Add strchr.

Author: thejpster

README.md

@@ -15,6 +15,7 @@ This crate basically came about so that the [nrfxlib](https://github.com/NordicP
 * strlen
 * strtol
 * strstr
+* strchr
 * snprintf
 * vsnprintf
 

rustfmt.toml

@@ -0,0 +1,2 @@
+hard_tabs = false
+

src/lib.rs

@@ -28,6 +28,9 @@ pub use self::strtol::strtol;
 mod strstr;
 pub use self::strstr::strstr;
 
+mod strchr;
+pub use self::strchr::strchr;
+
 mod atoi;
 pub use self::atoi::atoi;
 

src/strchr.rs

@@ -0,0 +1,61 @@
+//! Rust implementation of C library function `strchr`
+//!
+//! Copyright (c) 42 Technology Ltd
+//! Licensed under the Blue Oak Model Licence 1.0.0
+
+use crate::{CChar, CInt};
+
+/// Rust implementation of C library function `strchr`
+#[no_mangle]
+pub unsafe extern "C" fn strchr(haystack: *const CChar, needle: CInt) -> *const CChar {
+    for idx in 0.. {
+        let ptr = haystack.offset(idx);
+        if needle == (*ptr) as i32 {
+            return ptr;
+        }
+        if (*ptr) == 0 {
+            break;
+        }
+    }
+    core::ptr::null()
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn no_match() {
+        let haystack = b"haystack\0".as_ptr();
+        let result = unsafe { strchr(haystack, b'X' as CInt) };
+        assert_eq!(result, core::ptr::null());
+    }
+
+    #[test]
+    fn null() {
+        let haystack = b"haystack\0".as_ptr();
+        let result = unsafe { strchr(haystack, 0) };
+        assert_eq!(result, unsafe { haystack.offset(8) });
+    }
+
+    #[test]
+    fn start() {
+        let haystack = b"haystack\0".as_ptr();
+        let result = unsafe { strchr(haystack, b'h' as CInt) };
+        assert_eq!(result, haystack);
+    }
+
+    #[test]
+    fn middle() {
+        let haystack = b"haystack\0".as_ptr();
+        let result = unsafe { strchr(haystack, b'y' as CInt) };
+        assert_eq!(result, unsafe { haystack.offset(2) });
+    }
+
+    #[test]
+    fn end() {
+        let haystack = b"haystack\0".as_ptr();
+        let result = unsafe { strchr(haystack, b'k' as CInt) };
+        assert_eq!(result, unsafe { haystack.offset(7) });
+    }
+}

src/strlen.rs

@@ -34,5 +34,4 @@ mod test {
     fn test3() {
         assert_eq!(unsafe { strlen(b"X\0" as *const CChar) }, 1);
     }
-
 }