Custom Script Programming

DESCRIPTION OF STREAM FUNCTIONS

stream_create

STREAM *stream_create(char* filename,int read,int append);

Creates a file stream, a tcp stream, an udp stream a syslog stream or a RS232/RS485 stream (see example 2 and example 3)

filename:

read: If stream is a file stream: 1 = read file; 0 = write file
append: 1 = append text to file; 0 = overwrite text in file

stream_printf

void stream_printf(STREAM* stream,char *format, …);

Writes to the output buffer of the specified stream a sequence of data formatted as the format argument specifies. After the format parameter, the function expects at least as many additional arguments as specified in format.

int stream_write(STREAM* stream,void* ptr,int size);

Writes an array of size elements, from the block of memory pointed by ptr to the to the output buffer of the specified stream (see example 2).

The postion indicator of the stream is advanced by the total number of bytes written.
The total number of elements successfully written is returned. If this number differs from the size parameter, it indicates an error.

stream_flush

void stream_flush(STREAM* stream);

If the given stream is a file stream and the file was opened for writing any unwritten data in the output buffer is written to the file (see example 2).

If the given stream is a tcp stream, an udp stream or a syslog stream any data in the output buffer is sent to the server.

stream_read

int stream_read(STREAM* stream,void* ptr,int size,int timeout);

Reads an array of size elements from the input buffer of the specified stream and stores them in the block of memory specified by ptr (see example 2).

The timeout is given in milliseconds. The postion indicator of the stream is advanced by the total amount of bytes read. The total number of elements successfully read is returned.

stream_readline

int stream_readline(STREAM* stream,void* ptr,int maxsize,int timeout);

If the given stream is a file stream the next line of the file is read.

The maximal number of elements to read is specified with parameter maxsize. The timeout is given in milliseconds.

stream_close

void stream_close(STREAM* stream)

Closes the specified stream and deallocates all memory used by the stream.

EXAMPLES

The examples should show how script programs can be created.

EXAMPLE 1: COMPUTING

This example shows how an own computing is done:
If a change on any input occurs, the value of input 1 multiplied with the value on input 2 plus the value on input 3 is given to output 1.
The formula is output as text on text output 1.

// write program here in PicoC
char szBuffer[128];
float f1,f2,f3,f4;
int nEvents;
while(TRUE)
{
nEvents = getinputevent();
if (nEvents & 0xe)
{
f1 = getinput(0);
f2 = getinput(1);
f3 = getinput(2);
f4 = f1 * f2 + f3;
setoutput(0,f4);
sprintf(szBuffer,”/ * %f + %f = %f”,f1,f2,f3,f4);
setoutputtext(0,szBuffer);
printf(szBuffer);
}
sleep(100);
}

EXAMPLE 2: WEBSITE DOWNLOAD PER TCP STREAM

This example shows how to download a website with a tcp stream and how to save the website in a file.

#define BUFF_SIZE 40000
#define RD_BLOCK_SIZE 128

STREAM* pTcpStream = stream_create(“/dev/tcp/www.w3.org/80”,0,0);   // create tcp stream
char* pTcpCmd = “GET / HTTP/1.1\r\nHost: www.w3.org\r\nUser-Agent: LoxLIVE [en]\r\nContent-Type: text/html; charset=utf-8\r\n\r\n”;
stream_write(pTcpStream,pTcpCmd,strlen(pTcpCmd));   // write to output buffer
stream_flush(pTcpStream);                           // flush output buffer
char szBuffer[BUFF_SIZE];
char szTmpBuffer[RD_BLOCK_SIZE];
int nCnt;
int nBytesReceived = 0;
int i = 0;
// read stream
do
{
nCnt = stream_read(pTcpStream,szTmpBuffer,RD_BLOCK_SIZE,4000);
if(nCnt > 0)
strncpy((char*)szBuffer+i*RD_BLOCK_SIZE,szTmpBuffer,nCnt);
nBytesReceived += nCnt;
i++;
}
while (nCnt > 0);
FILE* pw = fopen(“/w3.html”,”w”);       // open file
fprintf(pw,”%s”,szBuffer);          // write file
printf(“Bytes received: %d”,nBytesReceived);
fclose(pw);
stream_close(pTcpStream);

EXAMPLE 3: CONNECTING TO AN APC USV, IF APCUPSD IS USED ON THE PC

This example shows the actual load (AQ1), battery capacity (AQ2) as well as power failures (AQ3).

char* p,*pS;
char szBuffer[1500];
int nLen;
int bOnline = 0;
double dCharge,dLoad;
printf(“Start APC watch”);
while(TRUE)
{
STREAM* stream = stream_create(“/dev/tcp/192.168.1.9/3551″,0,0);
if (stream != NULL)
{
szBuffer[0] = 0;
szBuffer[1] = 6;
stream_write(stream,szBuffer,2);
stream_flush(stream);
stream_write(stream,”status”,6);
stream_flush(stream);
nLen = stream_read(stream,szBuffer,2,1000);
nLen = stream_read(stream,szBuffer,sizeof(szBuffer) – 1,1000);
stream_close(stream);
szBuffer[nLen] = 0;
szBuffer[nLen + 1] = 0;
//printf(“APC Len=%d”,nLen);
pS = szBuffer;
while(*pS)
{
p = strstr(pS,”STATUS   :”);
if (p != NULL)
{
p = strstr(pS,”STATUS   : ONLINE”);
if (p != NULL)
bOnline = 1;
else
bOnline = 0;
}
else
{
p = strstr(pS,”LOADPCT  :”);
if (p != NULL)
{
dLoad = batof(p + 11);
setoutput(0,dLoad);
}
else
{
p = strstr(pS,”BCHARGE  :”);
if (p != NULL)
{
dCharge = batof(p + 11);
setoutput(1,dCharge);
break;
}
}
}
pS += (strlen(pS) + 1);
}
if (bOnline)
{
setoutput(2,1);
//printf(“Power OK Charge: %f%% Load: %f%%”,dCharge,dLoad);
}
else
{
setoutput(2,0);
//printf(“Power lost Charge: %f%% Load: %f%%”,dCharge,dLoad);
}
}
else
printf(“APC no connection”);
sleeps(10);        // wait 10 seconds
}

EXAMPLE 4: READ FROM RS232 EXTENSION VIA RS232 STREAM

This example reads the bytes received from RS232 extension and puts it on text output 1. The total number of received bytes is put to the first analog output.

#define BUFF_SIZE 256

STREAM* pRs232Stream = stream_create(“/dev/tty/my_rs232_extension”,0,0);// create rs232 stream
char szBuffer[BUFF_SIZE];
int nCnt;
int nBytesReceived = 0;
while(1)
{
nCnt = stream_read(pRs232Stream,szBuffer,BUFF_SIZE,100);    // read stream
nBytesReceived += nCnt;
setoutput(0,(float)nBytesReceived);
setoutputtext(0,szBuffer);
sleep(100);
}

picoc is published under the “New BSD License”.
http://www.opensource.org/licenses/bsd-license.php

Copyright (c) 2009, Zik Saleeba
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

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• Neither the name of the Zik Saleeba nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

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