default is 0, i.e. the first byte of the input or output of the current
@ -711,10 +717,14 @@ However if an empty string is matched, searching advances by 1 character in orde
avoid matching the same empty string again.</span>
</p>
<p>
In input this converter pre-processes data received from the device before
In input, this converter pre-processes data received from the device before
following converters read it.
Converters preceding this one will read unmodified input.
Thus place this converter before those whose input should be pre-processed.
<span class="new">
However, <a href="#chksum">checksum</a> converters will always use the unmodified
input as sent by the device because the modified input would not match the checksum.
</span>
</p>
<p>
In output it post-processes data already formatted by preceding converters

12
src/ChecksumConverter.cc
View File

@ -682,13 +682,13 @@ static uint32_t mask[5] = {0, 0xFF, 0xFFFF, 0xFFFFFF, 0xFFFFFFFF};
class ChecksumConverter : public StreamFormatConverter
{
int parse (const StreamFormat&, StreamBuffer&, const char*&, bool);
int parse (const StreamFormat&, StreamBuffer&, const char*&, bool scanFormat);
bool printPseudo(const StreamFormat&, StreamBuffer&);
ssize_t scanPseudo(const StreamFormat&, StreamBuffer&, size_t& cursor);
};
int ChecksumConverter::
parse(const StreamFormat&, StreamBuffer& info, const char*& source, bool)
parse(const StreamFormat&, StreamBuffer& info, const char*& source, bool scanFormat)
{
const char* p = strchr(source, '>');
if (!p)
@ -742,7 +742,7 @@ parse(const StreamFormat&, StreamBuffer& info, const char*& source, bool)
info.append(&xorout, sizeof(xorout));
info.append(fnum);
source = p+1;
return pseudo_format;
return scanFormat ? needs_original_format : pseudo_format;
}
}
@ -847,7 +847,7 @@ scanPseudo(const StreamFormat& format, StreamBuffer& input, size_t& cursor)
else length = 0;
}
debug("ChecksumConverter %s: input to check: \"%s\n",
debug("ChecksumConverter %s: input to check: \"%s\"\n",
checksumMap[fnum].name, input.expand(start,length)());
uint8_t nDigits =
@ -859,8 +859,8 @@ scanPseudo(const StreamFormat& format, StreamBuffer& input, size_t& cursor)
if ((ssize_t)( input.length() - cursor ) < expectedLength)
{
debug("ChecksumConverter %s: Input '%s' too short for checksum\n",
checksumMap[fnum].name, input.expand(cursor)());
debug("ChecksumConverter %s: Input '%s' too short (%zu-%zu<%zu) for checksum\n",
checksumMap[fnum].name, input.expand(cursor)(), input.length(), cursor, expectedLength);
return -1;
}

16
src/StreamCore.cc
View File

@ -1184,6 +1184,7 @@ matchInput()
char command;
const char* fieldName = NULL;
StreamBuffer formatstring;
ssize_t delta = 0;
consumedInput = 0;
@ -1218,7 +1219,7 @@ normal_format:
debug("StreamCore::matchInput(%s): format = \"%%%s\"\n",
name(), formatstring());
if (fmt.flags & skip_flag || fmt.type == pseudo_format)
if (fmt.flags & skip_flag || fmt.type == pseudo_format || fmt.type == needs_original_format)
{
long ldummy;
double ddummy;
@ -1240,9 +1241,20 @@ normal_format:
scanString(fmt, inputLine(consumedInput), NULL, size);
break;
case pseudo_format:
// pass complete input
// pass complete input line for scan and/or re-write
size = inputLine.length();
consumed = StreamFormatConverter::find(fmt.conv)->
scanPseudo(fmt, inputLine, consumedInput);
delta += inputLine.length() - size; // track length changes
debug("after rewrite delta=%zi\n", delta);
break;
case needs_original_format:
// pass original input with adjusted current position
debug("before checksum delta=%zi\n", delta);
consumedInput -= delta; // correct for length changes
consumed = StreamFormatConverter::find(fmt.conv)->
scanPseudo(fmt, inputBuffer, consumedInput);
consumedInput += delta;
break;
default:
error("INTERNAL ERROR (%s): illegal format.type 0x%02x\n",

3
src/StreamFormat.h
View File

@ -42,7 +42,8 @@ typedef enum {
enum_format,
double_format,
string_format,
pseudo_format
pseudo_format,
needs_original_format
} StreamFormatType;
extern const char* StreamFormatTypeStr[];

9
streamApp/tests/testChecksum
View File

@ -256,6 +256,9 @@ set protocol {
out "bitsum8 %s %#-9.1<bitsum8>"; in "bitsum8 %=s %#-9.1<bitsum8>";
out "bitsum16 %s %#-9.1<bitsum16>"; in "bitsum16 %=s %#-9.1<bitsum16>";
out "bitsum32 %s %#-9.1<bitsum32>"; in "bitsum32 %=s %#-9.1<bitsum32>";
# Check combination of regsub and checksum. Always check what the device sees.
out "crc8 %s%#/[0-9]{2}/&:/ %9.1<crc8>"; in "crc8 %#/[0-9]{2}/&:/%s %9.1<crc8>"; out "%s";
out "DONE";
}
}
@ -740,6 +743,12 @@ assure "bitsum16 123456789 \x32\x31\x30\x30\n"
send "bitsum16 123456789 \x32\x31\x30\x30\n"
assure "bitsum32 123456789 \x32\x31\x30\x30\x30\x30\x30\x30\n"
send "bitsum32 123456789 \x32\x31\x30\x30\x30\x30\x30\x30\n"
# check regsub and checksums
assure "crc8 12:34:56:78:9 \x07\n" ;# modified output string and checksum
send "crc8 123456789 \xF4\n" ;# original input string and checksum
assure "12:34:56:78:9\n" ;# modified input string
assure "DONE\n"
finish