[libcrystax] Add swab implementation (issue #1252)

Signed-off-by: Dmitry Moskalchuk <dm@crystax.net>

sources/crystax/bin/gen-bsd-sources

@@ -993,6 +993,7 @@ g.add "lib/libc/string/strspn.c",          warnings: "sign-compare"
 g.add "lib/libc/string/strstr.c"
 g.add "lib/libc/string/strtok.c"
 g.add "lib/libc/string/strxfrm.c",         fixup:    "collate_fixwarnings"
+g.add "lib/libc/string/swab.c"
 g.add "lib/libc/string/wcpcpy.c"
 g.add "lib/libc/string/wcpncpy.c"
 g.add "lib/libc/string/wcscasecmp.c"

tests/device/crystax-issue1252-swab/jni/Android.mk

@@ -0,0 +1,8 @@
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE     := test
+LOCAL_SRC_FILES  := main.c
+LOCAL_CFLAGS     := -Wall -Wextra -Werror
+LOCAL_CFLAGS     += -UNDEBUG
+include $(BUILD_EXECUTABLE)

tests/device/crystax-issue1252-swab/jni/Application.mk

@@ -0,0 +1 @@
+APP_ABI := all

tests/device/crystax-issue1252-swab/jni/main.c

@@ -0,0 +1,36 @@
+#include <assert.h>
+#include <unistd.h>
+#include <stdint.h>
+
+int main()
+{
+    uint8_t src[] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07};
+    uint8_t dst[sizeof(src)/sizeof(src[0])];
+
+    swab(NULL, NULL, -1);
+
+    memset(dst, 0, sizeof(dst));
+    swab(src, dst, -1);
+    assert(dst[0] == 0);
+
+    memset(dst, 0, sizeof(dst));
+    swab(src, dst, 0);
+    assert(dst[0] == 0);
+
+    memset(dst, 0, sizeof(dst));
+    swab(src, dst, 2);
+    assert(dst[0] == 0x02);
+    assert(dst[1] == 0x01);
+    assert(dst[2] == 0);
+
+    memset(dst, 0, sizeof(dst));
+    swab(src, dst, 5);
+    assert(dst[0] == 0x02);
+    assert(dst[1] == 0x01);
+    assert(dst[2] == 0x04);
+    assert(dst[3] == 0x03);
+    assert(dst[4] == 0);
+    assert(dst[5] == 0);
+
+    return 0;
+}