| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Simple scalar fields |
| 4 | * |
| 5 | * (c) 2017 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 9 | * |
| 10 | * This file is part of Catacomb. |
| 11 | * |
| 12 | * Catacomb is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU Library General Public License as |
| 14 | * published by the Free Software Foundation; either version 2 of the |
| 15 | * License, or (at your option) any later version. |
| 16 | * |
| 17 | * Catacomb is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | * GNU Library General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU Library General Public |
| 23 | * License along with Catacomb; if not, write to the Free |
| 24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 25 | * MA 02111-1307, USA. |
| 26 | */ |
| 27 | |
| 28 | #ifndef CATACOMB_SCAF_H |
| 29 | #define CATACOMB_SCAF_H |
| 30 | |
| 31 | #ifdef __cplusplus |
| 32 | extern "C" { |
| 33 | #endif |
| 34 | |
| 35 | /*----- Header files ------------------------------------------------------*/ |
| 36 | |
| 37 | #include <mLib/bits.h> |
| 38 | |
| 39 | /*----- Type selection ----------------------------------------------------*/ |
| 40 | |
| 41 | #ifndef SCAF_IMPL |
| 42 | # ifdef HAVE_UINT64 |
| 43 | # define SCAF_IMPL 32 |
| 44 | # else |
| 45 | # define SCAF_IMPL 16 |
| 46 | # endif |
| 47 | #endif |
| 48 | |
| 49 | #if SCAF_IMPL == 32 |
| 50 | typedef uint32 scaf_piece; |
| 51 | typedef uint64 scaf_dblpiece; |
| 52 | #endif |
| 53 | #if SCAF_IMPL == 16 |
| 54 | typedef uint16 scaf_piece; |
| 55 | typedef uint32 scaf_dblpiece; |
| 56 | #endif |
| 57 | |
| 58 | #define SCAF_NPIECE(bits, piecewd) (((bits) + piecewd - 1)/piecewd) |
| 59 | |
| 60 | /*----- Functions provided -----------------------------------------------*/ |
| 61 | |
| 62 | /* --- @scaf_load@ --- * |
| 63 | * |
| 64 | * Arguments: @scaf_piece *z@ = where to write the result |
| 65 | * @const octet *b@ = source buffer to read |
| 66 | * @size_t sz@ = size of the source buffer |
| 67 | * @size_t npiece@ = number of pieces to read |
| 68 | * @unsigned piecewd@ = nominal width of pieces in bits |
| 69 | * |
| 70 | * Returns: --- |
| 71 | * |
| 72 | * Use: Loads a little-endian encoded scalar into a vector @z@ of |
| 73 | * single-precision pieces. |
| 74 | */ |
| 75 | |
| 76 | extern void scaf_load(scaf_piece */*z*/, const octet */*b*/, size_t /*sz*/, |
| 77 | size_t /*npiece*/, unsigned /*piecewd*/); |
| 78 | |
| 79 | /* --- @scaf_loaddbl@ --- * |
| 80 | * |
| 81 | * Arguments: @scaf_dblpiece *z@ = where to write the result |
| 82 | * @const octet *b@ = source buffer to read |
| 83 | * @size_t sz@ = size of the source buffer |
| 84 | * @size_t npiece@ = number of pieces to read |
| 85 | * @unsigned piecewd@ = nominal width of pieces in bits |
| 86 | * |
| 87 | * Returns: --- |
| 88 | * |
| 89 | * Use: Loads a little-endian encoded scalar into a vector @z@ of |
| 90 | * double-precision pieces. |
| 91 | */ |
| 92 | |
| 93 | extern void scaf_loaddbl(scaf_dblpiece */*z*/, const octet */*b*/, |
| 94 | size_t /*sz*/, size_t /*npiece*/, |
| 95 | unsigned /*piecewd*/); |
| 96 | |
| 97 | /* --- @scaf_store@ --- * |
| 98 | * |
| 99 | * Arguments: @octet *b@ = buffer to fill in |
| 100 | * @size_t sz@ = size of the buffer |
| 101 | * @const scaf_piece *x@ = scalar to store |
| 102 | * @size_t npiece@ = number of pieces in @x@ |
| 103 | * @unsigned piecewd@ = nominal width of pieces in bits |
| 104 | * |
| 105 | * Returns: --- |
| 106 | * |
| 107 | * Use: Stores a scalar in a vector of single-precison pieces as a |
| 108 | * little-endian vector of bytes. |
| 109 | */ |
| 110 | |
| 111 | extern void scaf_store(octet */*b*/, size_t /*sz*/, const scaf_piece */*x*/, |
| 112 | size_t /*npiece*/, unsigned /*piecewd*/); |
| 113 | |
| 114 | /* --- @scaf_mul@ --- * |
| 115 | * |
| 116 | * Arguments: @scaf_dblpiece *z@ = where to put the answer |
| 117 | * @const scaf_piece *x, *y@ = the operands |
| 118 | * @size_t npiece@ = the length of the operands |
| 119 | * |
| 120 | * Returns: --- |
| 121 | * |
| 122 | * Use: Multiply two scalars. The destination must have space for |
| 123 | * @2*npiece@ pieces (though the last one will always be zero). |
| 124 | * The result is not reduced. |
| 125 | */ |
| 126 | |
| 127 | extern void scaf_mul(scaf_dblpiece */*z*/, const scaf_piece */*x*/, |
| 128 | const scaf_piece */*y*/, size_t /*npiece*/); |
| 129 | |
| 130 | /* --- @scaf_reduce@ --- * |
| 131 | * |
| 132 | * Arguments: @scaf_piece *z@ = where to write the result |
| 133 | * @const scaf_dblpiece *x@ = the operand to reduce |
| 134 | * @const scaf_piece *l@ = the modulus, in internal format |
| 135 | * @const scaf_piece *mu@ = scaled approximation to @1/l@ |
| 136 | * @size_t npiece@ = number of pieces in @l@ |
| 137 | * @unsigned piecewd@ = nominal width of a piece in bits |
| 138 | * @scaf_piece *scratch@ = @3*npiece + 1@ scratch pieces |
| 139 | * |
| 140 | * Returns: --- |
| 141 | * |
| 142 | * Use: Reduce @x@ (a vector of @2*npiece@ double-precision pieces) |
| 143 | * modulo @l@ (a vector of @npiece@ single-precision pieces), |
| 144 | * writing the result to @z@. |
| 145 | * |
| 146 | * Write @n = npiece@, @w = piecewd@, and %$B = 2^w$%. The |
| 147 | * operand @mu@ must contain %$\lfloor B^{2n}/l \rfloor$%, in |
| 148 | * @npiece + 1@ pieces. Furthermore, we must have |
| 149 | * %$3 l < B^n$%. (Fiddle with %$w$% if necessary.) |
| 150 | */ |
| 151 | |
| 152 | extern void scaf_reduce(scaf_piece */*z*/, const scaf_dblpiece */*x*/, |
| 153 | const scaf_piece */*l*/, const scaf_piece */*mu*/, |
| 154 | size_t /*npiece*/, unsigned /*piecewd*/, |
| 155 | scaf_piece */*scratch*/); |
| 156 | |
| 157 | /*----- That's all, folks -------------------------------------------------*/ |
| 158 | |
| 159 | #ifdef __cplusplus |
| 160 | } |
| 161 | #endif |
| 162 | |
| 163 | #endif |