Finish porting SD code

main
Anthony Wang 10 months ago
parent 74b018bf1c
commit 9009a690b9
Signed by: a
GPG Key ID: BC96B00AEC5F2D76

@ -6,7 +6,7 @@ C port of [SD](https://git.exozy.me/Ta180m/SD), a very efficient flash cards app
Flash cards are stored in the `cards` table of a SQLite database. There are four columns: `idx INTEGER PRIMARY KEY, weight INTEGER, key STRING, val STRING`. The `idx` is a unique index for each card, starting at 0. The weight is how often the card should come up. The key and value are the front and reverse sides of the card. You can use the `sqlite3` CLI to create a card deck.
Now build this project with `gcc cd.c -o cd -l sqlite3 -O2 -march=native` and run `./cd` to enjoy a fast flash cards experience! The program will display the `key` of a randomly selected card. Press any key to show the `val` of the card. Now press either `y` or `n` depending on whether you got the card correct, and the program adjusts that card's weight.
Now build this project with `gcc cd.c segmenttree.c -o cd -lsqlite3 -O2 -march=native` and run `./cd` to enjoy a fast flash cards experience! The program will display the `key` of a randomly selected card. Press any key to show the `val` of the card. Now press either `y` or `n` depending on whether you got the card correct, and the program adjusts that card's weight.
If you're wondering where the name came from, this is the C port of [SD](https://git.exozy.me/Ta180m/SD).

98
cd.c

@ -2,6 +2,7 @@
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <getopt.h>
#include <sqlite3.h>
@ -11,9 +12,10 @@ int main(int argc, char* argv[]) {
char *file = "cards";
bool verbose = false;
/* Proccess args */
static struct option long_options[] = {
{"file", required_argument, 0, 'f'},
{"verbose", no_argument, 0, 'v'}
{"file", required_argument, NULL, 'f'},
{"verbose", no_argument, NULL, 'v'}
};
while (1) {
int option_index = 0;
@ -26,17 +28,103 @@ int main(int argc, char* argv[]) {
}
}
printf("%s", file);
/* Seed the RNG */
srand(time(0));
/* Connect to db */
sqlite3 *db;
int rc = sqlite3_open(file, &db);
if (rc) {
fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
abort();
}
fprintf(stderr, "Opened database successfully\n");
//int N = sqlite3_exec(db, "SELECT COUNT(*) FROM cards", callback)
/* Get number of cards */
sqlite3_stmt *stmt;
rc = sqlite3_prepare_v3(db, "SELECT COUNT(*) FROM cards", -1, 0, &stmt, NULL);
if (rc != SQLITE_OK) {
fprintf(stderr, "Database error: %s\n", sqlite3_errmsg(db));
abort();
}
sqlite3_step(stmt);
int N = sqlite3_column_int(stmt, 0);
sqlite3_finalize(stmt);
/* Get card weights */
rc = sqlite3_prepare_v3(db, "SELECT weight FROM cards", -1, 0, &stmt, NULL);
if (rc != SQLITE_OK) {
fprintf(stderr, "Database error: %s\n", sqlite3_errmsg(db));
abort();
}
seg = malloc(4 * N * sizeof(int));
build(stmt, 0, N - 1, 1);
sqlite3_finalize(stmt);
if (verbose) {
for (int i = 0; i < N; i++) {
printf("%d ", seg[i]);
}
printf("\n");
}
/* Disable input buffering */
system("stty -F /dev/tty cbreak min 1");
system("stty -F /dev/tty -echo");
while (true) {
int x = (long long)rand() * rand() % seg[1];
int res[2];
query(res, x, 0, N-1, 1);
int w = res[0], i = res[1];
if (verbose) {
printf("%d %d %d %d\n", seg[1], x, w, i);
}
/* Get card contents from database */
rc = sqlite3_prepare_v3(db, "SELECT key, val FROM cards WHERE idx=?", -1, 0, &stmt, NULL);
if (rc != SQLITE_OK) {
fprintf(stderr, "Database error: %s\n", sqlite3_errmsg(db));
abort();
}
sqlite3_bind_int(stmt, 1, i);
sqlite3_step(stmt);
char *key, *val;
key = strdup(sqlite3_column_text(stmt, 0));
val = strdup(sqlite3_column_text(stmt, 1));
sqlite3_finalize(stmt);
printf("> %s\n", key);
/* Wait for confirmation */
char b = getchar();
printf("%s\n", val);
/* Read user input */
b = getchar();
if (b == 'y') {
w >>= 1;
}
else if (b == 'n') {
w <<= 3;
}
else {
break;
}
/* Update segment tree and database */
update(i, w, 0, N - 1, 1);
rc = sqlite3_prepare_v3(db, "UPDATE cards SET weight=? WHERE idx=?", -1, 0, &stmt, NULL);
if (rc != SQLITE_OK) {
fprintf(stderr, "Database error: %s\n", sqlite3_errmsg(db));
abort();
}
sqlite3_bind_int(stmt, 1, w);
sqlite3_bind_int(stmt, 2, i);
sqlite3_finalize(stmt);
}
/* Cleanup */
system("stty -F /dev/tty echo");
sqlite3_close(db);
}

@ -1,46 +1,48 @@
struct SegmentTree {
int N;
int * seg;
}
#include <sqlite3.h>
int * seg;
// Build segment tree
void Build(int l, int r, int n) {
/* Build segment tree */
void build(sqlite3_stmt *stmt, int l, int r, int n) {
if (l == r) {
sqlite3_step(stmt);
seg[l] = sqlite3_column_int(stmt, 0);
return;
}
int m = l + r >> 1;
Build(l, m, n << 1);
Build(m + 1, r, n << 1 | 1);
build(stmt, l, m, n << 1);
build(stmt, m + 1, r, n << 1 | 1);
seg[n] = seg[n << 1] + seg[n << 1 | 1];
}
// Update value at index x
void Update(int x, int v, int l, int r, int n) {
/* Update value at index x*/
void update(int x, int v, int l, int r, int n) {
if (l == r) {
seg[n] += v;
return;
}
int m = l + r >> 1;
if (x <= m) {
Update(x, v, l, m, n<<1);
update(x, v, l, m, n<<1);
}
else {
Update(x, v, m+1, r, n<<1|1);
update(x, v, m+1, r, n<<1|1);
}
seg[n] = seg[n << 1] + seg[n << 1 | 1];
}
// Find element with prefix sum v
int Query(int v, int l, int r, int n) {
/* Find element with prefix sum v */
void query(int *res, int v, int l, int r, int n) {
if (l == r) {
return s.seg[n], l;
res[0] = seg[n];
res[1] = l;
return;
}
int m = l + r >> 1;
if (seg[n << 1] >= v) {
return Query(v, l, m, n << 1);
query(res, v, l, m, n << 1);
}
else {
return Query(v - s.seg[n << 1], m + 1, r, n << 1 | 1);
query(res, v - seg[n << 1], m + 1, r, n << 1 | 1);
}
}
}

@ -1 +1,9 @@
struct SegmentTree;
#include <sqlite3.h>
extern int * seg;
void build(sqlite3_stmt *stmt, int l, int r, int n);
void update(int x, int v, int l, int r, int n);
void query(int *res, int v, int l, int r, int n);
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