Add big endian support

Co-authored-by: MookThompson <58513526+MookThompson@users.noreply.github.com>

.github/workflows/cmake.yml

@@ -68,6 +68,29 @@ jobs:
       shell: bash
       run: cmake --build . -j$(nproc)
 
+  build-linux-big-endian:
+    name: Linux (GCC) (Big Endian)
+    runs-on: ubuntu-20.04
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Build in container
+      uses: uraimo/run-on-arch-action@v2
+      with:
+        arch: s390x
+        distro: alpine_latest
+        githubToken: ${{ github.token }}
+        dockerRunArgs: |
+          --volume "${PWD}:/app"
+        env: |
+          LC_CTYPE: C.UTF-8
+        shell: /bin/sh
+        install: apk update && apk add make cmake g++ ncurses-dev gtest-dev linux-headers
+        run: |
+          cd /app
+          cmake . -DCMAKE_BUILD_TYPE=Debug -DTV_BUILD_USING_GPM=OFF -DTV_BUILD_APPS=OFF -DTV_BUILD_TESTS=ON -DTV_LIBRARY_UNITY_BUILD=ON
+          cmake --build . -j$(nproc)
+
   build-windows-msvc32:
     name: Windows (MSVC) (Win32)
     runs-on: windows-latest

examples/tvdemo/ascii.cpp

@@ -226,7 +226,7 @@ void TReport::handleEvent(TEvent& event)
         {
         if (event.message.command == cmAsciiTableCmdBase + cmCharFocused)
             {
-            asciiChar = event.message.infoByte;
+            asciiChar = (uchar)(size_t)event.message.infoPtr;
             drawView();
             }
         }

examples/tvdemo/tvdemo3.cpp

@@ -48,10 +48,12 @@ void TVDemo::mouse()
 
     if (mouseCage != 0)
         {
+        int32_t mouseReverse = TEventQueue::mouseReverse;
         mouseCage->helpCtx = hcOMMouseDBox;
-        mouseCage->setData(&(TEventQueue::mouseReverse));
+        mouseCage->setData(&mouseReverse);
         if (deskTop->execView(mouseCage) != cmCancel)
-            mouseCage->getData(&(TEventQueue::mouseReverse));
+            mouseCage->getData(&mouseReverse);
+        TEventQueue::mouseReverse = mouseReverse;
         }
     destroy( mouseCage );
 

include/tvision/colors.h

@@ -57,20 +57,34 @@ inline TColorAttr reverseAttribute(TColorAttr attr)
 struct TColorRGB
 {
     uint32_t
+#ifndef TV_BIG_ENDIAN
         b       : 8,
         g       : 8,
         r       : 8,
         _unused : 8;
+#else
+        _unused : 8,
+        r       : 8,
+        g       : 8,
+        b       : 8;
+#endif
 
     TV_TRIVIALLY_CONVERTIBLE(TColorRGB, uint32_t, 0xFFFFFF)
     constexpr inline TColorRGB(uint8_t r, uint8_t g, uint8_t b);
 };
 
 constexpr inline TColorRGB::TColorRGB(uint8_t r, uint8_t g, uint8_t b) :
+#ifndef TV_BIG_ENDIAN
     b(b),
     g(g),
     r(r),
     _unused(0)
+#else
+    _unused(0),
+    r(r),
+    g(g),
+    b(b)
+#endif
 {
 }
 
@@ -90,11 +104,19 @@ constexpr inline TColorRGB::TColorRGB(uint8_t r, uint8_t g, uint8_t b) :
 struct TColorBIOS
 {
     uint8_t
+#ifndef TV_BIG_ENDIAN
         b       : 1,
         g       : 1,
         r       : 1,
         bright  : 1,
         _unused : 4;
+#else
+        _unused : 4,
+        bright  : 1,
+        r       : 1,
+        g       : 1,
+        b       : 1;
+#endif
 
     TV_TRIVIALLY_CONVERTIBLE(TColorBIOS, uint8_t, 0xF)
 };

include/tvision/internal/ansidisp.h

@@ -5,6 +5,7 @@
 #include <tvision/tv.h>
 
 #include <internal/termdisp.h>
+#include <internal/endian.h>
 
 namespace tvision
 {
@@ -30,6 +31,9 @@ struct TermColor
 
     TermColor& operator=(uint32_t val) noexcept
     {
+#ifdef TV_BIG_ENDIAN
+        reverseBytes(val);
+#endif
         memcpy(this, &val, sizeof(*this));
         return *this;
         static_assert(sizeof(*this) == 4, "");
@@ -38,6 +42,9 @@ struct TermColor
     {
         uint32_t val;
         memcpy(&val, this, sizeof(*this));
+#ifdef TV_BIG_ENDIAN
+        reverseBytes(val);
+#endif
         return val;
     }
     TermColor(uint8_t aIdx, TermColorTypes aType) noexcept

include/tvision/internal/endian.h

@@ -0,0 +1,29 @@
+#ifndef TVISION_ENDIAN_H
+#define TVISION_ENDIAN_H
+
+#include <stdint.h>
+
+namespace tvision
+{
+
+inline void reverseBytes(uint16_t &val)
+{
+    val = (val << 8) | (val >> 8);
+}
+
+inline void reverseBytes(uint32_t &val)
+{
+    val = ((val << 8) & 0xFF00FF00U) | ((val >> 8) & 0x00FF00FF);
+    val = (val << 16) | (val >> 16);
+}
+
+inline void reverseBytes(uint64_t &val)
+{
+    val = ((val << 8) & 0xFF00FF00FF00FF00ULL) | ((val >> 8) & 0x00FF00FF00FF00FFULL);
+    val = ((val << 16) & 0xFFFF0000FFFF0000ULL) | ((val >> 16) & 0x0000FFFF0000FFFFULL);
+    val = (val << 32) | (val >> 32);
+}
+
+} // namespace tvision
+
+#endif // TVISION_ENDIAN_H

include/tvision/internal/strings.h

@@ -1,19 +1,17 @@
 #ifndef TVISION_STRINGS_H
 #define TVISION_STRINGS_H
 
-#ifndef _TV_VERSION
 #include <tvision/tv.h>
-#endif
 
 namespace tvision
 {
 
 template<class Int>
 inline constexpr Int string_as_int(TStringView s) noexcept
+// CAUTION: It is not endian-safe to reinterpret the result as an array of bytes.
 {
     Int res = 0;
     for (size_t i = 0; i < min(s.size(), sizeof(res)); ++i)
-        // CAUTION: Assumes Little Endian.
         res |= uint64_t(uint8_t(s[i])) << 8*i;
     return res;
 }
@@ -32,15 +30,15 @@ struct alignas(4) btoa_lut_elem_t
 using btoa_lut_t = constarray<btoa_lut_elem_t, 256>;
 
 inline char *fast_btoa(uint8_t value, char *buffer) noexcept
+// Pre: the capacity of 'buffer' is at least 4 bytes.
 {
     extern const btoa_lut_t btoa_lut;
     const auto &lut = (btoa_lut_elem_t (&) [256]) btoa_lut;
-    // 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);
+    // Optimization: read and write the whole LUT entry at once in order to
+    // minimize memory accesses. We can afford to write more bytes into 'buffer'
+    // than digits.
+    memcpy(buffer, &lut[value], 4);
+    return buffer + (uint8_t) buffer[3];
     static_assert(sizeof(btoa_lut_elem_t) == 4, "");
 }
 

include/tvision/internal/utf8.h

@@ -1,7 +1,9 @@
 #ifndef TVISION_UTF8_H
 #define TVISION_UTF8_H
 
-#include <internal/strings.h>
+#include <tvision/tv.h>
+
+#include <internal/endian.h>
 
 #include <stdint.h>
 #include <string.h>
@@ -66,6 +68,9 @@ inline size_t utf32To8(uint32_t u32, char u8[4]) noexcept
             (( u32        & 0b00111111) | 0b10000000) << 24;
         length = 4;
     }
+#ifdef TV_BIG_ENDIAN
+    reverseBytes(asInt);
+#endif
     memcpy(u8, &asInt, 4);
     return length;
 }

include/tvision/scrncell.h

@@ -76,13 +76,14 @@ struct TCellChar
 
 inline void TCellChar::moveChar(char ch)
 {
-    moveInt((uchar) ch);
+    memset(this, 0, sizeof(*this));
+    _text[0] = ch;
 }
 
 inline void TCellChar::moveInt(uint32_t mbc, bool wide)
+// Pre: 'mbc' is a bit-casted multibyte-encoded character.
 {
     memset(this, 0, sizeof(*this));
-    // CAUTION: Assumes Little Endian.
     memcpy(_text, &mbc, sizeof(mbc));
     _flags = -int(wide) & fWide;
 }

include/tvision/system.h

@@ -187,8 +187,13 @@ inline void TMouse::registerHandler( unsigned mask, void (_FAR *func)() )
 
 struct CharScanType
 {
+#if !defined( TV_BIG_ENDIAN )
     uchar charCode;
     uchar scanCode;
+#else
+    uchar scanCode;
+    uchar charCode;
+#endif
 };
 
 struct KeyDownEvent

source/CMakeLists.txt

@@ -74,6 +74,17 @@ target_compile_definitions(${PROJECT_NAME} PRIVATE
     TVISION_NO_STL
 )
 
+include(TestBigEndian)
+
+TEST_BIG_ENDIAN(IS_BIG_ENDIAN)
+
+if (IS_BIG_ENDIAN)
+    tv_message(STATUS "Big endian system detected")
+    target_compile_definitions(${PROJECT_NAME} PUBLIC
+        TV_BIG_ENDIAN
+    )
+endif()
+
 # Dependencies
 
 if (NOT WIN32)

source/platform/ansidisp.cpp

@@ -156,9 +156,13 @@ struct alignas(8) colorconv_r
     uint8_t unused[2];
 
     colorconv_r() = default;
-    colorconv_r(TermColor aColor, TColorAttr::Style aExtraFlags=0) noexcept
+    colorconv_r(TermColor aColor, TColorAttr::Style aExtraFlags = 0) noexcept
     {
+        // Optimization: do bit-casting manually, just like with TermColor.
         uint64_t val = aColor | (uint64_t(aExtraFlags) << 32);
+#ifdef TV_BIG_ENDIAN
+        reverseBytes(val);
+#endif
         memcpy(this, &val, 8);
         static_assert(sizeof(*this) == 8, "");
     }

source/platform/buffdisp.cpp

@@ -340,7 +340,7 @@ inline void FlushScreenAlgorithm::writeCell() noexcept
 inline void FlushScreenAlgorithm::writeSpace() noexcept
 {
     TCellChar ch;
-    ch.moveInt(' ');
+    ch.moveChar(' ');
     writeCell(ch, cell->attr, 0);
 }
 

source/platform/far2l.cpp

@@ -6,6 +6,7 @@
 #include <internal/constmap.h>
 #include <internal/base64.h>
 #include <internal/events.h>
+#include <internal/endian.h>
 
 #include <time.h>
 
@@ -97,6 +98,16 @@ ParseResult parseFar2lInput(GetChBuf &buf, TEvent &ev, InputState &state) noexce
             memcpy(&kev.dwControlKeyState, &out[6],  4);
             memcpy(&kev.uChar.UnicodeChar, &out[10], 4);
 
+#ifdef TV_BIG_ENDIAN
+            // The protocol states that "all integer values are in
+            // little-endian format", so convert them.
+            reverseBytes(kev.wRepeatCount);
+            reverseBytes(kev.wVirtualKeyCode);
+            reverseBytes(kev.wVirtualScanCode);
+            reverseBytes(kev.dwControlKeyState);
+            reverseBytes((uint32_t &) kev.uChar.UnicodeChar);
+#endif
+
             if (uint16_t keyCode = virtualKeyCodeToKeyCode[kev.wVirtualKeyCode])
             {
                 kev.wVirtualScanCode = keyCode >> 8;
@@ -120,6 +131,14 @@ ParseResult parseFar2lInput(GetChBuf &buf, TEvent &ev, InputState &state) noexce
             memcpy(&mev.dwControlKeyState, &out[8],  4);
             memcpy(&mev.dwEventFlags,      &out[12], 4);
 
+#ifdef TV_BIG_ENDIAN
+            reverseBytes((uint16_t &) mev.dwMousePosition.X);
+            reverseBytes((uint16_t &) mev.dwMousePosition.Y);
+            reverseBytes(mev.dwButtonState);
+            reverseBytes(mev.dwControlKeyState);
+            reverseBytes(mev.dwEventFlags);
+#endif
+
             getWin32Mouse(mev, ev, state);
             return Accepted;
         }

source/platform/win32con.cpp

@@ -413,7 +413,7 @@ bool getWin32Key(const KEY_EVENT_RECORD &KeyEvent, TEvent &ev, InputState &state
 
     ev.what = evKeyDown;
     ev.keyDown.charScan.scanCode = KeyEvent.wVirtualScanCode;
-    ev.keyDown.charScan.charCode = KeyEvent.uChar.AsciiChar;
+    ev.keyDown.charScan.charCode = (uchar) KeyEvent.uChar.UnicodeChar;
     ev.keyDown.controlKeyState = KeyEvent.dwControlKeyState & (
         kbShift | kbCtrlShift | kbAltShift |
         kbScrollState | kbNumState | kbCapsState | kbEnhanced