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Add slice appending code.

--- a/libstd/alloc.myr

+++ b/libstd/alloc.myr

@@ -1,12 +1,12 @@

 use "die.use"

+use "extremum.use"

 use "sys.use"

 use "types.use"

-use "extremum.use"

-/* 

+/*

 The allocator implementation here is based on Bonwick's slab allocator.

-For small allocations (up to Bucketmax), it works by requesting large,

+For small allocations (up to Bktmax), it works by requesting large,

 power of two aligned chunks from the operating system, and breaking

 them into a linked list of equal sized chunks. Allocations are then

 satisfied by taking the head of the list of chunks. Empty slabs

@@ -13,7 +13,7 @@

 are removed from the freelist.

 The data structure looks something like this:

-   Buckets:

+   Bkts:

 	[16  byte] -> [slab hdr | chunk -> chunk -> chunk] -> [slab hdr | chunk -> chunk -> chunk]

 	[32  byte] -> Zslab

 	[64  byte] -> [slab hdr | chunk -> chunk]

@@ -34,6 +34,9 @@

 	const bytealloc	: (sz:size	-> byte#)

 	const bytefree	: (m:byte#, sz:size	-> void)

+

+	/* FIXME: This should be automatically exported as a hidden decl. */

+	const samebucket

 ;;

 /* null pointers. only used internally. */

@@ -43,7 +46,7 @@

 const Slabsz 	= 1048576	/* 1 meg slabs */

 const Cachemax	= 16	/* maximum number of slabs in the cache */

-const Bucketmax	= 32768	/* Slabsz / 8; a balance. */

+const Bktmax	= 32768	/* Slabsz / 8; a balance. */

 const Align	= 16	/* minimum allocation alignment */

 var buckets	: bucket[32] /* excessive */

@@ -92,20 +95,35 @@

 }

 /* Grows a slice */

-generic slgrow = {sl, len

+generic slgrow = {sl : @a[:], len

 	var i

 	var n

 	var new

+	/* if the slice wouldn't change buckets, we don't need to realloc. */

+	if samebucket(sl.len * sizeof(@a), len * sizeof(@a))

+		-> sl

+	;;

+

 	new = slalloc(len)

 	n = min(len, sl.len)

 	for i = 0; i < n; i++

 		new[i] = sl[i]

 	;;

-	slfree(sl)

+	if sl.len > 0

+		slfree(sl)

+	;;

 	-> new

 }

+const samebucket = {oldsz, newsz

+	if oldsz > 0 && newsz < Bktmax

+		-> bktnum(oldsz) == bktnum(newsz)

+	else

+		-> false

+	;;

+}

+

 /* Allocates a blob that is 'sz' bytes long. Dies if the allocation fails */

 const bytealloc = {sz

 	var i

@@ -112,13 +130,13 @@

 	var bkt

 	if !initdone

-		for i = 0; i < buckets.len && (Align << i) <= Bucketmax; i++

+		for i = 0; i < buckets.len && (Align << i) <= Bktmax; i++

 			bktinit(&buckets[i], Align << i)

 		;;

 		initdone = 1

 	;;

-	if (sz <= Bucketmax)

+	if (sz <= Bktmax)

 		bkt = &buckets[bktnum(sz)]

 		-> bktalloc(bkt)

 	else

@@ -130,7 +148,7 @@

 const bytefree = {m, sz

 	var bkt

-	if (sz < Bucketmax)

+	if (sz < Bktmax)

 		bkt = &buckets[bktnum(sz)]

 		bktfree(bkt, m)

 	else

@@ -258,7 +276,7 @@

 	var bktsz

 	bktsz = Align

-	for i = 0; bktsz <= Bucketmax; i++

+	for i = 0; bktsz <= Bktmax; i++

 		if bktsz >= sz

 			-> i

 		;;

--- /dev/null

+++ b/libstd/slappend.myr

@@ -1,0 +1,11 @@

+use "alloc.use"

+

+pkg std =

+	generic slappend	: (sl : @a[:], v : @a	-> @a[:])

+;;

+

+generic slappend = {sl, v

+	sl = slgrow(sl, sl.len + 1)

+	sl[sl.len - 1] = v

+	-> sl

+}