Impl scroll A static rendering

1 files changed, 8 insertions, 6 deletions

diff --git a/vdp.hpp b/vdp.hpp
index 71f259b..c239273 100644
--- a/vdp.hpp
+++ b/vdp.hpp
@@ -10,18 +10,19 @@
 
 class VDP {
     public:
-        VDP(const uint32_t base_address_a = VDP_START): base_address(base_address_a) {}
+        constexpr VDP(const uint32_t base_address_a = VDP_START): base_address(base_address_a) {}
         uint32_t Read(uint32_t offset, enum bitness);
         void Write(uint32_t offset, enum bitness, uint32_t value);
         bool Scanline(); // Returns true if display disabled or vblank happened
         void Reset();
-        const uint32_t* GetRenderedBuffer() const { return _rendered_buffer; }
+        constexpr const uint32_t* GetRenderedBuffer() const { return _rendered_buffer; }
 
         const uint32_t base_address;
 
-        static constexpr size_t render_height = 224;
-        static constexpr size_t render_width = 320;
-        static constexpr size_t render_buffer_size = 320*224*4;
+        static constexpr size_t kRenderHeight = 224;
+        static constexpr size_t kRenderWidth = 320;
+        static constexpr size_t render_buffer_size = kRenderWidth * kRenderHeight *
+            sizeof(*reinterpret_cast<VDP*>(4)->GetRenderedBuffer());
 
     private:
         struct StatusRegister {
@@ -70,6 +71,7 @@ class VDP {
             kRegistersCount, ///< Keep it last
         };
 
+        void renderScrollALine(size_t line_index, size_t hcell_count);
         void writeData(uint8_t address_mode, uint16_t address, uint16_t value);
         void writeControl(uint16_t value);
         uint16_t readData(uint8_t address_mode, uint16_t address);
@@ -112,5 +114,5 @@ class VDP {
         uint8_t _vram[kVRAMSize]{};
         uint8_t _cram[kCRAMSize]{};
         uint8_t _vsram[kVSRAMSize]{};
-        uint32_t _rendered_buffer[kLinesPerScreenNTSC * render_width]{};
+        uint32_t _rendered_buffer[kLinesPerScreenNTSC * kRenderWidth]{};
 };