111 lines
2.4 KiB
C
111 lines
2.4 KiB
C
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#include <u.h>
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#include <libc.h>
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int
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dec32(uchar *dest, int ndest, char *src, int nsrc)
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{
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char *s, *tab;
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uchar *start;
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int i, u[8];
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if(ndest+1 < (5*nsrc+7)/8)
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return -1;
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start = dest;
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tab = "23456789abcdefghijkmnpqrstuvwxyz";
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while(nsrc>=8){
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for(i=0; i<8; i++){
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s = strchr(tab,(int)src[i]);
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u[i] = s ? s-tab : 0;
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}
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*dest++ = (u[0]<<3) | (0x7 & (u[1]>>2));
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*dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4));
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*dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1));
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*dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3));
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*dest++ = ((0x7 & u[6])<<5) | u[7];
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src += 8;
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nsrc -= 8;
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}
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if(nsrc > 0){
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if(nsrc == 1 || nsrc == 3 || nsrc == 6)
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return -1;
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for(i=0; i<nsrc; i++){
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s = strchr(tab,(int)src[i]);
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u[i] = s ? s-tab : 0;
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}
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*dest++ = (u[0]<<3) | (0x7 & (u[1]>>2));
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if(nsrc == 2)
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goto out;
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*dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4));
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if(nsrc == 4)
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goto out;
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*dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1));
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if(nsrc == 5)
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goto out;
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*dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3));
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}
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out:
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return dest-start;
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}
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int
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enc32(char *dest, int ndest, uchar *src, int nsrc)
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{
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char *tab, *start;
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int j;
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if(ndest <= (8*nsrc+4)/5 )
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return -1;
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start = dest;
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tab = "23456789abcdefghijkmnpqrstuvwxyz";
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while(nsrc>=5){
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j = (0x1f & (src[0]>>3));
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*dest++ = tab[j];
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j = (0x1c & (src[0]<<2)) | (0x03 & (src[1]>>6));
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*dest++ = tab[j];
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j = (0x1f & (src[1]>>1));
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*dest++ = tab[j];
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j = (0x10 & (src[1]<<4)) | (0x0f & (src[2]>>4));
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*dest++ = tab[j];
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j = (0x1e & (src[2]<<1)) | (0x01 & (src[3]>>7));
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*dest++ = tab[j];
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j = (0x1f & (src[3]>>2));
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*dest++ = tab[j];
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j = (0x18 & (src[3]<<3)) | (0x07 & (src[4]>>5));
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*dest++ = tab[j];
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j = (0x1f & (src[4]));
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*dest++ = tab[j];
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src += 5;
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nsrc -= 5;
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}
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if(nsrc){
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j = (0x1f & (src[0]>>3));
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*dest++ = tab[j];
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j = (0x1c & (src[0]<<2));
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if(nsrc == 1)
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goto out;
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j |= (0x03 & (src[1]>>6));
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*dest++ = tab[j];
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j = (0x1f & (src[1]>>1));
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if(nsrc == 2)
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goto out;
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*dest++ = tab[j];
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j = (0x10 & (src[1]<<4));
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if(nsrc == 3)
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goto out;
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j |= (0x0f & (src[2]>>4));
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*dest++ = tab[j];
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j = (0x1e & (src[2]<<1));
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if(nsrc == 4)
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goto out;
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j |= (0x01 & (src[3]>>7));
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*dest++ = tab[j];
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j = (0x1f & (src[3]>>2));
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*dest++ = tab[j];
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j = (0x18 & (src[3]<<3));
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out:
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*dest++ = tab[j];
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}
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*dest = 0;
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return dest-start;
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}
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