fn ZDICT_fillNoise: make safe

Author: folkertdev

lib/dictBuilder/zdict.rs

@@ -716,18 +716,19 @@ unsafe fn ZDICT_trainBuffer_legacy(
     free(filePos as *mut core::ffi::c_void);
     result
 }
-unsafe fn ZDICT_fillNoise(buffer: *mut core::ffi::c_void, length: size_t) {
-    let prime1 = 2654435761 as core::ffi::c_uint;
-    let prime2 = 2246822519 as core::ffi::c_uint;
+
+fn fill_noise(buffer: &mut [u8]) {
+    const prime1: u32 = 2654435761;
+    const prime2: u32 = 2246822519;
+
     let mut acc = prime1;
-    let mut p = 0;
-    p = 0;
-    while p < length {
+
+    for v in buffer.iter_mut() {
         acc = acc.wrapping_mul(prime2);
-        *(buffer as *mut core::ffi::c_uchar).add(p) = (acc >> 21) as core::ffi::c_uchar;
-        p = p.wrapping_add(1);
+        *v = (acc >> 21) as u8;
     }
 }
+
 const MAXREPOFFSET: core::ffi::c_int = 1024;
 unsafe fn ZDICT_countEStats(
     esr: EStats_ress_t,
@@ -1606,10 +1607,12 @@ pub unsafe extern "C" fn ZDICT_trainFromBuffer_legacy(
         return Error::memory_allocation.to_error_code();
     }
     memcpy(newBuff, samplesBuffer, sBuffSize);
-    ZDICT_fillNoise(
-        (newBuff as *mut core::ffi::c_char).add(sBuffSize) as *mut core::ffi::c_void,
+
+    fill_noise(core::slice::from_raw_parts_mut(
+        newBuff.cast::<u8>().byte_add(sBuffSize),
         NOISELENGTH as size_t,
-    );
+    ));
+
     result = ZDICT_trainFromBuffer_unsafe_legacy(
         dictBuffer,
         dictBufferCapacity,
@@ -1714,7 +1717,7 @@ mod test {
     #[test]
     fn test_fill_noise() {
         let mut buf = vec![0u8; 16];
-        unsafe { ZDICT_fillNoise(buf.as_mut_ptr().cast(), buf.len()) };
+        fill_noise(&mut buf);
         assert_eq!(
             buf,
             [226, 51, 247, 105, 221, 225, 137, 112, 5, 188, 15, 79, 183, 243, 110, 209]