Add HuCC SGX VDC scrolling example

examples/hucc/sgx_vdc_example/Makefile

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+all: sgx_vdc_scroll.sgx sgx_vdc_scroll.iso
+
+include ../Make_ex.inc
+
+SRC = sgx_vdc_scroll.c
+
+CFLAGS ?= -O2 --sgx -fno-recursive -gA
+CDFLAGS = --scd
+LIBS =
+
+sgx_vdc_scroll.iso: $(SRC)
+	$(CC) $(CFLAGS) $(CDFLAGS) $< $(LIBS)
+
+sgx_vdc_scroll.sgx: $(SRC) sgx_vdc_scroll.iso
+	$(CC) $(CFLAGS) $< $(LIBS)

examples/hucc/sgx_vdc_example/make.cmd

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+@rem ************************************************************************
+@rem ************************************************************************
+@rem
+@rem make.cmd
+@rem
+@rem Build a project with a native Windows version of Linux and macOS "make".
+@rem
+@rem Copyright John Brandwood 2025.
+@rem
+@rem Distributed under the Boost Software License, Version 1.0.
+@rem (See accompanying file LICENSE_1_0.txt or copy at
+@rem  http://www.boost.org/LICENSE_1_0.txt)
+@rem
+@rem ************************************************************************
+@rem ************************************************************************
+@rem
+@rem Put this in your project's directory on Windows to automatically set the
+@rem PATH and PCE_INCLUDE environment variables if your project is located in
+@rem a directory within the main HuC folder tree.
+@rem
+@rem Then mingw32-make.exe is run to build the project using its Makefile.
+@rem
+@rem You can run this from a Windows "Command Prompt", or by navigating to it
+@rem in Windows Explorer and then double-clicking on the file.
+@rem
+@rem ************************************************************************
+@rem ************************************************************************
+
+@echo off
+
+setlocal
+
+call :findexe hucc.exe
+if not [%EXEFILE%] == [""] goto :gotpath 
+
+cd /d "%~dp0"
+set rootdir="%~d0\"
+:search
+if not exist "%CD%\bin" goto :next
+if not exist "%CD%\bin\hucc.exe" goto :next
+set PATH=%CD%\bin;%PATH%
+set PCE_INCLUDE=%CD%\include\hucc
+goto :gotpath
+:next
+if not ["%CD%"] == [%rootdir%] (
+  cd ..
+  goto :search
+)
+echo.
+echo Unable to locate hucc.exe, please set up your PATH and PCE_INCLUDE
+echo environment variables!
+if /i "%comspec% /c %~0 " equ "%cmdcmdline:"=%" (
+  echo.
+  pause
+)
+exit /b 1
+
+:findexe
+set EXEFILE="%~$PATH:1"
+goto :eof
+
+:gotpath
+cd /d "%~dp0"
+mingw32-make.exe %*
+
+rem Pause if this was run by doubleclicking on the file in Explorer.
+if /i "%comspec% /c %~0 " equ "%cmdcmdline:"=%" (
+  echo.
+  pause
+)

examples/hucc/sgx_vdc_example/sgx_vdc_scroll.c

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+#include <huc.h>
+#include <hucc-scroll.h>
+
+/*
+ * DISPLAY CONTROL MACROS
+ * ------------------------
+ * These macros directly control the PC Engine (PCE) and SuperGrafx (SGX) displays
+ * by setting or clearing bits in their respective VDC control registers.
+ * They are implemented using inline assembly.
+ */
+void __fastcall __macro pce_disp_on(void);
+void __fastcall __macro pce_disp_off(void);
+void __fastcall __macro sgx_disp_on(void);
+void __fastcall __macro sgx_disp_off(void);
+
+#asm
+    .macro _pce_disp_on
+        lda    #$C0
+        tsb    <vdc_crl
+    .endm
+
+    .macro _pce_disp_off
+        lda    #$C0
+        trb    <vdc_crl
+    .endm
+
+    .macro _sgx_disp_on
+        lda    #$C0
+        tsb    <sgx_crl
+    .endm
+
+    .macro _sgx_disp_off
+        lda    #$C0
+        trb    <sgx_crl
+    .endm
+#endasm
+
+/*
+ * GRAPHICS ASSET LOADING
+ * -----------------------
+ * The following directives load the foreground (PC Engine) and background (SuperGrafx)
+ * assets from bitmap files. These include character (tile) data, palette data, and tile maps.
+ */
+
+/* Foreground graphics (PC Engine) */
+#incchr(f_chr, "f.bmp")
+#incpal(f_pal, "f.bmp")
+#incbat(f_bat, "f.bmp", 0x1000, 32, 32)
+
+/* Background graphics (SuperGrafx) */
+#incchr(b_chr, "b.bmp")
+#incpal(b_pal, "b.bmp")
+#incbat(b_bat, "b.bmp", 0x1000, 32, 32)
+
+main()
+{
+    unsigned char joyt;      /* Joystick trigger input */
+    unsigned char pce_on, sgx_on; /* Display state toggles: d_on for PCE, sd_on for SGX */
+    int scroll_x, scroll_y;  /* Fixed-point scroll positions (8-bit fractional part) */
+    int j;                   /* Loop counter (declared separately for C89 compliance) */
+
+    /* Temporary variables to extract integer scroll values */
+    unsigned char j_x, j_y;
+    int temp_x, temp_y;
+
+    /* Check for SGX hardware; if not present, display error and halt */
+    if (!sgx_detect())
+    {
+        put_string("ERROR: SGX hardware not found", 2, 13);
+        for (;;){}
+    }
+    /* If we pass we're on a SGX */
+    /* put_string("SGX hardware found", 12, 1); */
+
+    /* INITIALIZATION */
+    /* --------------- */
+    disp_off(); /* Turn off display while setting up */
+    sgx_disp_off(); /* Turn off display while setting up */
+    vsync();     /* Wait for vertical sync */
+
+    /* Setup PCE/SuperGrafx display, do this before loading anything or you will get a 64x32 BAT as a default for VDC1  */
+    set_screen_size(SCR_SIZE_32x32);
+    sgx_set_screen_size(SCR_SIZE_32x32);
+
+    /* Set font colors with a transparent background for text */
+    set_font_color(2, 0);
+    load_default_font();
+
+    /* Load the background scene (using foreground assets for demo purposes) */
+    load_background(f_chr, f_pal, f_bat, 32, 32);
+
+    /* Load VRAM for the background (SGX) layer and set the palette */
+    sgx_load_vram(0x0000, b_bat, 0x400);
+    sgx_load_vram(0x1000, b_chr, 0x5000);
+    //load_palette(0, b_pal, 16);
+
+    disp_on();
+    sgx_disp_on();  /* Enable the SGX display */
+
+    /* Display on-screen instructions and bakes them into the SGX layer by default */
+    put_string("VDC1 & VDC2 scrolling on SGX", 2, 1);
+    put_string(" I=Toggle VDC1 PCE layer", 6, 28);
+    put_string("II=Toggle VDC2 SGX layer", 6, 29);
+
+    /* Initialize display states and scroll positions */
+    pce_on = 1;
+    sgx_on = 1;
+    scroll_x = 0;
+    scroll_y = 0;
+
+    /* MAIN LOOP shows Sub-pixel scrolling and input handling */
+    for (;;)
+    {
+        /* Inner loop to gradually update the scroll position over 255 frames */
+        for (j = 0; j < 0xFF; j++)
+        {
+            vsync();  /* Synchronize with vertical refresh for smooth animation */
+
+            /*
+             * UPDATE SCROLL POSITION:
+             * Increment the fixed-point values by 4, which represents 1/8 of a pixel per frame.
+             * This allows for smooth sub-pixel scrolling.
+             */
+            scroll_x += 4;
+            scroll_y += 4;
+
+            /* Extract the integer part of the fixed-point scroll values */
+            temp_x = scroll_x >> 3;  /* Divide by 8 to remove the fractional part */
+            temp_y = scroll_y >> 3;
+            j_x = (unsigned char)temp_x;
+            j_y = (unsigned char)temp_y;
+
+            /*
+             * APPLY SCROLLING:
+             * - sgx_scroll_split() scrolls the SuperGrafx background layer.
+             * - scroll_split() scrolls the PC Engine layer, with a negative X offset for a parallax effect.
+             */
+            /* Background layer */
+            sgx_scroll_split(0, 0, j_x, j_y, sgx_on ? 0xC0 : 0x00);
+            /* Foreground layer */
+            scroll_split(0, 0, -j_x, -j_y, pce_on ? 0xC0 : 0x00);
+
+            /* HANDLE INPUT: Toggle display outputs when joystick buttons are pressed */
+            joyt = joytrg(0);
+            if (joyt & JOY_I)
+            {
+                pce_on = !pce_on;  /* Toggle PCE display flag */
+                if (pce_on)
+                    pce_disp_on();
+                else
+                    pce_disp_off();
+            }
+            if (joyt & JOY_II)
+            {
+                sgx_on = !sgx_on;  /* Toggle SGX display flag */
+                if (sgx_on)
+                    sgx_disp_on();
+                else
+                    sgx_disp_off();
+            }
+        }
+    }
+}

examples/hucc/sgx_vdc_example/sgx_vdc_scroll.cue

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+FILE sgx_vdc_scroll.iso BINARY
+  TRACK 01 MODE1/2048
+    INDEX 01 00:00:00