3 files changed, 37 insertions(+), 6 deletions(-)

M src/bitarr.h
M src/bitarr_io.c
M src/bitarr_io.h

@@ 67,7 67,8 @@
 
 typedef enum {
   BITARR_SUCCESS,
-  OUT_OF_BOUNDS
+  OUT_OF_BOUNDS,
+  FILE_ERROR
 } BITARR_ERROR;
 
 

@@ 1,16 1,21 @@
 #include "bitarr_io.h"
 #include "bitarr.h"
 #include <stdio.h>
-#include <stdint.h>
+#include <string.h>
 
 
-// TODO: Documentation
 void BitArray_save(BitArray* bitarr, FILE *fp)
 {
+
+    // Write file identifier
+    fwrite(&BIT_MAGIC_NUMBER, sizeof(char), strlen(BIT_MAGIC_NUMBER), fp);
+
+    // BitArray metadata needed to construct data structure
     fwrite(&bitarr->l, sizeof(uint8_t), 1, fp);
     fwrite(&bitarr->width, sizeof(uint8_t), 1, fp);
     fwrite(&bitarr->n, sizeof(uint32_t), 1, fp);
 
+    // Write out compressed array
     unsigned int n_entries = 1 + (((bitarr->l * bitarr->n) - 1) / WORD_SIZE);
     fwrite(&(bitarr->v), sizeof(unsigned int), n_entries, fp);
 }


@@ 19,12 24,22 @@ BitArray* BitArray_open(FILE *fp)
 {
     uint8_t l, width;
     uint32_t n; 
+    char magic_number[strlen(BIT_MAGIC_NUMBER)]; // 3
     
+    // Verify it is a correct file
+    fread(&magic_number, sizeof(char), strlen(BIT_MAGIC_NUMBER), fp);
+    if (strcmp(magic_number, BIT_MAGIC_NUMBER) != 0) {
+        fprintf(stderr, "Incorrect file, magic string does not match\n");
+        exit(FILE_ERROR);
+    }
+
+    // Read in data to allocate memory on heap
     fread(&l, sizeof(uint8_t), 1, fp);
     fread(&width, sizeof(uint8_t), 1, fp);
     fread(&n, sizeof(uint32_t), 1, fp);
-
     BitArray* bitarr = BitArray_calloc(n, l);
+
+    // Read in compressed array
     fread(&(bitarr->v), WORD_SIZE, 1, fp);
     return bitarr;
 }

@@ 1,11 1,26 @@
 #ifndef BITARR_IO_H_
 #define BITARR_IO_H_
 
+#include <string.h>
 #include "bitarr.h"
 
+static const char BIT_MAGIC_NUMBER[] = { 'B', 'I', 'T' };
 
-// TODO: Documentation
-BitArray* BitArray_open(FILE *fp);
+/**
+ * @brief Save BitArray to disk
+ *
+ * @param bitarr    Pointer to bitarr
+ * @param fp        Filepath to save to
+ */
 void BitArray_save(BitArray* bitarr, FILE *fp);
 
+
+/**
+ * @brief Opens bitarr saved to disk
+ *
+ * @param fp    Filepath to bitarr saved on disk
+ * @return
+ */
+BitArray* BitArray_open(FILE *fp);
+
 #endif // BITARR_IO_H_