From 422d2fd579bc67b058b74d19d23b3497c7392d46 Mon Sep 17 00:00:00 2001
From: Jonas 'Sortie' Termansen <sortie@maxsi.org>
Date: Mon, 5 Mar 2012 12:37:59 +0100
Subject: [PATCH] Added qsort(3).

This is a rather slow implementation. Will be fixed soon.
---
 libmaxsi/Makefile         |  1 +
 libmaxsi/include/stdlib.h |  2 +-
 libmaxsi/sort.cpp         | 62 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 libmaxsi/sort.cpp

diff --git a/libmaxsi/Makefile b/libmaxsi/Makefile
index 21d0589e..16dce0ee 100644
--- a/libmaxsi/Makefile
+++ b/libmaxsi/Makefile
@@ -51,6 +51,7 @@ integer.o \
 c++.o \
 memory.o \
 heap.o \
+sort.o \
 string.o \
 error.o \
 format.o \
diff --git a/libmaxsi/include/stdlib.h b/libmaxsi/include/stdlib.h
index e134889f..53235971 100644
--- a/libmaxsi/include/stdlib.h
+++ b/libmaxsi/include/stdlib.h
@@ -53,6 +53,7 @@ void _Exit(int status);
 void free(void*);
 char* getenv(const char*);
 void* malloc(size_t);
+void qsort(void*, size_t, size_t, int (*)(const void*, const void*));
 int rand(void);
 void* realloc(void*, size_t);
 long strtol(const char* restrict, char** restrict, int);
@@ -98,7 +99,6 @@ int posix_memalign(void**, size_t, size_t);
 int posix_openpt(int);
 char* ptsname(int);
 int putenv(char*);
-void qsort(void*, size_t, size_t, int (*)(const void*, const void*));
 long random(void);
 char* realpath(const char* restrict, char* restrict);
 unsigned short *seed48(unsigned short [3]);
diff --git a/libmaxsi/sort.cpp b/libmaxsi/sort.cpp
new file mode 100644
index 00000000..5c28af7d
--- /dev/null
+++ b/libmaxsi/sort.cpp
@@ -0,0 +1,62 @@
+/*******************************************************************************
+
+	COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2012.
+
+	This file is part of LibMaxsi.
+
+	LibMaxsi is free software: you can redistribute it and/or modify it under
+	the terms of the GNU Lesser General Public License as published by the Free
+	Software Foundation, either version 3 of the License, or (at your option)
+	any later version.
+
+	LibMaxsi is distributed in the hope that it will be useful, but WITHOUT ANY
+	WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+	FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
+	details.
+
+	You should have received a copy of the GNU Lesser General Public License
+	along with LibMaxsi. If not, see <http://www.gnu.org/licenses/>.
+
+	sort.cpp
+	Utility functions related to sorting and sorted data.
+
+*******************************************************************************/
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+// TODO: This is an ugly hack!
+static void memswap(uint8_t* a, uint8_t* b, size_t size)
+{
+	uint8_t* tmp = (uint8_t*) malloc(size);
+	if ( !tmp ) { abort(); }
+	memcpy(tmp, a, size);
+	memcpy(a, b, size);
+	memcpy(b, tmp, size);
+	free(tmp);
+}
+
+// TODO: This is just a quick and dirty insertion sort. It'd be nice to have a
+// good old quick sort here soon. Combined with the slow memswap above, this
+// results in a very slow sorting algorithm.
+extern "C" void qsort(void* base, size_t nmemb, size_t size,
+                      int (* compare)(const void*, const void*))
+{
+	uint8_t* buf = (uint8_t*) base;
+	for ( size_t i = 0; i < nmemb; i++ )
+	{
+		for ( size_t c = i; c; c-- )
+		{
+			size_t currentoff = c * size;
+			uint8_t* current = buf + currentoff;
+			size_t p = c-1;
+			size_t prevoff = p * size;
+			uint8_t* prev = buf + prevoff;
+			int cmp = compare(prev, current);
+			if ( cmp <= 0 ) { break; }
+			memswap(prev, current, size);
+		}
+	}
+}
+