Help me understand this code plz

[iovecpsc]

#include <stdio.h>
 
 
 
char *HexToBin[16] =
 
{ "0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111",
 
  "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"
 
};
 
//---------------------------------------------------------------------------
 
#define UCHAR unsigned char
 
 
 
void print_bits(char *text, void *mem, unsigned char len)
 
{ unsigned char *addr;
 
  unsigned char i;
 
  unsigned int l;
 
 
 
  // *** Print Binary Value of Memory *** //
 
  printf(text);
 
  l = 0;
 
  for (addr=(UCHAR *)mem + len - 1; addr>=(UCHAR *)mem; addr--)
 
  {  printf("%4s", &HexToBin[*addr>>4][0]);
 
     printf("%4s ", &HexToBin[*addr % 16][0]);
 
     l <<= 8;
 
     l |= *addr;
 
  }
 
  printf("\n");
 
}
 
//---------------------------------------------------------------------------
 
char c;
 
unsigned char uc; 
 
//---------------------------------------------------------------------------   
 
void print_c(void)
 
{  printf("c = %c = %d = 0x%X", c, c, c);
 
   print_bits(" = ",&c, sizeof(c));
 
   printf("\n");  
 
}
 
//---------------------------------------------------------------------------
 
int main(void)
 
{    
 
   c = 65;  print_c();   
 
 
 
   for (c=7; c<=13; c++) print_c(); 
 
 
 
   c = '6';  print_c();
 
 
 
   c = '\'';  print_c();
 
 
 
   c = '\\';  print_c();
 
 
 
   uc = 200;  print_c();
 
 
 
   c = 200; print_c();
 
 
 
   getchar();
 
}
 

specifically the
the value of addressed is shifted four, that will give index for hextobin and then the value of address will be moduled by 16 to give another index for hex values. I am not seeing it.

 for (addr=(UCHAR *)mem + len - 1; addr>=(UCHAR *)mem; addr--)
 
  {  printf("%4s", &HexToBin[*addr>>4][0]);
 
     printf("%4s ", &HexToBin[*addr % 16][0]);
 
     l <<= 8;
 
     l |= *addr;
 
  }

[weaknessforcats]

What is this code supposed to do?

It's very messy and and the logic is convoluted and there are no comments to help anyone understand what is going on.

Perhaps you could provide more information about this code. I haven't got time to unravel it.

[GGnOrE]

I figured it out though, because my teacher showed me what it was supposed to do. It shows how differant things in c can be represent multiple ways. I was just trying to understand his algorithm and how he went about doing it. I got the values mixed it.but if you copy and paste it and run it, what the code is supposed to do is fairly straight forward.