write some constants for mcx.c, so things are less error-prone.

src/dat/mcx.c

@@ -9,18 +9,22 @@
 #include "../util/compat/endian.h"
 #include "../util/intdef.h"
 
+#define TABLE  0x2000 // table byte size
+#define SECTOR 0x1000 // sector size
+#define CHUNKS 0x400  // amount of chunks in a file
+
 /* Moves chunks `src_s` to `src_e` (inclusive) from `src`, back onto `dst`. */
 static void mvchunks(u8 *restrict buf, u8 *src, u8 *dst, int src_s, int src_e) {
 	assert(src > dst);
 	u32 *table = (u32 *)buf;
 	size_t len = src - dst; // acquire the amount of bytes that we shall move
-	assert(!(len % 0x1000));
+	assert(!(len % SECTOR));
 
 	// count how many bytes we need to move, whilst updating location data
 	size_t blen = 0;
 	for (src_s++; src_s <= src_e; src_s++) {
-		blen += (be32toh(table[src_s]) & 0xFF) * 0x1000;
-		table[src_s] -= htobe32((len / 0x1000) << 8);
+		blen += (be32toh(table[src_s]) & 0xFF) * SECTOR;
+		table[src_s] -= htobe32((len / SECTOR) << 8);
 	}
 	memmove(dst, src, blen);
 }
@@ -33,12 +37,12 @@ static size_t delchunk(u8 *restrict buf, size_t rmb, int sidx, int eidx) {
 	u32 *table = (u32 *)buf;
 	size_t slen, bidx, blen;
 	slen = be32toh(table[sidx]) & 0xFF;          // acquire the sector length of the chunk
-	bidx = (be32toh(table[sidx]) >> 8) * 0x1000; // acquire and compute the byte offset the chunk starts at
-	blen = slen * 0x1000;                        // compute the byte length of the chunk
+	bidx = (be32toh(table[sidx]) >> 8) * SECTOR; // acquire and compute the byte offset the chunk starts at
+	blen = slen * SECTOR;                        // compute the byte length of the chunk
 
 	// reset the table data
 	table[sidx] = 0;
-	table[sidx + 0x400] = htobe32(time(NULL)); // assign the current time to the timestamp, for correctness  NOTE: might need to zero-out instead
+	table[sidx + CHUNKS] = htobe32(time(NULL)); // assign the current time to the timestamp, for correctness  NOTE: might need to zero-out instead
 
 	// move the succeeding chunks over the deleted chunk
 	u8 *dst = buf + bidx - rmb;
@@ -51,26 +55,26 @@ static size_t delchunk(u8 *restrict buf, size_t rmb, int sidx, int eidx) {
  * This is done instead of `delchunk` being globally linked, because
  * `delchunk` requests more specific parameters, which is confusing outside this module. */
 size_t mcx_delchunk(u8 *restrict buf, int chunk) {
-	return delchunk(buf, 0, chunk, 0x400);
+	return delchunk(buf, 0, chunk, CHUNKS);
 }
 
 size_t mcx_delchunk_range(u8 *restrict buf, int start, int end) {
-	assert(start < end && end < 0x400);
+	assert(start < end && end < CHUNKS);
 	u32 *table = (u32 *)buf;
-	u8 *dst = buf + (be32toh(table[start]) >> 8) * 0x1000;
-	u8 *src = buf + (be32toh(table[end]) >> 8) * 0x1000;
-	src += (be32toh(table[end]) & 0xFF) * 0x1000;
+	u8 *dst = buf + (be32toh(table[start]) >> 8) * SECTOR;
+	u8 *src = buf + (be32toh(table[end]) >> 8) * SECTOR;
+	src += (be32toh(table[end]) & 0xFF) * SECTOR;
 
 	// zeroes-out the chunk data within this range. (and set the timestamp)
 	u32 ts = htobe32(time(NULL));
 	for (int i = start; i <= end; i++) {
 		table[i] = 0;
-		table[i + 0x400] = ts;
+		table[i + CHUNKS] = ts;
 	}
 
 	// move the remaining chunks down
-	if (end < 0x3FF)
-		mvchunks(buf, src, dst, end, 0x3FF);
+	if (end < (CHUNKS - 1))
+		mvchunks(buf, src, dst, end, (CHUNKS - 1));
 	return src - dst;
 }
 
@@ -88,7 +92,7 @@ size_t mcx_delchunk_bulk(u8 *restrict buf, const u16 *restrict chunks, int chunk
 	u16 chunkids[chunkc + 1];
 	memcpy(chunkids, chunks, chunkc);
 	qsort(chunkids, chunkc, sizeof(int), cmp_chunkids);
-	chunkids[chunkc] = 0x400; // set the spare chunk to the max chunks, so the rest of the chunks are moved
+	chunkids[chunkc] = CHUNKS; // set the spare chunk to the max chunks, so the rest of the chunks are moved
 
 	size_t rmb = 0;
 	for (int i = 0; i < chunkc; i++)
@@ -97,10 +101,10 @@ size_t mcx_delchunk_bulk(u8 *restrict buf, const u16 *restrict chunks, int chunk
 }
 
 /* Sum together the 4th byte in each location integer to compute the sector size of all chunks.
- * Multiplying by `0x1000`, and adding the size of the table itself. */
+ * Multiplying by `SECTOR`, and adding the size of the table itself. */
 size_t mcx_calcsize(const u8 *restrict buf) {
 	size_t size = 0;
-	for (uint i = 0; i < 0x400; i++)
+	for (uint i = 0; i < CHUNKS; i++)
 		size += *(buf + (i * 4) + 3);
-	return (size * 0x1000) + 0x2000;
+	return (size * CHUNKS) + TABLE;
 }