_bitio.cpp

00001 #include "mbed.h"
00002 #include "string"
00003 #include "_bitio.h"
00004 
00005 
00006 FILE *infp, *outfp;
00007 int  getcount, putcount;
00008 Uint bitbuf;
00009 
00010 void init_bit_o(void)
00011 {
00012     putcount = 8; bitbuf = 0;
00013 }
00014 
00015 void init_bit_i(void)
00016 {
00017     getcount = 0; bitbuf = 0;
00018 }
00019 
00020 
00021 Uint getbit(void)
00022 {
00023     int flag;
00024     if (--getcount >= 0)  return (bitbuf >> getcount) & 1U;
00025     getcount = 7; 
00026     if((flag = fgetc(infp))==EOF)return OVERRUN;
00027     else bitbuf = flag;
00028     return (bitbuf >> 7) & 1U;
00029 }
00030 
00031 Uint getbits(int n)
00032 {
00033     Uint x = 0;
00034     if (n < 1 || 25 < n)  return 0;
00035     while (n > getcount) {
00036         n -= getcount;
00037         x |= rightbits(getcount, bitbuf) << n;
00038         bitbuf = fgetc(infp); getcount = 8;
00039     }
00040     getcount -= n;
00041     return x | rightbits(n, bitbuf >> getcount);
00042 }
00043 
00044 
00045 void putbit(Uint bit)
00046 {
00047     putcount--;
00048     if (bit != 0)  bitbuf |= (1 << putcount);
00049     if (putcount == 0) {
00050         if (fputc(bitbuf, outfp) == EOF)  error("can't write\r\n");
00051         bitbuf = 0; putcount = 8;
00052     }
00053 }
00054 
00055 
00056 void putbits(int n, Uint x)
00057 {
00058     if (n < 1 || 25 < n)  return;
00059     while (n >= putcount) {
00060         n -= putcount;
00061         bitbuf |= rightbits(putcount, x >> n);
00062         if (fputc(bitbuf, outfp) == EOF)  error("cant write\r\n");
00063         bitbuf = 0U; putcount = 8;
00064     }
00065     putcount -= n;
00066     bitbuf |= rightbits(n, x) << putcount;
00067 }