Port hex_string_to_int from C to Rust and support uppercase hex (#2141)

Author: Anayo-Anyafulu

src/lib_ccx/utility.c

@@ -269,6 +269,13 @@ void sleep_secs(int secs)
 #endif
 }
 
+#ifndef DISABLE_RUST
+extern int ccxr_hex_to_int(char high, char low);
+int hex_to_int(char high, char low)
+{
+	return ccxr_hex_to_int(high, low);
+}
+#else
 int hex_to_int(char high, char low)
 {
 	unsigned char h, l;
@@ -286,6 +293,15 @@ int hex_to_int(char high, char low)
 		return -1;
 	return h * 16 + l;
 }
+#endif
+
+#ifndef DISABLE_RUST
+extern int ccxr_hex_string_to_int(const char *string, int len);
+int hex_string_to_int(char *string, int len)
+{
+	return ccxr_hex_string_to_int(string, len);
+}
+#else
 int hex_string_to_int(char *string, int len)
 {
 	int total_return = 0;
@@ -302,6 +318,7 @@ int hex_string_to_int(char *string, int len)
 	}
 	return total_return;
 }
+#endif
 
 #ifndef _WIN32
 void m_signal(int sig, void (*func)(int))

src/rust/lib_ccxr/src/util/hex.rs

@@ -0,0 +1,51 @@
+/// Converts a single hex character to its integer value.
+/// Returns None if the character is not valid (0-9, a-f, or A-F).
+fn hex_char_to_val(c: char) -> Option<i32> {
+    match c {
+        '0'..='9' => Some(c as i32 - '0' as i32),
+        'a'..='f' => Some(c as i32 - 'a' as i32 + 10),
+        'A'..='F' => Some(c as i32 - 'A' as i32 + 10),
+        _ => None,
+    }
+}
+
+/// Converts two hex characters into a combined integer value.
+/// Returns None if either character is invalid.
+pub fn hex_to_int(high: char, low: char) -> Option<i32> {
+    let h = hex_char_to_val(high)?;
+    let l = hex_char_to_val(low)?;
+    Some(h * 16 + l)
+}
+
+pub fn hex_string_to_int(string: &str, len: usize) -> Option<i32> {
+    let mut result = 0;
+    for c in string.chars().take(len) {
+        result = result * 16 + hex_char_to_val(c)?;
+    }
+    Some(result)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_hex_to_int() {
+        assert_eq!(hex_to_int('4', 'f'), Some(79));
+        assert_eq!(hex_to_int('0', '0'), Some(0));
+        assert_eq!(hex_to_int('f', 'f'), Some(255));
+        assert_eq!(hex_to_int('A', 'F'), Some(175));
+        assert_eq!(hex_to_int('z', '1'), None);
+    }
+
+    #[test]
+    fn test_hex_string_to_int() {
+        assert_eq!(hex_string_to_int("4f", 2), Some(79));
+        assert_eq!(hex_string_to_int("ff", 2), Some(255));
+        assert_eq!(hex_string_to_int("00", 2), Some(0));
+        assert_eq!(hex_string_to_int("ffff", 4), Some(65535));
+        assert_eq!(hex_string_to_int("4f", 1), Some(4));
+        assert_eq!(hex_string_to_int("FF", 2), Some(255));
+        assert_eq!(hex_string_to_int("zz", 2), None);
+    }
+}

src/rust/lib_ccxr/src/util/mod.rs

@@ -13,6 +13,7 @@
 pub mod bits;
 pub mod encoders_helper;
 pub mod encoding;
+pub mod hex;
 pub mod levenshtein;
 pub mod log;
 pub mod time;

src/rust/src/libccxr_exports/mod.rs

@@ -129,3 +129,4 @@ pub unsafe extern "C" fn ccxr_levenshtein_dist_char(
 
     ans.min(c_int::MAX as usize) as c_int
 }
+pub mod util;

src/rust/src/libccxr_exports/util.rs

@@ -0,0 +1,27 @@
+use std::ffi::{c_char, c_int};
+
+/// Rust equivalent for `hex_to_int` function in C. Uses C-native types as input and output.
+///
+/// # Safety
+///
+/// `high` and `low` must be valid ASCII characters. Invalid characters will
+/// return -1 rather than causing undefined behavior.
+#[no_mangle]
+pub unsafe extern "C" fn ccxr_hex_to_int(high: c_char, low: c_char) -> c_int {
+    lib_ccxr::util::hex::hex_to_int(high as u8 as char, low as u8 as char).unwrap_or(-1)
+}
+
+/// Rust equivalent for `hex_string_to_int` function in C. Uses C-native types as input and output.
+///
+/// # Safety
+///
+/// `string` must be a valid null-terminated C string. If null, returns -1.
+/// Invalid hex characters will return -1 rather than causing undefined behavior.
+#[no_mangle]
+pub unsafe extern "C" fn ccxr_hex_string_to_int(string: *const c_char, len: c_int) -> c_int {
+    if string.is_null() {
+        return -1;
+    }
+    let s = std::ffi::CStr::from_ptr(string).to_str().unwrap_or("");
+    lib_ccxr::util::hex::hex_string_to_int(s, len as usize).unwrap_or(-1)
+}