| 1 | |
| 2 | #include <stdio.h> |
| 3 | #include "structures.h" |
| 4 | #include "ops.h" |
| 5 | |
| 6 | /* |
| 7 | * Pack an OS/8 filename into 6 bit code, 2 digits per 12 bit word. |
| 8 | * Argument is a zero-terminated string, containing the full name with |
| 9 | * the dot, i.E. "XXXXXX.YY",0 is the legal form. |
| 10 | */ |
| 11 | void os8_file_name_pack(os8_file_name_t * filename, char * data){ |
| 12 | |
| 13 | /* Read and write positions */ |
| 14 | int inpos=0, outpos=0; |
| 15 | |
| 16 | /* Zero out all data in target */ |
| 17 | for (outpos=0; outpos<4; outpos++) filename->data[outpos]=0; |
| 18 | |
| 19 | for (outpos=0; outpos<8 && data[inpos];){ |
| 20 | if (data[inpos]=='.'){ |
| 21 | inpos++; |
| 22 | if (outpos<6) outpos=6; |
| 23 | continue; |
| 24 | } |
| 25 | filename->data[outpos/2] |= os8_ascii2pdp(data[inpos++]) << ((!(outpos%2))*6); |
| 26 | outpos++; |
| 27 | } |
| 28 | } |
| 29 | |
| 30 | void os8_file_name_extract(os8_file_name_t * filename, char * data){ |
| 31 | |
| 32 | /* Read and write positions */ |
| 33 | int inpos=0, outpos=0; |
| 34 | |
| 35 | for (inpos=0; inpos<8; inpos++){ |
| 36 | |
| 37 | unsigned short int current=filename->data[inpos/2]; /* Get right word */ |
| 38 | if (!(inpos%2)) current >>= 6; |
| 39 | current &= 077; |
| 40 | |
| 41 | if ((!current) && ((inpos==0)||(inpos==6))){ /* Empty file name or extension*/ |
| 42 | data[outpos]=0; /* Terminate file name in buffer */ |
| 43 | break; /* Leave the loop! */ |
| 44 | } |
| 45 | |
| 46 | if (inpos==6){ |
| 47 | data[outpos++]='.'; /* Insert dot into new name */ |
| 48 | } |
| 49 | |
| 50 | if (current) { /* Insert character into output */ |
| 51 | data[outpos++]=os8_pdp2ascii(current); |
| 52 | } |
| 53 | } |
| 54 | data[outpos]=0; /* Terminate string. */ |
| 55 | } |
| 56 | |
| 57 | /* Pack one character into 6 bit OS/8 reduced ASCII code */ |
| 58 | unsigned char os8_ascii2pdp(unsigned char inchar){ |
| 59 | unsigned char result=inchar & 077; /* Strip upper bits */ |
| 60 | return result; |
| 61 | } |
| 62 | |
| 63 | /* Extract one character from 6 bit OS/8 reduced ASCII code */ |
| 64 | unsigned char os8_pdp2ascii(unsigned char inchar){ |
| 65 | inchar &=077; |
| 66 | if (inchar<040) return inchar|0100; |
| 67 | return inchar; |
| 68 | } |
| 69 | |
| 70 | /* Negate a p8word */ |
| 71 | p8word p8_neg(p8word in){ |
| 72 | return (-in)&07777; |
| 73 | } |
| 74 | |
| 75 | /* Twist the bytes for little endian machines */ |
| 76 | p8word p8_twist(p8word in){ |
| 77 | return (in&0xff)<<8 | ((in>>8)&0xff); |
| 78 | } |
| 79 | |
| 80 | |
| 81 | |
| 82 | |
| 83 | |
| 84 | |