diff options
Diffstat (limited to 'b.c')
| -rw-r--r-- | b.c | 83 |
1 files changed, 83 insertions, 0 deletions
@@ -0,0 +1,83 @@ +#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+int char_index(int c){
+ if(c <= 25) return 65 + c;
+ if(c <= 51) return 71 + c;
+ if(c <= 61) return (c - 52)+48;
+ if(c == 62) return 43;
+ if(c == 63) return 47;
+ return 61;
+}
+
+int ichar_index(int c){
+ if(65 <= c && c <= 90) return c - 65;
+ if(97 <= c && c <= 122) return c - 97 + 26;
+ if(48 <= c && c <= 57) return c - 48 + 52;
+ if(c == 47) return 63;
+ return 0;
+}
+
+int de_base64(char* in, char* out){
+ int len = 0;
+ for(int i = 0; in[i]!='\0'; i++) len++;
+
+ //char out[len];
+ for(int i = 0; i < len; i+=4){
+ uint8_t u1 = i>len?0:in[i];
+ uint8_t u2 = i+1>len?0:in[i+1];
+ uint8_t u3 = i+2>len?0:in[i+2];
+ uint8_t u4 = i+3>len?0:in[i+3];
+
+ u1 = ichar_index(u1);
+ u2 = ichar_index(u2);
+ u3 = ichar_index(u3);
+ u4 = ichar_index(u4);
+
+ uint8_t left = u1 << 2 | u2 >> 4;
+ uint8_t middle = u2 << 4 | u3 >> 2;
+ uint8_t right = u3 << 6 | u4;
+
+ if(u4==0) sprintf(out,"%s%c%c",out,left,middle);
+ else if(u3==0) sprintf(out,"%s%c",out,left);
+ else sprintf(out,"%s%c%c%c",out,left,middle,right);
+
+ }
+ return 0;
+}
+int en_base64(char* in, char* out){
+ int len = 0;
+ for(int i = 0; in[i]!='\0'; i++) len++;
+
+ //char out[(len+1)*3];
+ for(int i = 0; i < len; i+=3){
+ uint8_t f = i>len?0:in[i];
+ uint8_t s = i+1>len?0:in[i+1];
+ uint8_t t = i+2>len?0:in[i+2];
+
+ uint8_t i1 = f>>2;
+ uint8_t i2 = (uint8_t)(f<<6)>>2 | (s>>4);
+ uint8_t i3 = (uint8_t)(s<<4)>>2 | (t>>6);
+ uint8_t i4 = t & 0x3f;
+
+ if(t==0)i4 = 64;
+ if(s==0)i3 = 64;
+ sprintf(out,"%s%c%c%c%c",out,char_index(i1),char_index(i2),
+ char_index(i3),char_index(i4));
+ }
+ return 0;
+}
+
+int main(){
+ char* uwu = "Many hands make light work.AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
+ char uwue[20*8000];
+ char uwud[20*8000];
+
+ en_base64(uwu, uwue);
+ de_base64(uwue, uwud);
+
+ printf("%s\n%s\n%s",uwu,uwue,uwud);
+}
+
+
|