projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 0bdacbe1 AM |
1 | /* File : int2str.c |
| 2 | Author : Richard A. O'Keefe | |
| 3 | Updated: 6 February 1993 | |
| 4 | Defines: int2str() | |
| 5 | ||
| 6 | int2str(dst, radix, val) | |
| 7 | converts the (long) integer "val" to character form and moves it to | |
| 8 | the destination string "dst" followed by a terminating NUL. The | |
| 9 | result is normally a pointer to this NUL character, but if the radix | |
| 10 | is dud the result will be NullS and nothing will be changed. | |
| 11 | ||
| 12 | If radix is -2..-36, val is taken to be SIGNED. | |
| 13 | If radix is 2.. 36, val is taken to be UNSIGNED. | |
| 14 | That is, val is signed if and only if radix is. You will normally | |
| 15 | use radix -10 only through itoa and ltoa, for radix 2, 8, or 16 | |
| 16 | unsigned is what you generally want. | |
| 17 | */ | |
| 18 | ||
| 19 | static char dig_vec[] = | |
| 20 | "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; | |
| 21 | ||
| 22 | ||
| 23 | char *int2str(dst, radix, val) | |
| 24 | register char *dst; | |
| 25 | register int radix; | |
| 26 | register long val; | |
| 27 | { | |
| 28 | char buffer[65]; /* Ready for 64-bit machines */ | |
| 29 | register char *p; | |
| 30 | ||
| 31 | if (radix < 2 || radix > 36) { /* Not 2..36 */ | |
| 32 | if (radix > -2 || radix < -36) return (char *)0; | |
| 33 | if (val < 0) { | |
| 34 | *dst++ = '-'; | |
| 35 | val = -val; | |
| 36 | } | |
| 37 | radix = -radix; | |
| 38 | } | |
| 39 | /* The slightly contorted code which follows is due to the | |
| 40 | fact that few machines directly support unsigned long / and %. | |
| 41 | Certainly the VAX C compiler generates a subroutine call. In | |
| 42 | the interests of efficiency (hollow laugh) I let this happen | |
| 43 | for the first digit only; after that "val" will be in range so | |
| 44 | that signed integer division will do. Sorry 'bout that. | |
| 45 | CHECK THE CODE PRODUCED BY YOUR C COMPILER. The first % and / | |
| 46 | should be unsigned, the second % and / signed, but C compilers | |
| 47 | tend to be extraordinarily sensitive to minor details of style. | |
| 48 | This works on a VAX, that's all I claim for it. | |
| 49 | */ | |
| 50 | p = &buffer[sizeof buffer]; | |
| 51 | *--p = '\0'; | |
| 52 | *--p = dig_vec[(unsigned long)val%(unsigned long)radix]; | |
| 53 | val = (unsigned long)val/(unsigned long)radix; | |
| 54 | while (val != 0) *--p = dig_vec[val%radix], val /= radix; | |
| 55 | while (*dst++ = *p++) ; | |
| 56 | return dst-1; | |
| 57 | } | |
| 58 |