dataset.c File Reference

Training dataset loader with optional POSIX thread parallelism. More...

#include "dataset.h"
#include "../preprocess/image.h"
#include <dirent.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>

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Classes
struct	LoaderArgs
	Arguments passed to each loader thread. More...

Functions
static int	is_image_file (const char *filename)
	Check whether filename ends with a known image extension.
static void *	loader_thread (void *arg)
	POSIX thread worker: load all images from one class directory.
static size_t	count_images (const char *dir_path)
	Count the number of image files in a directory.
Dataset *	dataset_load (const char *root_dir, int n_threads)
	Load all images from root_dir into a Dataset.
void	dataset_shuffle (Dataset *ds)
	Shuffle the samples in a Dataset in-place (Fisher-Yates).
void	dataset_free (Dataset *ds)
	Free all memory owned by a Dataset.
void	dataset_print_info (const Dataset *ds)
	Print a summary of the dataset to stdout.

Detailed Description

Training dataset loader with optional POSIX thread parallelism.

Function Documentation

count_images()

size_t count_images ( const char * dir_path )

static

Count the number of image files in a directory.

Parameters

dir_path

Directory path.

Returns

Number of image files (0 if directory cannot be opened).

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dataset_free()

void dataset_free

(

Dataset *

ds

)

Free all memory owned by a Dataset.

Parameters

ds	Dataset returned by dataset_load(). No-op if NULL.

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dataset_load()

Dataset * dataset_load	(	const char *	root_dir,
		int	n_threads )

Load all images from root_dir into a Dataset.

Opens sub-directories named A–Z. For each PNG/JPG image found, loads it with SDL2, converts to grayscale, resizes to 28×28, normalises to [0, 1], and appends a Sample to the dataset. Non-image files are silently skipped.

Parameters

root_dir	Path to the training data root (e.g. "training_data/").
n_threads	Number of POSIX loader threads (1 = single-threaded).

Returns

Pointer to a heap-allocated Dataset, or NULL on error. Free with dataset_free().

Note

Requires SDL2 and SDL2_image to be linked.

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dataset_print_info()

void dataset_print_info

(

const Dataset *

ds

)

Print a summary of the dataset to stdout.

Shows the total number of samples and the per-class distribution.

Parameters

ds	Dataset to describe.

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dataset_shuffle()

void dataset_shuffle

(

Dataset *

ds

)

Shuffle the samples in a Dataset in-place (Fisher-Yates).

Parameters

ds	Dataset to shuffle.

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is_image_file()

int is_image_file ( const char * filename )

static

Check whether filename ends with a known image extension.

Accepted: .png, .jpg, .jpeg, .bmp (case-insensitive).

Parameters

filename

File name (not full path).

Returns

1 if the file is a recognised image, 0 otherwise.

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loader_thread()

void * loader_thread ( void * arg )

static

POSIX thread worker: load all images from one class directory.

Opens args->dir_path, iterates over image files, loads each one with image_load_normalised() and writes the result to args->buf.

Parameters

arg	Pointer to a heap-allocated LoaderArgs (owned by caller).

Returns

Always NULL (errors are printed to stderr).

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