Support Big Endian Linux platform (z/Linux)

CMakeLists.txt

@@ -160,6 +160,17 @@ endif()
 
 option(TV_BUILD_TESTS "Build and run tests" OFF)
 
+# Endianness detection
+
+include(TestBigEndian)
+TEST_BIG_ENDIAN(BIGENDIAN)
+if(${BIGENDIAN})
+    add_definitions(-DTV_BIG_ENDIAN)
+    tv_message_mp(STATUS "BIG ENDIAN platform detected")
+else()
+    tv_message_mp(STATUS "LITTLE ENDIAN platform detected")
+endif(${BIGENDIAN})
+
 # Library
 
 add_subdirectory(source)

include/tvision/internal/ansidisp.h

@@ -30,14 +30,14 @@ struct TermColor
 
     TermColor& operator=(uint32_t val) noexcept
     {
-        memcpy(this, &val, sizeof(*this));
+        tvintmemcpy(this, &val, sizeof(*this));
         return *this;
         static_assert(sizeof(*this) == 4, "");
     }
     operator uint32_t() const noexcept
     {
         uint32_t val;
-        memcpy(&val, this, sizeof(*this));
+        tvintmemcpy(&val, this, sizeof(*this));
         return val;
     }
     TermColor(uint8_t aIdx, TermColorTypes aType) noexcept

include/tvision/internal/codepage.h

@@ -23,7 +23,7 @@ class CpTranslator
     static uint32_t toPackedUtf8(unsigned char c) noexcept
     {
         uint32_t asInt;
-        memcpy(&asInt, (*currentToUtf8)[c], sizeof(asInt));
+        tvintmemcpy(&asInt, (*currentToUtf8)[c], sizeof(asInt));
         return asInt;
     }
 

include/tvision/internal/strings.h

@@ -13,8 +13,12 @@ inline constexpr Int string_as_int(TStringView s) noexcept
 {
     Int res = 0;
     for (size_t i = 0; i < min(s.size(), sizeof(res)); ++i)
+#ifndef TV_BIG_ENDIAN
         // CAUTION: Assumes Little Endian.
         res |= uint64_t(uint8_t(s[i])) << 8*i;
+#else
+        res |= uint64_t(uint8_t(s[i])) << 8*(sizeof(res)-1-i);
+#endif
     return res;
 }
 
@@ -35,13 +39,19 @@ inline char *fast_btoa(uint8_t value, char *buffer) noexcept
 {
     extern const btoa_lut_t btoa_lut;
     const auto &lut = (btoa_lut_elem_t (&) [256]) btoa_lut;
+#ifndef TV_BIG_ENDIAN
     // CAUTION: Assumes Little Endian.
     // We can afford to write more bytes into 'buffer' than digits.
     uint32_t asInt;
     memcpy(&asInt, &lut[value], 4);
     memcpy(buffer, &asInt, 4);
     return buffer + (asInt >> 24);
     static_assert(sizeof(btoa_lut_elem_t) == 4, "");
+#else
+    memcpy(buffer, &lut[value].chars, lut[value].digits);
+    buffer[lut[value].digits] = 0;  // null-terminate for safety - may not be needed?
+    return buffer + lut[value].digits;
+#endif
 }
 
 } // namespace tvision

include/tvision/internal/utf8.h

@@ -66,7 +66,7 @@ inline size_t utf32To8(uint32_t u32, char u8[4]) noexcept
             (( u32        & 0b00111111) | 0b10000000) << 24;
         length = 4;
     }
-    memcpy(u8, &asInt, 4);
+    tvintmemcpy(u8, &asInt, 4);
     return length;
 }
 

include/tvision/scrncell.h

@@ -83,7 +83,7 @@ inline void TCellChar::moveInt(uint32_t mbc, bool wide)
 {
     memset(this, 0, sizeof(*this));
     // CAUTION: Assumes Little Endian.
-    memcpy(_text, &mbc, sizeof(mbc));
+    tvintmemcpy(_text, &mbc, sizeof(mbc));
     _flags = -int(wide) & fWide;
 }
 

include/tvision/system.h

@@ -187,8 +187,14 @@ inline void TMouse::registerHandler( unsigned mask, void (_FAR *func)() )
 
 struct CharScanType
 {
+#ifndef TV_BIG_ENDIAN
     uchar charCode;
     uchar scanCode;
+#else
+    // big endian version reverses the order
+    uchar scanCode;
+    uchar charCode;
+#endif
 };
 
 struct KeyDownEvent

include/tvision/util.h

@@ -110,4 +110,21 @@ char *ultoa( ulong value, char *buffer, int radix ) noexcept;
 
 #endif // __BORLANDC__
 
+#ifdef TV_BIG_ENDIAN
+    inline void *be_tvintmemcpy(void *dest, const void *src, size_t n)  // implementation of tvintmemcpy for Big Endian platforms, reverses bytes while copying
+    {
+        // TVision assumes Little Endian byte order for some operations where uints are assigned to stucts etc.
+        // This memcpy-like function reverses the order of the bytes when copying them, so can be used on big-endian
+        // platforms in place of a standard memcpy.
+        for (size_t i=0; i<n; i++) {
+            ((uchar*)dest)[i] = ((const uchar*)src)[n-i-1];
+        }
+        return dest;
+    }
+    #define tvintmemcpy be_tvintmemcpy
+#else
+    // On little-endian platforms, just use memcpy as before
+    #define tvintmemcpy memcpy
+#endif
+
 #endif  // __UTIL_H

source/platform/ansidisp.cpp

@@ -159,7 +159,7 @@ struct alignas(8) colorconv_r
     colorconv_r(TermColor aColor, TColorAttr::Style aExtraFlags=0) noexcept
     {
         uint64_t val = aColor | (uint64_t(aExtraFlags) << 32);
-        memcpy(this, &val, 8);
+        tvintmemcpy(this, &val, 8);
         static_assert(sizeof(*this) == 8, "");
     }
 };