Added bsearch

bake.cmd

@@ -51,4 +51,4 @@ del build\*.obj
 
 :skip_crt_compilation
 echo Compiling test..
-clang test\test.c ciabatta.lib -std=c11 -lkernel32 -luser32 -lshell32 -nostdlib %CIABATTA_OPTIONS%
+clang test\test4.c ciabatta.lib -std=c11 -lkernel32 -luser32 -lshell32 -nostdlib %CIABATTA_OPTIONS%

code/stdlib.c

@@ -0,0 +1,18 @@
+#include <stdlib.h>
+
+const void *bsearch(const void *key, const void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *)) {
+    size_t left = 0;
+    size_t right = nmemb;
+
+    const char* buffer = base;
+    while (left < right) {
+        size_t middle = (left + right) / 2;
+
+        int cmp = compar(&buffer[middle * size], key);
+        if (cmp == 0) return &buffer[left * size];
+        if (cmp < 0) left = middle + 1;
+        else right = middle;
+    }
+
+    return NULL;
+}

inc/stdlib.h

@@ -71,7 +71,7 @@ _Noreturn void _Exit(int status);
 char *getenv(const char *name);
 // _Noreturn void quick_exit(int status);
 // int system(const char *string);
-// void *bsearch(const void *key, const void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *));
+const void *bsearch(const void *key, const void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *));
 // void qsort(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *));
 // int abs(int j);
 // long int labs(long int j);

test/test4.c

@@ -0,0 +1,34 @@
+// https://en.cppreference.com/w/c/algorithm/bsearch
+#include <stdlib.h>
+#include <stdio.h>
+
+struct data {
+    int nr;
+    char const *value;
+} dat[] = {
+    {1, "Foo"}, {2, "Bar"}, {3, "Hello"}, {4, "World"}
+};
+
+int data_cmp(void const *lhs, void const *rhs)
+{
+    struct data const *const l = lhs;
+    struct data const *const r = rhs;
+
+    if (l->nr < r->nr) return -1;
+    else if (l->nr > r->nr) return 1;
+    else return 0;
+
+    // return (l->nr > r->nr) - (l->nr < r->nr); // possible shortcut
+    // return l->nr - r->nr; // erroneous shortcut (fails if INT_MIN is present)
+}
+
+int main(void)
+{
+    struct data key = { .nr = 3 };
+    struct data const *res = bsearch(&key, dat, sizeof dat / sizeof dat[0], sizeof dat[0], data_cmp);
+    if (res) {
+        printf("No %d: %s\n", res->nr, res->value);
+    } else {
+        printf("No %d not found\n", key.nr);
+    }
+}