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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: gfreduce.h,v 1.3 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
5 | * Reduction modulo sparse binary polynomials |
6 | * |
7 | * (c) 2004 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
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30 | #ifndef CATACOMB_GFREDUCE_H |
31 | #define CATACOMB_GFREDUCE_H |
32 | |
33 | #ifdef __cplusplus |
34 | extern "C" { |
35 | #endif |
36 | |
37 | /*----- Header files ------------------------------------------------------*/ |
38 | |
39 | #ifndef CATACOMB_GF_H |
40 | # include "gf.h" |
41 | #endif |
42 | |
43 | /*----- Data structures ---------------------------------------------------*/ |
44 | |
45 | typedef struct gfreduce_instr { |
46 | unsigned op; /* Instruction opcode */ |
47 | size_t arg; /* Immediate argument */ |
48 | } gfreduce_instr; |
49 | |
50 | enum { |
51 | GFRI_LOAD, /* Load @p[arg]@ */ |
52 | GFRI_LSL, /* XOR with @w << arg@ */ |
53 | GFRI_LSR, /* XOR with @w >> arg@ */ |
54 | GFRI_STORE, /* Store @p[arg]@ */ |
55 | GFRI_MAX |
56 | }; |
57 | |
58 | typedef struct gfreduce { |
59 | size_t lim; /* Word of degree bit */ |
60 | mpw mask; /* Mask for degree word */ |
61 | mp *p; /* Copy of the polynomial */ |
62 | size_t in; /* Number of instruction words */ |
63 | gfreduce_instr *iv, *liv; /* Vector of instructions */ |
64 | } gfreduce; |
65 | |
66 | /*----- Functions provided ------------------------------------------------*/ |
67 | |
68 | /* --- @gfreduce_create@ --- * |
69 | * |
70 | * Arguments: @gfreduce *r@ = structure to fill in |
71 | * @mp *x@ = a (hopefully sparse) polynomial |
72 | * |
73 | * Returns: --- |
74 | * |
75 | * Use: Initializes a context structure for reduction. |
76 | */ |
77 | |
78 | extern void gfreduce_create(gfreduce */*r*/, mp */*p*/); |
79 | |
80 | /* --- @gfreduce_destroy@ --- * |
81 | * |
82 | * Arguments: @gfreduce *r@ = structure to free |
83 | * |
84 | * Returns: --- |
85 | * |
86 | * Use: Reclaims the resources from a reduction context. |
87 | */ |
88 | |
89 | extern void gfreduce_destroy(gfreduce */*r*/); |
90 | |
91 | /* --- @gfreduce_dump@ --- * |
92 | * |
93 | * Arguments: @gfreduce *r@ = structure to dump |
94 | * @FILE *fp@ = file to dump on |
95 | * |
96 | * Returns: --- |
97 | * |
98 | * Use: Dumps a reduction context. |
99 | */ |
100 | |
101 | extern void gfreduce_dump(gfreduce */*r*/, FILE */*fp*/); |
102 | |
103 | /* --- @gfreduce_do@ --- * |
104 | * |
105 | * Arguments: @gfreduce *r@ = reduction context |
106 | * @mp *d@ = destination |
107 | * @mp *x@ = source |
108 | * |
109 | * Returns: Destination, @x@ reduced modulo the reduction poly. |
110 | */ |
111 | |
112 | extern mp *gfreduce_do(gfreduce */*r*/, mp */*d*/, mp */*x*/); |
113 | |
114 | /* --- @gfreduce_sqrt@ --- * |
115 | * |
116 | * Arguments: @gfreduce *r@ = pointer to reduction context |
117 | * @mp *d@ = destination |
118 | * @mp *x@ = some polynomial |
119 | * |
120 | * Returns: The square root of @x@ modulo @r->p@, or null. |
121 | */ |
122 | |
123 | extern mp *gfreduce_sqrt(gfreduce */*r*/, mp */*d*/, mp */*x*/); |
124 | |
125 | /* --- @gfreduce_trace@ --- * |
126 | * |
127 | * Arguments: @gfreduce *r@ = pointer to reduction context |
128 | * @mp *x@ = some polynomial |
129 | * |
130 | * Returns: The trace of @x@. (%$\Tr(x)=x + x^2 + \cdots + x^{2^{m-1}}$% |
131 | * if %$x \in \gf{2^m}$%). |
132 | */ |
133 | |
134 | extern int gfreduce_trace(gfreduce */*r*/, mp */*x*/); |
135 | |
136 | /* --- @gfreduce_halftrace@ --- * |
137 | * |
138 | * Arguments: @gfreduce *r@ = pointer to reduction context |
139 | * @mp *d@ = destination |
140 | * @mp *x@ = some polynomial |
141 | * |
142 | * Returns: The half-trace of @x@. |
143 | * (%$\HfTr(x)= x + x^{2^2} + \cdots + x^{2^{m-1}}$% |
144 | * if %$x \in \gf{2^m}$% with %$m$% odd). |
145 | */ |
146 | |
147 | extern mp *gfreduce_halftrace(gfreduce */*r*/, mp */*d*/, mp */*x*/); |
148 | |
149 | /* --- @gfreduce_quadsolve@ --- * |
150 | * |
151 | * Arguments: @gfreduce *r@ = pointer to reduction context |
152 | * @mp *d@ = destination |
153 | * @mp *x@ = some polynomial |
154 | * |
155 | * Returns: A polynomial @y@ such that %$y^2 + y = x$%, or null. |
156 | */ |
157 | |
158 | extern mp *gfreduce_quadsolve(gfreduce */*r*/, mp */*d*/, mp */*x*/); |
159 | |
160 | /* --- @gfreduce_exp@ --- * |
161 | * |
162 | * Arguments: @gfreduce *gr@ = pointer to reduction context |
163 | * @mp *d@ = fake destination |
164 | * @mp *a@ = base |
165 | * @mp *e@ = exponent |
166 | * |
167 | * Returns: Result, %$a^e \bmod m$%. |
168 | */ |
169 | |
170 | extern mp *gfreduce_exp(gfreduce */*gr*/, mp */*d*/, mp */*a*/, mp */*e*/); |
171 | |
172 | /*----- That's all, folks -------------------------------------------------*/ |
173 | |
174 | #ifdef __cplusplus |
175 | } |
176 | #endif |
177 | |
178 | #endif |