From e8a35c273d18faef1c6fee5bb984a02273377408 Mon Sep 17 00:00:00 2001
From: Alex 'AdUser' Z <ad_user@runbox.com>
Date: Wed, 13 May 2015 17:56:33 +1000
Subject: [PATCH] * imdb_usage_slice()

---
 src/database.c | 25 +++++++++++++++++++++++++
 src/database.h | 13 +++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/src/database.c b/src/database.c
index 6a8e026..2d14fc8 100644
--- a/src/database.c
+++ b/src/database.c
@@ -323,3 +323,28 @@ imdb_usage_map(imdb_db_t * const db,
 
   return records;
 }
+
+uint16_t
+imdb_usage_slice(imdb_db_t * const db,
+                 char     ** const map,
+                 uint64_t  offset,
+                 uint16_t  limit) {
+  imdb_block_t blk;
+  unsigned char *r; /* mnemonics : block, record */
+  char *m = NULL;   /* mnemonics : map */
+
+  memset(&blk, 0x0, sizeof(imdb_block_t));
+  CALLOC(*map, limit + 1, sizeof(char));
+
+  m = *map;
+  blk.start = offset;
+  blk.records = limit;
+
+  limit = imdb_read_blk(db, &blk);
+  r = blk.data;
+  for (uint16_t i = 0;  i < blk.records;  i++, m++, r += IMDB_REC_LEN) {
+    *m = (r[REC_OFF_RU] == 0xFF) ? CHAR_USED : CHAR_NONE;
+  }
+
+  return limit;
+}
diff --git a/src/database.h b/src/database.h
index 4e80774..0380c30 100644
--- a/src/database.h
+++ b/src/database.h
@@ -130,4 +130,17 @@ imdb_records_count(imdb_db_t * const db);
 uint64_t
 imdb_usage_map(imdb_db_t * const db,
                char     ** const map);
+
+/**
+  @brief   fills buffer 'map' according to records existense in given range
+  @param   offset  start of slice position
+  @param   limit   slice size
+  @returns records processed (and also buffer size)
+*/
+uint16_t
+imdb_usage_slice(imdb_db_t * const db,
+                 char     ** const map,
+                 uint64_t  offset,
+                 uint16_t  limit);
+
 #endif