UUEncode.cpp

00001 #include "mbed.h"
00002 #include "LPC.h"
00003 
00004 //ENCODING FUNCTIONS BELOW
00005 int SerialBuffered::UUEncode() {       //Encodes the next 45 bytes in the file into a UUEncoded string with checksum and LF/CR characters ready to be sent to the board
00006     int loop=0;  int i;  checksum=0;
00007     for (int a=0; a<=63; a++) uuline[a]=0;
00008     for (i=0; i<15; i++) {
00009         if ((ch1=fgetc(f)) == EOF)  //Padded with 0x00 making life easier when the end of the file is reached
00010             ch1=0x00;
00011         if ((ch2=fgetc(f)) == EOF)
00012             ch2=0x00;
00013         if ((ch3=fgetc(f)) == EOF)
00014             ch3=0x00;
00015         checksum +=3;
00016         Encode3();
00017         uuline[1+(loop*4)]=n1;
00018         uuline[2+(loop*4)]=n2;
00019         uuline[3+(loop*4)]=n3;
00020         uuline[4+(loop*4)]=n4;
00021         loop++;
00022     }
00023     uuline[0] = checksum+32;
00024     uuline[61] = 0x0D;
00025     uuline[62] = 0x0A;
00026     uuline[63] = 0x00;
00027     return 0;
00028 }
00029 
00030 int SerialBuffered:: Encode3() {   //Does the actual raw encoding. Laid out in a less compact way to explicitly show the process going on
00031     n1 = 0, n2 = 0, n3 = 0, n4 = 0;
00032     sum20 += ch1+ch2+ch3;
00033     if ((ch1-128)>=0)   {ch1-=128;  n1+=32;}
00034     if ((ch1-64)>=0)    {ch1-=64;   n1+=16;}
00035     if ((ch1-32)>=0)    {ch1-=32;   n1+=8;}
00036     if ((ch1-16)>=0)    {ch1-=16;   n1+=4;}
00037     if ((ch1-8)>=0)     {ch1-=8;    n1+=2;}
00038     if ((ch1-4)>=0)     {ch1-=4;    n1+=1;}
00039 
00040     if ((ch1-2)>=0)     {ch1-=2;    n2+=32;}
00041     if ((ch1-1)>=0)     {ch1-=1;    n2+=16;}
00042     if ((ch2-128)>=0)   {ch2-=128;  n2+=8;}
00043     if ((ch2-64)>=0)    {ch2-=64;   n2+=4;}
00044     if ((ch2-32)>=0)    {ch2-=32;   n2+=2;}
00045     if ((ch2-16)>=0)    {ch2-=16;   n2+=1;}
00046 
00047     if ((ch2-8)>=0)     {ch2-=8;    n3+=32;}
00048     if ((ch2-4)>=0)     {ch2-=4;    n3+=16;}
00049     if ((ch2-2)>=0)     {ch2-=2;    n3+=8;}
00050     if ((ch2-1)>=0)     {ch2-=1;    n3+=4;}
00051     if ((ch3-128)>=0)   {ch3-=128;  n3+=2;}
00052     if ((ch3-64)>=0)    {ch3-=64;   n3+=1;}
00053 
00054     if ((ch3-32)>=0)    {ch3-=32;   n4+=32;}
00055     if ((ch3-16)>=0)    {ch3-=16;   n4+=16;}
00056     if ((ch3-8)>=0)     {ch3-=8;    n4+=8;}
00057     if ((ch3-4)>=0)     {ch3-=4;    n4+=4;}
00058     if ((ch3-2)>=0)     {ch3-=2;    n4+=2;}
00059     if ((ch3-1)>=0)     {ch3-=1;    n4+=1;}
00060 
00061     if (n1 == 0x00) n1=0x60;
00062     else n1+=0x20;
00063     if (n2 == 0x00) n2=0x60;
00064     else n2+=0x20;
00065     if (n3 == 0x00) n3=0x60;
00066     else n3+=0x20;
00067     if (n4 == 0x00) n4=0x60;
00068     else n4+=0x20;
00069     return 0;
00070 }
00071 
00072 int SerialBuffered::FirstEncode() {  //Function to add two's complement of the first 7 DWORDs into the space occupied by the 8th DWORD (DWORDs 1-8 should add to zero)
00073     long int precheck = 0;
00074     int a;
00075     for (a=0; a<9; a++) {
00076         ch1 = fgetc(f);  ch2 = fgetc(f);     ch3 = fgetc(f);
00077         sum[a*3]=ch1;    sum[(a*3)+1]=ch2;   sum[(a*3)+2]=ch3;
00078     }
00079     ch1 = fgetc(f);  fgetc(f);  fgetc(f);  fgetc(f);  fgetc(f);  //Ignores the 4 bytes which are to be overwritten
00080     sum[27] = ch1;
00081     
00082     for (a=0; a<7; a++) {
00083         sum1[a*4] = sum[a*4+3];
00084         sum1[a*4+1] = sum[a*4+2];
00085         sum1[a*4+2] = sum[a*4+1];
00086         sum1[a*4+3] = sum[a*4];
00087         precheck += (sum1[a*4]*0x1000000) + (sum1[a*4+1]*0x10000) + (sum1[a*4+2]*0x100) + sum1[a*4+3];
00088     }
00089     precheck = ~precheck+1;  //Takes the two's complement of the checksum
00090     sum[28] = precheck & 0xFF;
00091     sum[29] = (precheck >> 8) & 0xFF;
00092     sum[30] = (precheck >>16) & 0xFF;
00093     sum[31] = (precheck >>24) & 0xFF;
00094     sum[32] = fgetc(f);
00095     for (int a=33; a<46; a++) sum[a] = fgetc(f);
00096     fseek(f, 0, SEEK_END);
00097     filesize = ftell(f);
00098     fclose(f);
00099     f=fopen("/fs/delete.bin", "w");   //Opens a temporary file for writing to
00100     fwrite (sum, 1, sizeof(sum), f);  //Writes the checksum-added and encoded bytes
00101     fclose(f);
00102     f=fopen("/fs/delete.bin", "r");   //Opens the original binary file again for reading
00103     UUEncode();  
00104     return 0;
00105 }
00106 
00107 int SerialBuffered::EndUUEncode() {  //Encodes the last 124 bytes of a 1024 byte block
00108     int loop=0;  int i;  checksum=0;
00109     for (int a=0; a<=50; a++) enduuline[a]=0;
00110     for (i=1; i<=12; i++) {
00111         if ((ch1=fgetc(f)) == EOF)
00112             ch1=0x00;
00113         if ((ch2=fgetc(f)) == EOF)
00114             ch2=0x00;
00115         if ((ch3=fgetc(f)) == EOF)
00116             ch3=0x00;
00117         checksum +=3;
00118         if (loop==11) {
00119             checksum-=2;
00120             fseek (f, -2, SEEK_CUR);
00121             ch2=0x00; ch3=0x00;
00122         }
00123         Encode3();
00124         enduuline[1+(loop*4)]=n1;
00125         enduuline[2+(loop*4)]=n2;
00126         enduuline[3+(loop*4)]=n3;
00127         enduuline[4+(loop*4)]=n4;
00128         loop++;
00129     }
00130     enduuline[0] = checksum+32;
00131     enduuline[49] = 0x0D;
00132     enduuline[50] = 0x0A;
00133     enduuline[51] = 0x00;
00134     return 0;
00135 }