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darius.briquet
reed_solomon
Commits
e5d42cb2
Commit
e5d42cb2
authored
3 years ago
by
nicolas.albanesi
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Added comments to the functions
parent
5dad04d5
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5
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5 changed files
euclide.py
+15
-8
15 additions, 8 deletions
euclide.py
inverse_mult.py
+10
-3
10 additions, 3 deletions
inverse_mult.py
main.py
+1
-6
1 addition, 6 deletions
main.py
polynome.py
+1
-1
1 addition, 1 deletion
polynome.py
reed_solomon.py
+62
-2
62 additions, 2 deletions
reed_solomon.py
with
89 additions
and
20 deletions
euclide.py
+
15
−
8
View file @
e5d42cb2
'''
Description : Calcule le PGCD de deux nombres et leurs
coefficients de bezout
Return : PGCD, Coef de X, Coef de Y
(X est le nombre le plus grand)
'''
def
pgcd_etendu
(
a
,
b
):
'''
Calcule le PGCD de deux nombres et leurs
coefficients de bezout
Args:
a (int): Nombre a
b (int): Nombre b
Returns:
[int]: PGCD
[int]: Coefficient X
[int]: Coefficient Y
'''
a
,
b
=
abs
(
a
),
abs
(
b
)
# On s'assure que le plus grand nombre est a
if
b
>
a
:
...
...
@@ -50,6 +57,6 @@ if __name__ == '__main__':
a
=
4991
b
=
1197
print
(
pgcd_etendu
(
a
,
b
))
print
(
pgcd_etendu
(
b
,
a
))
pgcd
,
x
,
y
=
pgcd_etendu
(
a
,
b
)
print
(
pgcd_etendu_verif
(
a
,
b
,
x
,
y
,
pgcd
))
\ No newline at end of file
# print(pgcd_etendu_verif(a, b, x, y, pgcd))
\ No newline at end of file
This diff is collapsed.
Click to expand it.
inverse_mult.py
+
10
−
3
View file @
e5d42cb2
...
...
@@ -3,10 +3,17 @@
from
euclide
import
*
# Get the multiplicvative inverse of a Mod p
# x = Multiplicative inverse of a mod p:
# a * x mod p = 1
def
inverse_mult
(
a
,
p
)
:
"""
Calcule l
'
inverse multiplicatif de a mod p
Args:
a (int): a
p (int): Modulo p
Returns:
[int]: Inverse Modulaire
"""
pgcd
,
x
,
y
=
pgcd_etendu
(
a
,
p
)
if
pgcd
!=
1
:
return
None
...
...
This diff is collapsed.
Click to expand it.
main.py
+
1
−
6
View file @
e5d42cb2
...
...
@@ -3,13 +3,7 @@
from
polynome
import
*
from
reed_solomon
import
*
def
correct_list
(
len_list
:
int
,
p
:
polynome
):
corrected
=
[]
for
x
in
range
(
len_list
):
corrected
.
append
(
p
.
evaluate
(
x
))
return
corrected
if
__name__
==
"
__main__
"
:
...
...
@@ -26,6 +20,7 @@ if __name__ == "__main__":
l_ok
=
correct_list
(
len
(
l
),
reed_solomon
)
# Print les messages
print
(
"
Message recu :
"
+
""
.
join
(
map
(
chr
,
l
[:
MSG_LEN
])))
print
(
"
Message décodé :
"
+
""
.
join
(
map
(
chr
,
l_ok
[:
MSG_LEN
])))
...
...
This diff is collapsed.
Click to expand it.
polynome.py
+
1
−
1
View file @
e5d42cb2
...
...
@@ -42,7 +42,7 @@ class polynome():
return
polynome
(
coeff_poly_res
)
def
evaluate
(
self
,
x
):
# U
sing horner method
# U
tilise la méthode de Horner
res
=
0
for
i
in
range
(
len
(
self
.
coefs
)
-
1
,
-
1
,
-
1
):
res
=
(
res
*
x
+
self
.
coefs
[
i
])
...
...
This diff is collapsed.
Click to expand it.
reed_solomon.py
+
62
−
2
View file @
e5d42cb2
...
...
@@ -11,6 +11,15 @@ ERROR_MAX = 9
def
get_possibilities
(
l_og
:
list
,
index
:
int
):
'''
Génère une liste qui contient des listes de points
Args:
l_og (list): liste de tous les points
index (int): index à partir duquel les points sont forcément juste
Returns:
[list]: Liste de toutes les possibilitées de points
'''
l
=
l_og
.
copy
()
# Transforme the list in list of tupples with their indexes
for
x
,
_
in
enumerate
(
l
):
...
...
@@ -28,6 +37,16 @@ def get_possibilities(l_og: list, index: int):
return
p
def
lagrange_compute
(
l
:
list
)
->
polynome
:
'''
Retourne le polynome de Lagrange pour une
liste de points données
Args:
l (list): La liste de points
Returns:
polynome: Le polynome de Lagrange correspondant
'''
poly_l
=
[
0
]
*
len
(
l
)
poly
=
polynome
(
poly_l
)
for
x_i
,
y_i
in
enumerate
(
l
):
...
...
@@ -40,8 +59,18 @@ def lagrange_compute(l: list) -> polynome:
poly
=
poly
.
add
(
poly_n
)
return
poly
def
check_nb_error
(
l
:
list
,
p
:
polynome
)
->
int
:
'''
Compte le nombre d
'
erreure entre le polynome et les points de la liste
Args:
l (list): La liste de points à tester
p (polynome): Le polynome avec lequel tester la liste
Returns:
int: [description]
'''
nbr_error
=
0
for
counter
,
item
in
enumerate
(
l
):
if
(
item
%
p
.
prime_mod
)
!=
(
p
.
evaluate
(
counter
)
%
p
.
prime_mod
):
...
...
@@ -50,9 +79,40 @@ def check_nb_error(l: list, p: polynome) -> int:
def
reed_decode
(
l
:
list
)
->
polynome
:
'''
Teste toutes les listes de points et retourne le polynome de lagrange
lorsque la liste à moins de 9 erreurs
Args:
l (list): Liste de liste de points
Returns:
polynome: Polynome de Lagrange
'''
for
points
in
get_possibilities
(
l
,
INDEX_MAX
):
err
=
check_nb_error
(
l
,
lagrange_compute
(
points
))
if
((
err
)
<=
ERROR_MAX
):
# ? Chercher un polynome avec moins de 9 erreurs ?
# Possibilité d'optimiser en evitant de compute 2 fois le poly
return
lagrange_compute
(
points
)
\ No newline at end of file
return
lagrange_compute
(
points
)
def
correct_list
(
len_list
:
int
,
p
:
polynome
)
->
list
:
'''
Corrige la liste reçue en utilisant le bon polynome de Lagrange
Args:
len_list (int): Liste avec des erreurs
p (polynome): Le bon polynome de Lagrange
Returns:
list: La liste corrigée
'''
corrected
=
[]
for
x
in
range
(
len_list
):
corrected
.
append
(
p
.
evaluate
(
x
))
return
corrected
\ No newline at end of file
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