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| Commit | Line | Data |
|---|---|---|
| cf908fd1 WJ |
1 | /* real2prim.c - real to presentation element */ |
| 2 | ||
| 3 | #ifndef lint | |
| 4 | static char *rcsid = "$Header: /f/osi/psap/RCS/real2prim.c,v 7.1 91/02/22 09:36:50 mrose Interim $"; | |
| 5 | #endif | |
| 6 | ||
| 7 | /* | |
| 8 | * $Header: /f/osi/psap/RCS/real2prim.c,v 7.1 91/02/22 09:36:50 mrose Interim $ | |
| 9 | * | |
| 10 | * Contributed by Julian Onions, Nottingham University. | |
| 11 | * July 1989 - this is awful stuff! | |
| 12 | * | |
| 13 | 8 | |
| 14 | * $Log: real2prim.c,v $ | |
| 15 | * Revision 7.1 91/02/22 09:36:50 mrose | |
| 16 | * Interim 6.8 | |
| 17 | * | |
| 18 | * Revision 7.0 89/11/23 22:13:34 mrose | |
| 19 | * Release 6.0 | |
| 20 | * | |
| 21 | */ | |
| 22 | ||
| 23 | /* | |
| 24 | * NOTICE | |
| 25 | * | |
| 26 | * Acquisition, use, and distribution of this module and related | |
| 27 | * materials are subject to the restrictions of a license agreement. | |
| 28 | * Consult the Preface in the User's Manual for the full terms of | |
| 29 | * this agreement. | |
| 30 | * | |
| 31 | */ | |
| 32 | ||
| 33 | ||
| 34 | /* LINTLIBRARY */ | |
| 35 | ||
| 36 | #include "psap.h" | |
| 37 | ||
| 38 | /* \f */ | |
| 39 | ||
| 40 | PE real2prim (d, class, id) | |
| 41 | register double d; | |
| 42 | PElementClass class; | |
| 43 | PElementID id; | |
| 44 | { | |
| 45 | register PE pe; | |
| 46 | double mant, nm; | |
| 47 | int exponent; | |
| 48 | int expsign; | |
| 49 | int parts[sizeof (double)]; | |
| 50 | int sign, i, maxi, mask; | |
| 51 | int n, explen; | |
| 52 | PElementData dp; | |
| 53 | ||
| 54 | if ((pe = pe_alloc (class, PE_FORM_PRIM, id)) == NULLPE) | |
| 55 | return NULLPE; | |
| 56 | ||
| 57 | if (d == 0.0) | |
| 58 | return pe; | |
| 59 | ||
| 60 | mant = frexp (d, &exponent); | |
| 61 | ||
| 62 | if (mant < 0.0) { | |
| 63 | sign = -1; | |
| 64 | mant = -mant; | |
| 65 | } | |
| 66 | else sign = 1; | |
| 67 | ||
| 68 | nm = mant; | |
| 69 | for (i = 0; i < sizeof (double) ; i++) { | |
| 70 | int intnm; | |
| 71 | nm *= (1<<8); | |
| 72 | intnm = ((int)nm) & 0xff; | |
| 73 | nm -= intnm; | |
| 74 | if (intnm) | |
| 75 | maxi = i + 1; | |
| 76 | parts[i] = intnm; | |
| 77 | } | |
| 78 | ||
| 79 | exponent -= 8 * maxi; | |
| 80 | ||
| 81 | expsign = exponent >= 0 ? exponent : exponent ^ (-1); | |
| 82 | mask = 0x1ff << (((n = sizeof exponent) - 1) * 8 - 1); | |
| 83 | while (n > 1 && (expsign & mask) == 0) | |
| 84 | mask >>= 8, n--; | |
| 85 | ||
| 86 | explen = n; | |
| 87 | if (n > 3) | |
| 88 | n ++; | |
| 89 | ||
| 90 | if ((pe -> pe_prim = PEDalloc (n + maxi + 1)) == NULLPED) { | |
| 91 | pe_free (pe); | |
| 92 | return NULLPE; | |
| 93 | } | |
| 94 | ||
| 95 | dp = pe -> pe_prim + (pe -> pe_len = n + maxi + 1); | |
| 96 | ||
| 97 | for (; maxi > 0; maxi --) | |
| 98 | *--dp = parts[maxi - 1]; | |
| 99 | for (n = explen; n-- > 0; exponent >>= 8) | |
| 100 | *--dp = exponent & 0xff; | |
| 101 | if (explen > 3) | |
| 102 | *--dp = explen & 0xff; | |
| 103 | ||
| 104 | switch (explen) { | |
| 105 | case 1: | |
| 106 | explen = PE_REAL_B_EF1; | |
| 107 | break; | |
| 108 | case 2: | |
| 109 | explen = PE_REAL_B_EF2; | |
| 110 | break; | |
| 111 | case 3: | |
| 112 | explen = PE_REAL_B_EF3; | |
| 113 | break; | |
| 114 | default: | |
| 115 | explen = PE_REAL_B_EF3; | |
| 116 | break; | |
| 117 | } | |
| 118 | *--dp = PE_REAL_BINENC | |
| 119 | | PE_REAL_B_B2 | |
| 120 | | (sign == -1 ? PE_REAL_B_S : 0) | |
| 121 | | explen; | |
| 122 | return pe; | |
| 123 | } | |
| 124 | ||
| 125 | ||
| 126 | ||
| 127 |