Sorting function cleanup and MinGW fix

Clean up some sorting function stuff including fixing qsort_r
on MinGW, common function pointer type for comparison, and basic
insertion sort implementation (which we, regrettably, fall back
on for MinGW).

src/tsort.c

@@ -24,7 +24,7 @@
 #endif
 
 static int binsearch(
-	void **dst, const void *x, size_t size, git__tsort_r_cmp cmp, void *payload)
+	void **dst, const void *x, size_t size, git__sort_r_cmp cmp, void *payload)
 {
 	int l, c, r;
 	void *lx, *cx;
@@ -71,7 +71,7 @@ static int binsearch(
 
 /* Binary insertion sort, but knowing that the first "start" entries are sorted. Used in timsort. */
 static void bisort(
-	void **dst, size_t start, size_t size, git__tsort_r_cmp cmp, void *payload)
+	void **dst, size_t start, size_t size, git__sort_r_cmp cmp, void *payload)
 {
 	size_t i;
 	void *x;
@@ -102,7 +102,7 @@ struct tsort_run {
 
 struct tsort_store {
 	size_t alloc;
-	git__tsort_r_cmp cmp;
+	git__sort_r_cmp cmp;
 	void *payload;
 	void **storage;
 };
@@ -334,7 +334,7 @@ static ssize_t collapse(void **dst, struct tsort_run *stack, ssize_t stack_curr,
 while (0)
 
 void git__tsort_r(
-	void **dst, size_t size, git__tsort_r_cmp cmp, void *payload)
+	void **dst, size_t size, git__sort_r_cmp cmp, void *payload)
 {
 	struct tsort_store _store, *store = &_store;
 	struct tsort_run run_stack[128];

src/util.c

@@ -610,7 +610,7 @@ size_t git__unescape(char *str)
 
 #if defined(GIT_WIN32) || defined(BSD)
 typedef struct {
-	git__qsort_r_cmp cmp;
+	git__sort_r_cmp cmp;
 	void *payload;
 } git__qsort_r_glue;
 
@@ -623,17 +623,39 @@ static int GIT_STDLIB_CALL git__qsort_r_glue_cmp(
 #endif
 
 void git__qsort_r(
-	void *els, size_t nel, size_t elsize, git__qsort_r_cmp cmp, void *payload)
+	void *els, size_t nel, size_t elsize, git__sort_r_cmp cmp, void *payload)
 {
-#if defined(GIT_WIN32)
+#if defined(__MINGW32__)
+	git__insertsort_r(els, nel, elsize, NULL, cmp, payload);
+#elif defined(GIT_WIN32)
 	git__qsort_r_glue glue = { cmp, payload };
 	qsort_s(els, nel, elsize, git__qsort_r_glue_cmp, &glue);
-#else
-#if defined(BSD)
+#elif defined(BSD)
 	git__qsort_r_glue glue = { cmp, payload };
 	qsort_r(els, nel, elsize, &glue, git__qsort_r_glue_cmp);
 #else
 	qsort_r(els, nel, elsize, cmp, payload);
 #endif
-#endif
+}
+
+void git__insertsort_r(
+	void *els, size_t nel, size_t elsize, void *swapel,
+	git__sort_r_cmp cmp, void *payload)
+{
+	uint8_t *base = els, *end = els + nel * elsize;
+	uint8_t *i, *j;
+	bool freeswap = !swapel;
+
+	if (freeswap)
+		swapel = git__malloc(elsize);
+
+	for (i = base + elsize; i < end; i += elsize)
+		for (j = i; j > base && cmp(j, j - elsize, payload) < 0; j -= elsize) {
+			memcpy(swapel, j, elsize);
+			memcpy(j, j - elsize, elsize);
+			memcpy(j - elsize, swapel, elsize);
+		}
+
+	if (freeswap)
+		git__free(swapel);
 }

src/util.h

@@ -146,15 +146,17 @@ typedef int (*git__tsort_cmp)(const void *a, const void *b);
 
 extern void git__tsort(void **dst, size_t size, git__tsort_cmp cmp);
 
-typedef int (*git__tsort_r_cmp)(const void *a, const void *b, void *payload);
+typedef int (*git__sort_r_cmp)(const void *a, const void *b, void *payload);
 
 extern void git__tsort_r(
-	void **dst, size_t size, git__tsort_r_cmp cmp, void *payload);
-
-typedef int (*git__qsort_r_cmp)(const void *a, const void *b, void *payload);
+	void **dst, size_t size, git__sort_r_cmp cmp, void *payload);
 
 extern void git__qsort_r(
-	void *els, size_t nel, size_t elsize, git__qsort_r_cmp cmp, void *payload);
+	void *els, size_t nel, size_t elsize, git__sort_r_cmp cmp, void *payload);
+
+extern void git__insertsort_r(
+	void *els, size_t nel, size_t elsize, void *swapel,
+	git__sort_r_cmp cmp, void *payload);
 
 /**
  * @param position If non-NULL, this will be set to the position where the