Initial working version of table.c

src/table.c

@@ -0,0 +1,150 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#define TABLE_INCREMENT       5
+#define TABLE_HAS_ID          1
+#define TABLE_HAS_CREATED_AT  2
+#define TABLE_HAS_UPDATED_AT  4
+
+typedef struct {
+    unsigned long  flags;
+    unsigned long  record_size;
+    unsigned long  number_of_slots;
+    unsigned long  number_of_records;
+    unsigned long  autoincrement;
+    unsigned char *records;
+    unsigned char *index;
+} Table, *PTable;
+
+
+PTable table_initialize(unsigned long record_size, unsigned long flags) {
+    PTable pt;
+
+    pt = calloc(1, sizeof(Table));
+    pt->flags             = flags | TABLE_HAS_ID;
+    pt->record_size       = record_size;
+    pt->number_of_slots   = TABLE_INCREMENT;
+    pt->number_of_records = 0;
+    pt->autoincrement     = 0;
+    pt->records           = calloc(TABLE_INCREMENT, pt->record_size);
+    pt->index             = calloc(TABLE_INCREMENT, sizeof(unsigned long *));
+
+    return pt;
+}
+
+unsigned char *table_next_record(PTable pt) {
+    return pt->records + pt->number_of_records * pt->record_size;
+}
+
+unsigned char *table_last_record(PTable pt) {
+    if (pt->number_of_records == 0) {
+        return pt->records;
+    } else {
+        return table_next_record(pt) - pt->record_size;
+    }
+}
+
+unsigned char *table_next_index(PTable pt) {
+    return pt->index + pt->autoincrement * sizeof(unsigned long *);
+}
+
+unsigned char *table_last_index(PTable pt) {
+    if (pt->autoincrement == 0) {
+        return pt->index;
+    } else {
+        return table_last_index(pt) - sizeof(unsigned long *);
+    }
+}
+
+
+PTable table_extend(PTable pt) {
+    register long i;
+    unsigned long *pi;
+
+    pt->number_of_slots += TABLE_INCREMENT;
+
+    /* Re-allocate the records and set newly added memory chunk to 0. */
+    pt->records = realloc(pt->records, pt->number_of_slots * pt->record_size);
+    memset(table_next_record(pt), 0, TABLE_INCREMENT * pt->record_size);
+
+    /* Re-allocate the index and set newly added memory chunk to 0. */
+    pt->index = realloc(pt->index, pt->number_of_slots * sizeof(unsigned long *));
+    memset(table_next_index(pt), 0, TABLE_INCREMENT * sizeof(unsigned long *));
+
+    /* Reassign index entries to point to the re-allocatted records. */
+    for (i = 0, pi = (unsigned long *)pt->index;  i < pt->autoincrement;  i++, pi++) {
+        *pi = (unsigned long)(pt->records + pt->record_size * i);
+    }
+
+    return pt;
+}
+
+unsigned long *table_find(PTable pt, unsigned long id) {
+    if (pt->number_of_records == 0 || id < 0 || id > pt->autoincrement) {
+        return NULL;
+    } else {
+        return (unsigned long *) *((unsigned long *)pt->index + id);
+    }
+}
+
+PTable table_insert(PTable pt, unsigned long *record) {
+    unsigned long **pi;
+
+    if (pt->number_of_records >= pt->number_of_slots) {
+        pt = table_extend(pt);
+    }
+
+    memmove(table_next_record(pt), record, pt->record_size);
+    // printf("rec: %lu, %08lX, mov: %08lX, next: %08lX\n", (unsigned long)*record, (unsigned long)*record, (unsigned long)*table_next_record(pt), (unsigned long)table_next_record(pt));
+    pi = (unsigned long **)table_next_index(pt);
+    
+    *pi = (unsigned long *)table_next_record(pt);
+    pt->number_of_records++;
+    pt->autoincrement++;
+
+    return pt;
+}
+
+
+
+PTable table_free(PTable pt) {
+    if (pt) {
+        if (pt->index) {
+            free(pt->index);
+        }
+        if (pt->records) {
+            free(pt->records);
+        }
+        free(pt);
+    }
+
+    return NULL;
+}
+
+
+int main() {
+    PTable pt;
+    typedef struct {
+        unsigned long id;
+        char name[30];
+    } Record;
+
+    Record rec, *prec;
+    int i;
+
+    pt = table_initialize(sizeof(Record), 0);
+    for(i = 0;  i <= 100;  i++) {
+        rec.id = i;
+        pt = table_insert(pt, (unsigned long *)&rec);
+        printf("%08lX, %08lX\n", (unsigned long)*table_last_record(pt), (unsigned long)table_last_record(pt));
+    }
+
+    for(i = 100;  i >= 0;  i--) {
+        prec = (Record *)table_find(pt, i);
+        printf("%lu\n", prec->id);
+    }
+
+    table_free(pt);
+    printf("OK\n");
+}