Improve syntax and do trivial cleanup

Author: ckormanyos

ref_app/target/micros/xtensa_esp32_s3/startup/Std/StdLib.cpp

@@ -29,108 +29,6 @@
 
 extern "C" {
 
-typedef   signed long long DItype  __attribute__((mode (DI)));
-typedef unsigned long long UDItype __attribute__((mode (DI)));
-typedef unsigned int       USItype __attribute__((mode (SI)));
-
-extern int __builtin_clzll(unsigned long long);
-
-#define DWtype  DItype
-#define UDWtype UDItype
-#define UWtype  USItype
-
-UDWtype __udivdi3    (UDWtype n, UDWtype d);
-UDWtype __udivmoddi4 (UDWtype n, UDWtype d, UDWtype *rp);
-UDWtype __umoddi3    (UDWtype u, UDWtype v);
-
-UDWtype __udivdi3 (UDWtype n, UDWtype d)
-{
-  return __udivmoddi4 (n, d, (UDWtype *) 0);
-}
-
-UDWtype __umoddi3 (UDWtype u, UDWtype v)
-{
-  UDWtype w;
-
-  (void) __udivmoddi4 (u, v, &w);
-
-  return w;
-}
-
-UDWtype __udivmoddi4 (UDWtype n, UDWtype d, UDWtype *rp)
-{
-  UDWtype q = 0, r = n, y = d;
-  UWtype lz1, lz2, i, k;
-
-  // Implements align divisor shift dividend method. This algorithm
-  // aligns the divisor under the dividend and then perform number of
-  // test-subtract iterations which shift the dividend left. Number of
-  // iterations is k + 1 where k is the number of bit positions the
-  // divisor must be shifted left to align it under the dividend.
-  // quotient bits can be saved in the rightmost positions of the dividend
-  // as it shifts left on each test-subtract iteration.
-
-  if (y <= r)
-  {
-    lz1 = static_cast<USItype>(__builtin_clzll(static_cast<unsigned long long>(d)));
-    lz2 = static_cast<USItype>(__builtin_clzll(static_cast<unsigned long long>(n)));
-
-    k = lz1 - lz2;
-    y = (y << k);
-
-    // Dividend can exceed 2 ^ (width - 1) - 1 but still be less than the
-    // aligned divisor. Normal iteration can drops the high order bit
-    // of the dividend. Therefore, first test-subtract iteration is a
-    // special case, saving its quotient bit in a separate location and
-    // not shifting the dividend.
-
-    if (r >= y)
-    {
-      r = r - y;
-      q =  (1ULL << k);
-    }
-    
-    if (k > 0)
-    {
-      y = y >> 1;
-
-      // k additional iterations where k regular test subtract shift
-      // dividend iterations are done.
-
-      i = k;
-
-      do
-      {
-        if (r >= y)
-        {
-          r = ((r - y) << 1) + 1;
-        }
-        else
-        {
-          r =  (r << 1);
-        }
-
-        i = i - 1;
-      }
-      while (i != 0);
-
-      // First quotient bit is combined with the quotient bits resulting
-      // from the k regular iterations.
-
-      q = q + r;
-      r = r >> k;
-      q = q - (r << k);
-    }
-  }
-
-  if (rp)
-  {
-    *rp = r;
-  }
-
-  return q;
-}
-
 #if defined(__GNUC__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wcast-align"
@@ -186,7 +84,8 @@ void* memcpy (void* dest, const void* src, size_t n)
   const std::uint8_t* s { reinterpret_cast<const uint8_t*>(src) };
 
   // Align destination to the next 32-bit boundary.
-  while (((uintptr_t) d & 3) && n > 0)
+  while (   (static_cast<unsigned>(reinterpret_cast<std::uintptr_t>(d) & unsigned { UINT8_C(3) }) != 0U)
+         && (n > std::size_t { UINT8_C(0) }))
   {
     *d++ = *s++;
 
@@ -198,19 +97,19 @@ void* memcpy (void* dest, const void* src, size_t n)
         std::uint32_t* d32 { reinterpret_cast<std::uint32_t*>(d) };
   const std::uint32_t* s32 { reinterpret_cast<const uint32_t*>(s) };
 
-  while (n >= 4)
+  while (n >= std::size_t { UINT8_C(4) })
   {
     *d32++ = *s32++;
 
-    n -= 4;
+    n -= std::size_t { UINT8_C(4) };
   }
 
   // Handle any remaining bytes.
 
   d = reinterpret_cast<std::uint8_t*>(d32);
   s = reinterpret_cast<const uint8_t*>(s32);
 
-  while (n > 0)
+  while (n > std::size_t { UINT8_C(0) })
   {
     *d++ = *s++;