ref: d0ab3a0dd8f6355b3603d0fb04043a9ae867639b
dir: /libkern/u32.c/
#include <lib9.h> int dec32(uchar *dest, int ndest, char *src, int nsrc) { char *s, *tab; uchar *start; int i, u[8]; if(ndest+1 < (5*nsrc+7)/8) return -1; start = dest; tab = "23456789abcdefghijkmnpqrstuvwxyz"; while(nsrc>=8){ for(i=0; i<8; i++){ s = strchr(tab,(int)src[i]); u[i] = s ? s-tab : 0; } *dest++ = (u[0]<<3) | (0x7 & (u[1]>>2)); *dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4)); *dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1)); *dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3)); *dest++ = ((0x7 & u[6])<<5) | u[7]; src += 8; nsrc -= 8; } if(nsrc > 0){ if(nsrc == 1 || nsrc == 3 || nsrc == 6) return -1; for(i=0; i<nsrc; i++){ s = strchr(tab,(int)src[i]); u[i] = s ? s-tab : 0; } *dest++ = (u[0]<<3) | (0x7 & (u[1]>>2)); if(nsrc == 2) goto out; *dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4)); if(nsrc == 4) goto out; *dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1)); if(nsrc == 5) goto out; *dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3)); } out: return dest-start; } int enc32(char *dest, int ndest, uchar *src, int nsrc) { char *tab, *start; int j; if(ndest <= (8*nsrc+4)/5 ) return -1; start = dest; tab = "23456789abcdefghijkmnpqrstuvwxyz"; while(nsrc>=5){ j = (0x1f & (src[0]>>3)); *dest++ = tab[j]; j = (0x1c & (src[0]<<2)) | (0x03 & (src[1]>>6)); *dest++ = tab[j]; j = (0x1f & (src[1]>>1)); *dest++ = tab[j]; j = (0x10 & (src[1]<<4)) | (0x0f & (src[2]>>4)); *dest++ = tab[j]; j = (0x1e & (src[2]<<1)) | (0x01 & (src[3]>>7)); *dest++ = tab[j]; j = (0x1f & (src[3]>>2)); *dest++ = tab[j]; j = (0x18 & (src[3]<<3)) | (0x07 & (src[4]>>5)); *dest++ = tab[j]; j = (0x1f & (src[4])); *dest++ = tab[j]; src += 5; nsrc -= 5; } if(nsrc){ j = (0x1f & (src[0]>>3)); *dest++ = tab[j]; j = (0x1c & (src[0]<<2)); if(nsrc == 1) goto out; j |= (0x03 & (src[1]>>6)); *dest++ = tab[j]; j = (0x1f & (src[1]>>1)); if(nsrc == 2) goto out; *dest++ = tab[j]; j = (0x10 & (src[1]<<4)); if(nsrc == 3) goto out; j |= (0x0f & (src[2]>>4)); *dest++ = tab[j]; j = (0x1e & (src[2]<<1)); if(nsrc == 4) goto out; j |= (0x01 & (src[3]>>7)); *dest++ = tab[j]; j = (0x1f & (src[3]>>2)); *dest++ = tab[j]; j = (0x18 & (src[3]<<3)); out: *dest++ = tab[j]; } *dest = 0; return dest-start; }