ZeroMQ baseband publisher

zmq-pub.c

/*
to source IQ baseband samples from SX1255 over I2S, run this:
arecord -t raw -f S32_LE -r 192000 -c 2 --device="hw:0,1" | ./zmq-pub

note: you need to enable I2S overlay (acting as a slave)
this one works good: https://github.com/AkiyukiOkayasu/RaspberryPi_I2S_Slave
note: setting the rate to 192k isn't really effective, the actual rate is 125k (governed by the I2S master - SX1255)
*/

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <zmq.h>

#define SAMP_FLOAT

void *zmq_ctx;
void *bsb_downlink;

int rcvd;
uint8_t inp[100000];

int main(void)
{
	zmq_ctx = zmq_ctx_new();
	bsb_downlink = zmq_socket(zmq_ctx, ZMQ_PUB);

	printf("ZeroMQ ");
	if(zmq_bind(bsb_downlink, "tcp://*:17017")==0)
		printf("OK\n");
	else
		printf("ERROR\n");

	while(1)
	{
		ioctl(STDIN_FILENO, FIONREAD, &rcvd);
		if(rcvd>0)
		{
			if(read(STDIN_FILENO, inp, rcvd)==rcvd)
			{
				#if defined(SAMP_INT32) //signed 32-bit ints
				zmq_send(bsb_downlink, (char*)inp, rcvd, 0);
				#elif defined(SAMP_FLOAT) //32-bit floats
				float val[100000];
				memset(val, 0, sizeof(val));
				for(int j=0; j<rcvd; j+=8)
				{
					int32_t i=0, q=0;
					memcpy((uint8_t*)&i, &inp[0+j], 4);
					memcpy((uint8_t*)&q, &inp[4+j], 4);
					val[(j/8)*2]  =i/(float)0x7FFFFFFFL;
					val[(j/8)*2+1]=q/(float)0x7FFFFFFFL;
				}
				zmq_send(bsb_downlink, (char*)val, rcvd, 0);
				#endif
			}
		}
	}

	return 0;
}