$ cat 879430.cpp 
#include <stdio.h>

int *decode(unsigned char *buf, int buflen) {
	static int retval[201];
	int tmp=0;
	int mask=0;
	int *outbuf=retval;
	unsigned char *end=buf+buflen;
	while (buf < end) {
		int t=*buf & 0xc0;
	
		if (t==0xc0) {
			tmp =*buf++<<16;
			tmp|=*buf++<<8;
			tmp|=*buf++;
			mask=0x3fffff;
		}
		else if (t==0x80) {
			tmp =*buf++<<8;
			tmp|=*buf++;
			mask=0x3fff;
		}
		else {
			tmp =*buf++;
			mask=0x7f;
		}
		*outbuf++ = tmp&mask;
	}
	*outbuf++ = -1; // sentinel value: EOList
	return retval;
}

unsigned char foo[] = {
	0x55,			// 85
	0xaa, 0xaa,		// 10922
	0xcc, 0xcc, 0xcc,	// 838860
	0
};

int main( void ) {
	int *t = decode(foo, sizeof(foo));
	while (*t != -1) {
		printf("0x%06x  %7u\n", *t, *t);
		t++;
	}
	return 1;
}
$ gcc 879430.cpp  -lstdc++

$ ./a.out
0x000055       85
0x002aaa    10922
0x0ccccc   838860
0x000000        0