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# TP1 : Mémoire
> Dans le répertoire [scripts](./src/scripts), vous avez 2 scripts qui permettent de formater sur la sortie standard les
> interfaces `/proc/pid/maps` et `/proc/pid/smaps` d'un processus quelconque.
#### Ex1
Compilez avec `g++` le programme [alignement.c](./src/alignement.c), et
exécutez. Vérifiez qie la taille et l'alignement de chaque structure est bien
conforme aux règles vues en cours.
#### Ex2
Soit le [programme](./src/adresses_virtuelles.c) suivant qui affiche les
adresses virtuelles de certaines variables lors de l'exécution du processus
correspondant :
```c
/* adresses virtuelles d'un processus */
#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
#include<stdlib.h>
int t[1000] = {[0 ... 999] = 2};
int main(int argc, char * argv[])
{
int i=3;
static int j = 3;
char * m = (char*)malloc(1);
printf("je suis le pid %d\n\n",getpid());
/* ------- Affichage des adresses --------*/
printf("main\t=\t%p\n",main);
printf("&argc\t=\t%p\n",&argc);
printf("&i\t=\t%p\n",&i);
printf("&j\t=\t%p\n",&j);
printf("t\t=\t%p\n",t);
printf("m\t=\t%p\n",m);
getchar();
}
```
En utilisant le (pseudo) fichier `/proc/pid/maps`, vérifiez à quel segment de
pages ces adresses appartiennent. Vous pouvez utiliser le script python
[vmap.py](./src/scripts/vmap.py).
#### Ex3
L'interface (pseudo-fichier) `proc/pid/smaps` montre la consommation mémoire
d'un processus. On peut le formater avec la commande `pmap -X` ou avec le script
python [parse_smaps.py](./src/scripts/parse_smaps.py). Le but de l'exercice est
de voir ce qui se passe au niveau de la mémoire d'un processus suivant les
différents mode d'allocation. Le programme `null.c` permet d'avoir un point de
comparaison. Vérifiez la consommation mémoire dans les cas suivants :
1. Allocation statique [buf.c](./src/ex3/buf.c).
2. Allocation sur la pile [stack.c](./src/ex3/stack.c),
3. Allocation sur le tas [heap.c](./src/ex3/heap.c),
4. Allocation (grande quantité) sur le tas [huge.c](./src/ex3/huge.c).
5. Allocation par mapping [mmap.c](./src/ex3/mmap.c).
#### Ex4
Soit le [programme](./src/bss_data.c) suivant :
```c
/* segment bss et data */
#define N 10000
int t[N]; /* version 1 */
//int t[N]={1}; /* version 2 */
int main()
{
return 0;
}
```
1. Compilez le programme. Avec la commande `size`, regardez les différents segments du programme. Où se trouve le tableau `t` ? Augmentez la valeur de N. La taille de l'exécutable a-t-elle changé ? pourquoi ?
2. Recommencez avec la version 2. Expliquez.
#### Ex5
Soit le [programme](./src/ij_ji.c) suivant :
```c
/* accès mémoire */
#include<stdio.h>
#include<time.h>
#include <stdlib.h>
#define N 8192
int t[N][N];
static inline double tstamp(void)
{
struct timespec tv;
clock_gettime(CLOCK_REALTIME, &tv);
return tv.tv_sec + tv.tv_nsec * 1.0e-9;
}
int main()
{
int i,j;
double t1,t2;
t1=tstamp();
/* version 1 */ for(i=0;i<N;i++) for(j=0;j<N;j++) t[i][j] = 1;
/* version 2 */ // for(i=0;i<N;i++) for(j=0;j<N;j++) t[j][i] = 1;
t2=tstamp();
printf("time = %lf\n",t2-t1);
return 0;
}
```
Le temps d'exécution est-il différent pour les deux versions ? Pourquoi ?
#### Ex6
Le programme [sum_array.c](./src/sum_array.c) calcule la somme des éléments
d'un tableau en accédant aux éléments séquentiellement (`-c` croissant, `-d`
décroissant) ou de manière aléatoire (`-a`) Testez en faisant varier la taille
du tableau. Expliquez .
#### Ex7
On veut implanter un allocateur de mémoire très simple. Un bloc de 8Mo est
reservé à l'aide de la fonction `mmap`. On utilise pour la gestion des demandes
d'allocation la structure suivante :
```c
struct my_memory_buffer {
char* buffer;
size_t pos;
size_t size;
};
```
- `buffer` est l'adresse de la zone reservée par `mmap`.
- `size` est la taille du buffer.
- `pos` permet de garder la trace de ce qui a déjà été alloué.
```
buffer +-------------->+---------------------------+
|###########################| \
|###########################| |
|###########################| | already allocated
|###########################| |
|###########################| |
|###########################| /
pos +-------------->----------------------------+
| | \
| | |
| | |
| | |
| | |
| | | free space
| | |
| | |
| | |
| | |
| | |
| | /
+---------------------------+
```
C'est la fonction
```c
void * my_alloc(size_t sz)
```
qui s'occupe de renvoyer l'adresse d'un bloc libre. On ne se préoccupe pas de désallocation, ni d'alignement. Une allocation consiste simplement à incrémenter (si c'est possible)
la valeur de `pos`, et à retourner l'adresse du bloc alloué.
Implanter cette fonction, et tester.
#### Ex8
Ecrire une fonction
```c
void hexdump(void * ptr,size_t size);
```
qui affiche sur la sortie standard le contenu de la mémoire `[ptr,ptr+size[` au format :
```
XXXXXXXX BB BB BB BB BB BB BB BB BB BB BB BB BB BB BB BB |CCCCCCCCCCCCCCCC|
```
(comme la commande shell)
- `XXXXXXXXX` représente l'adresse du premier octet de la ligne
- `BB` la valeur hexadécimale de chaque octet
- `|CCCCCCCCCCCCCCCC|` la correspondance ascii de chaque octet (`.` si non affichable)
Testez avec les objets suivants et expliquez :
```c
/* alignement et objets */
struct exemple1 {
int x;
int y;
int z;
int w;
};
struct exemple2 {
char x;
char y;
char z;
char w;
};
struct exemple3 {
int x;
int y;
char z;
char w;
};
struct exemple4 {
int x;
char y;
int z;
char w;
};
union exemple5 {
int x;
char y;
int z;
char w;
};
int main()
{
int a[4] = {1,2,3,4};
char c[4] = {'a','b','c','d'};
struct exemple1 ex1 = {1,2,3,4};
struct exemple2 ex2 = {'a','b','c','d'};
struct exemple3 ex3 = {1,2,'c','d'};
struct exemple4 ex4 = {1,'c',2,'d'};
union exemple5 ex5;
int x = 61;
char y = 62;
int z = 63;
char w = 64;
ex5.x=62;ex5.y=63;ex5.z=64;ex5.w=65;
// appelez hexdump pour chaque variable
return 0;
}
```
Est-ce conforme à ce que l'on a vu en cours concernant l'alignement en mémoire ?

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/* adresses virtuelles d'un processus */
#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
#include<stdlib.h>
int t[1000] = {[0 ... 999] = 2};
int main(int argc, char * argv[])
{
int i=3;
static int j = 3;
char * m = (char*)malloc(1);
printf("mon pid est %d\n\n",getpid());
/* ------- Affichage des adresses --------*/
printf("main\t=\t%p\n",main);
printf("&argc\t=\t%p\n",&argc);
printf("&i\t=\t%p\n",&i);
printf("&j\t=\t%p\n",&j);
printf("t\t=\t%p\n",t);
printf("m\t=\t%p\n",m);
getchar();
}

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/* alignement et objets */
struct exemple1 {
int x;
int y;
int z;
int w;
};
struct exemple2 {
char x;
char y;
char z;
char w;
};
struct exemple3 {
int x;
int y;
char z;
char w;
};
struct exemple4 {
int x;
char y;
int z;
char w;
};
union exemple5 {
int x;
char y;
int z;
char w;
};
int main()
{
int a[4] = {1,2,3,4};
char c[4] = {'a','b','c','d'};
struct exemple1 ex1 = {1,2,3,4};
struct exemple2 ex2 = {'a','b','c','d'};
struct exemple3 ex3 = {1,2,'c','d'};
struct exemple4 ex4 = {1,'c',2,'d'};
union exemple5 ex5;
int x = 61;
char y = 62;
int z = 63;
char w = 64;
ex5.x=62;ex5.y=63;ex5.z=64;ex5.w=65;
// appelez hexdump pour chaque variable
}

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/* segment bss et data */
#define N 1000
int t[N]; /* version 1 */
//int t[N]={1}; /* version 2 */
int main()
{
return 0;
}

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CFLAGS := -Wall -g -O0
SRC=buf.c heap.c huge.c mmap.c null.c stack.c
DEPENDHELPERS=helpers.o
BINARIES=$(SRC:%.c=%)
%.o : %c
gcc -c $+
$(BINARIES): % : %.o $(DEPENDHELPERS)
gcc -o $@ $+
all : $(BINARIES)
clean:
rm -f *.o $(BINARIES)

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#include "helpers.h"
static char buf[16 MB] = {0};
int main(int argc, char **argv)
{
randomize(buf, 16 MB);
return interlude();
}

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#include "helpers.h"
int main(int argc, char **argv)
{
dirty(16 MB);
clean(32 MB);
return interlude();
}

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#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "helpers.h"
#include <stdlib.h>
void randomize(char *buf, size_t n)
{
assert(buf);
memset(buf, rand() & 0xff, n);
}
void clean(size_t b)
{
for (; b > 0; b -= 1 KB)
calloc(1 KB, sizeof(char));
}
void dirty(size_t b)
{
for (; b > 0; b -= 1 KB)
randomize(calloc(1 KB, sizeof(char)), 1 KB);
}
int interlude(void)
{
pid_t pid = getpid();
printf("pid %i\n", (int)pid);
printf("------------------------------------------\n"
"go check /proc/%i/smaps; I'll wait...\n"
"press <Enter> when you're done\n", pid);
fgetc(stdin);
return 0;
}

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#ifndef _HELPERS_H
#define _HELPERS_H
#include <stdlib.h>
#define KB * 1024
#define MB * 1024 * 1024
void randomize(char *buf, size_t n);
void clean(size_t n);
void dirty(size_t n);
int interlude(void);
#endif

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tp/tp1/src/ex3/huge.c Normal file
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#include "helpers.h"
int main(int argc, char **argv)
{
char *under = malloc(96 KB);
randomize(under, 96 KB);
char *over = malloc(256 KB);
randomize(over, 256 KB);
return interlude();
}

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tp/tp1/src/ex3/mmap.c Normal file
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#include "helpers.h"
#include <sys/mman.h>
#include <assert.h>
#include <fcntl.h>
int main(int argc, char **argv)
{
/* inert map (never modified) */
char *inert = mmap(NULL, 16 KB,
PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE,
-1, 0);
/* anonymous, private mmap */
char *anon_priv = mmap(NULL, 32 KB,
PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE,
-1, 0);
randomize(anon_priv, 32 KB);
/* anonymous, shared map */
char *anon_shared = mmap(NULL, 64 KB,
PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_SHARED,
-1, 0);
randomize(anon_shared, 64 KB);
/* private, file-backed map */
int fd = open("data/256k", O_RDWR);
assert(fd >= 0);
char *file = mmap(NULL, 256 KB,
PROT_READ|PROT_WRITE,
MAP_PRIVATE,
fd, 0);
randomize(file, 128 KB);
return interlude();
}

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#include "helpers.h"
int main(int argc, char **argv)
{
return interlude();
}

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#include "helpers.h"
int main (int argc, char **argv)
{
char buf[28 KB] = {0};
randomize(buf, 28 KB);
return interlude();
}

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alloc.o : alloc.c alloc.h
gcc -c alloc.c
matrix.o : matrix.c
gcc -c matrix.c
matrix : matrix.o alloc.o
gcc -o matrix matrix.o alloc.o
all : matrix

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#include "alloc.h"
#include <sys/mman.h>
#include <assert.h>
#include <stdio.h>
struct my_memory_buffer {
char* buffer;
size_t pos ;
size_t size ;
};
static struct my_memory_buffer my_buf;
__attribute__((constructor))
static void my_module_initialize(void)
{
// TODO
// Init my_buf (8Mo)
// with mmap
}
void * my_alloc(size_t sz)
{
// TODO
return NULL;
}

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#ifndef _ALLOC_H
#define _ALLOC_H
#include <stdlib.h>
void * my_alloc(size_t sz);
#endif

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#include<time.h>
#include<stdio.h>
#include<stdlib.h>
#include "alloc.h"
#include <assert.h>
#define N 100
static inline double tstamp(void) {
struct timespec tv;
clock_gettime(CLOCK_REALTIME, &tv);
return tv.tv_sec + tv.tv_nsec * 1.0e-9;
}
void init_matrix(int **a,int n)
{
int i,j;
for(i=0;i<n;i++){
for(j=0;j<n;j++){
a[i][j] = 1;
}
}
}
int ** alloc_matrix(int n,int p)
{
int i;
int ** m = (int**)my_alloc(n*sizeof(int*));
assert(m != NULL);
for(i=0;i<n;i++) {
m[i] = (int*)my_alloc(p*sizeof(int));
assert(m[i] != NULL);
}
return m;
}
void mult_matrix(int **p,int **a,int **b,int n)
{
int i,j,k;
for(i=0;i<n;i++){
for(j=0;j<n;j++){
p[i][j]=0;
for(k=0;k<n;k++)
p[i][j]+=a[i][k]*b[k][j];
}
}
}
int check_matrix(int ** a,int n)
{
int i,j;
for (i=0;i<n;i++)
for (j=0;j<n;j++)
if (a[i][j] != n)
return 0;
return 1;
}
int main(int argc,char * argv[])
{
double t1,t2;
int **a,**b,**c;
t1=tstamp();
a=alloc_matrix(N,N);
b=alloc_matrix(N,N);
c=alloc_matrix(N,N);
init_matrix(a,N);
init_matrix(b,N);
mult_matrix(c,a,b,N);
t2=tstamp();
fprintf(stderr,"time = %lf\n",t2-t1);
assert(check_matrix(c,N) == 1);
}

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/* accès mémoire */
#include<stdio.h>
#include<time.h>
#include <stdlib.h>
#define N 8192
int t[N][N];
static inline double tstamp(void)
{
struct timespec tv;
clock_gettime(CLOCK_REALTIME, &tv);
return tv.tv_sec + tv.tv_nsec * 1.0e-9;
}
int main()
{
int i,j;
double t1,t2;
t1=tstamp();
/* version 1 */
for(i=0;i<N;i++) for(j=0;j<N;j++)
t[i][j] = 1;
/* version 2 */
// for(i=0;i<N;i++) for(j=0;j<N;j++)
//t[j][i] = 1;
//
t2=tstamp();
printf("time = %lf\n",t2-t1);
return 0;
}

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tp/tp1/src/scripts/parse_smaps.py Executable file
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#!/usr/bin/env python
#
# Author: Craig Chi <craig10624@gmail.com>
#
import sys
import os
import getopt
from collections import defaultdict, OrderedDict
from subprocess import check_output
def usage():
print("""
usage: parse_smaps.py [-p process_name] [-t memory_type] [-h] [smaps_filename]
example: parse_smaps.py /proc/12424/smaps
parse_smaps.py -p smbd
parse_smaps.py -p smbd -t Pss
""")
def print_header(mem_idx):
print('=' * 70)
for title in zip(*map(lambda x: x.split('_'), mem_idx.keys()),
('', '= Total : library')):
print('{:>8} + {:>8} + {:>8} + {:>8} {}'.format(*title,))
print('=' * 70)
def main():
try:
opts, args = getopt.getopt(sys.argv[1:], 'p:t:ah',
['process-name=', 'memory-type=',
'all', 'help'])
except getopt.GetoptError as err:
print(err)
sys.exit(2)
ps_name = ''
mem_type = ''
mem_idx = OrderedDict([
('Private_Clean', 0),
('Private_Dirty', 1),
('Shared_Clean', 2),
('Shared_Dirty', 3)
])
for o, a in opts:
if o in ('-p', '--process-name'):
ps_name = a
elif o in ('-t', '--memory-type'):
mem_type = a
mem_idx = {a: 0}
else:
usage()
sys.exit(2)
if (len(args) == 0 and ps_name == '') or len(args) > 1:
usage()
sys.exit(2)
smaps_file = ''
if ps_name == '':
smaps_file = os.path.abspath(args[0])
else:
try:
pids = check_output(['pidof', ps_name]).decode().strip().split()
if len(pids) > 1:
print('There are multiple pids:')
for i, p in enumerate(pids):
cmdline_file = '/proc/' + p + '/cmdline'
with open(cmdline_file, 'r') as cmdline:
line = next(cmdline)
print('[{}] {:>8}: {}'.format(i, p, line))
num = input('Choose which one process you want (default=0): ')
num = int(num) if num != '' else 0
pid = pids[num]
else:
pid = pids[0]
except Exception as err:
print(err)
sys.exit(1)
smaps_file = '/proc/' + pid + '/smaps'
mapinfo = defaultdict(lambda: [0] * len(mem_idx))
total = [0] * len(mem_idx)
with open(smaps_file, 'r') as smap:
for line in smap:
line_arr = line.split()
if '-' in line_arr[0]:
if len(line_arr) < 6:
filename = '[anonymous]'
else:
filename = os.path.basename(line_arr[-1])
else:
line_arr[0] = line_arr[0].strip(':')
if line_arr[0] in mem_idx:
mapinfo[filename][mem_idx[line_arr[0]]] += int(line_arr[1])
total[mem_idx[line_arr[0]]] += int(line_arr[1])
if mem_type == '':
print_header(mem_idx)
for filename, mem in sorted(mapinfo.items(), key=lambda x: -sum(x[1])):
print('{:>5} kB + {:>5} kB + {:>5} kB + {:>5} kB'
' = {:>5} kB : {:<}'.format(*mem, sum(mem), filename))
print('=' * 70)
print('{:>5} kB + {:>5} kB + {:>5} kB + {:>5} kB'
' = {:>5} kB : Total'.format(*total, sum(total)))
else:
for filename, mem in sorted(mapinfo.items(), key=lambda x: -sum(x[1])):
print('{:>11} kB {:<}'.format(mem[0], filename))
print('=' * 30)
print('Total: {} kB'.format(total[0]))
if __name__ == '__main__':
main()

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#!/usr/bin/python
# coding=utf-8
"""Tool to analyze and display the contents of /proc/<pid>/maps"""
import re
import itertools
import argparse
from dataclasses import dataclass
MAPS_LINE_RE = re.compile(r"""
(?P<addr_start>[0-9a-f]+)-(?P<addr_end>[0-9a-f]+)\s+ # Address
(?P<perms>\S+)\s+ # Permissions
(?P<offset>[0-9a-f]+)\s+ # Map offset
(?P<dev>\S+)\s+ # Device node
(?P<inode>\d+)\s+ # Inode
(?P<pathname>.*)\s+ # Pathname
""", re.VERBOSE)
def human_bytes(size):
modifier = 1
while size > 1024:
modifier *= 1024
size /= 1024
return "%.1f%s" % (size, {
1024**0: 'b',
1024**1: 'k',
1024**2: 'M',
1024**3: 'G',
1024**4: 'T',
}.get(modifier, " x%d" % modifier))
@dataclass
class Record:
addr_start: int
addr_end: int
perms: str
offset: int
dev: str
inode: int
pathname: str
@property
def size(self):
return self.addr_end - self.addr_start
@property
def human_size(self):
return human_bytes(self.size)
@property
def readable(self):
return self.perms[0] == "r"
@property
def writable(self):
return self.perms[1] == "w"
@property
def executable(self):
return self.perms[2] == "x"
@property
def shared(self):
return self.perms[3] == "s"
@property
def private(self):
return self.perms[3] == "p"
@classmethod
def parse(self, pid):
records = []
with open("/proc/%d/maps" % pid) as fd:
for line in fd:
m = MAPS_LINE_RE.match(line)
if not m:
print("Skipping: %s" % line)
continue
addr_start, addr_end, perms, offset, dev, inode, pathname = m.groups()
addr_start = int(addr_start, 16)
addr_end = int(addr_end, 16)
offset = int(offset, 16)
records.append(Record(
addr_start=addr_start,
addr_end=addr_end,
perms=perms,
offset=offset,
dev=dev,
inode=inode,
pathname=pathname,
))
return records
@classmethod
def aggregate(self, records, only_used=False, only_private=False):
named_records = {}
anonymous_records = []
for record in records:
if only_private and not record.private:
continue
if only_used and not record.readable and not record.writable and not record.shared and not record.pathname:
continue
if record.pathname:
if record.pathname in named_records:
other = named_records[record.pathname]
named_records[record.pathname] = Record(
min(record.addr_start, other.addr_start),
max(record.addr_end, other.addr_end),
perms=''.join("?" if c1 != c2 else c1 for c1, c2 in zip(record.perms, other.perms)),
offset=0,
dev='',
inode='',
pathname=record.pathname,
)
else:
named_records[record.pathname] = record
else:
anonymous_records.append(record)
return list(sorted(
itertools.chain(anonymous_records, named_records.values()),
key=lambda r: r.size,
reverse=True,
))
if __name__ == '__main__':
parser = argparse.ArgumentParser()
parser.add_argument("pid", type=int, help="Process identifier (pid)")
parser.add_argument("--only-used", "-u", action="store_true", help="Only show used pages (non readable, writable, executable and private pages)")
parser.add_argument("--only-private", "-p", action="store_true", help="Only show private pages")
args = parser.parse_args()
records = Record.parse(args.pid)
#records = Record.aggregate(records, only_used=args.only_used, only_private=args.only_private)
print("\t".join([
"% 16s" % "Start of range",
"% 16s" % "End of range",
"% 12s" % "Size",
"% 4s" % "Perms",
"Path",
]))
for record in records:
print("\t".join([
"%016x" % record.addr_start,
"%016x" % record.addr_end,
"% 12s" % record.human_size,
"% 4s" % record.perms,
record.pathname,
]))
print("")
print("Total: %s" % human_bytes(sum(r.size for r in records)))

108
tp/tp1/src/sum_array.c Normal file
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#include<stdio.h>
#include<time.h>
#include<stdlib.h>
#include<string.h>
#include<assert.h>
static inline double tstamp(void)
{
struct timespec tv;
clock_gettime(CLOCK_REALTIME, &tv);
return tv.tv_sec + tv.tv_nsec * 1.0e-9;
}
void shuffle(int *array, size_t n)
{
if (n > 1)
{
size_t i;
for (i = 0; i < n - 1; i++)
// for (i = 0; i < n ; i++)
{
size_t j = i + rand() / (RAND_MAX / (n - i) + 1);
// size_t j = rand()%n;
int t = array[j];
array[j] = array[i];
array[i] = t;
}
}
}
void init_access_c(int access[],size_t size)
{
int i;
for(i=0;i<size;i++) access[i] = i;
}
void init_access_d(int access[],size_t size)
{
int i;
for(i=0;i<size;i++) access[i] = size-i-1;
}
void init_access_a(int access[],size_t size)
{
init_access_c(access,size);
shuffle(access,size);
}
void init_array(int t[],int N)
{
int i;
for(i=0;i<N;i++) t[i] = i ;
}
long int sum_array(int t[],int access[],size_t size)
{
long int S=0;
int i;
for(i=0;i<size;i++) S += t[access[i]];
return S;
}
int main(int argc,char * argv[])
{
double t1,t2;
int * array; // tableau à sommer (contient les tous les entiers [0,SIZE-1]
int * access;
int i,size;
long int S=0;
if (argc !=3) {
printf("%s -c|-d|-a SIZE\n",argv[0]);
return 1;
}
size=strtol(argv[2],NULL,0);
array=(int *)malloc(sizeof(int)*size);
assert(array != NULL);
access=(int *)malloc(sizeof(int)*size);
assert(access != NULL);
init_array(array,size);
if (strcmp(argv[1],"-c") == 0)
init_access_c(access,size);
if (strcmp(argv[1],"-d") == 0)
init_access_d(access,size);
if (strcmp(argv[1],"-a") == 0)
init_access_a(access,size);
/* On somme les elements en accedant au tableau
* sequentiellement (croissant/décroissant), ou
* de manière aléatoire
* */
t1=tstamp();
S= sum_array(array,access,size);
t2=tstamp();
printf("S=%ld %lf\n",S,(t2-t1));
}