Add DOS HAL backend and OpenWatcom build for FreeDOS

platform/hal_dos.c: DOS HAL implementation using BIOS INT 10h for screen/cursor, INT 16h for keyboard, direct character output via BIOS write-char. Compile-time selection via __MSDOS__ define. Linux HAL (hal_posix.c) unchanged -- full backward compatibility. hal.h: add hal_dos_create() declaration under __MSDOS__ guard. main.c, gwrt.c: select HAL at compile time via #ifdef __MSDOS__. Makefile.dos: OpenWatcom wmake build file targeting DOS/4GW 32-bit. Builds GWBASIC.EXE (interpreter), GWBASCOM.EXE (compiler), GWRT.LIB (runtime library for compiled programs). All 72 interpreter, 14 kernel, and 69 compiler tests continue to pass on Linux (no regression).
2026-03-30 18:12:24 -04:00
parent 15af9ad12c
commit d1a58876e7
5 changed files with 283 additions and 0 deletions
@@ -0,0 +1,59 @@
+# Makefile for building GW-BASIC 2026 with OpenWatcom for DOS
+#
+# Usage:
+#   wmake -f Makefile.dos           (from OpenWatcom environment)
+#   wmake -f Makefile.dos clean
+#
+# Requires: OpenWatcom 2.0+ with DOS/4GW 32-bit target
+# Produces: GWBASIC.EXE (interpreter), GWBASCOM.EXE (compiler), GWRT.LIB (runtime)
+
+CC = wcc386
+CFLAGS = -bt=dos -mf -ox -w4 -zq -Iinclude -D__MSDOS__
+LINKER = wlink
+LIBRARIAN = wlib
+
+# Interpreter sources (excludes compiler_main, analysis, codegen, gwrt)
+INTERP_OBJS = &
+    src/main.obj src/tokens.obj src/tokenizer.obj src/error.obj &
+    src/eval.obj src/interp.obj src/vars.obj src/arrays.obj &
+    src/input.obj src/math_int.obj src/math_float.obj &
+    src/math_transcend.obj src/strings.obj src/print.obj &
+    src/fileio.obj src/program_io.obj src/print_using.obj &
+    src/graphics.obj src/virmem.obj src/portio.obj src/strpool.obj &
+    src/sound.obj src/tui.obj platform/hal_dos.obj
+
+# Runtime library (for compiled programs)
+GWRT_OBJS = &
+    src/tokens.obj src/tokenizer.obj src/error.obj &
+    src/eval.obj src/interp.obj src/vars.obj src/arrays.obj &
+    src/input.obj src/math_int.obj src/math_float.obj &
+    src/math_transcend.obj src/strings.obj src/print.obj &
+    src/fileio.obj src/program_io.obj src/print_using.obj &
+    src/graphics.obj src/virmem.obj src/portio.obj src/strpool.obj &
+    src/sound.obj src/tui.obj src/gwrt.obj platform/hal_dos.obj
+
+# Compiler sources
+COMP_OBJS = &
+    src/compiler_main.obj src/analysis.obj src/codegen.obj &
+    src/tokens.obj src/tokenizer.obj
+
+.c.obj:
+    $(CC) $(CFLAGS) -fo=$@ $<
+
+all: gwbasic.exe gwbascom.exe gwrt.lib
+
+gwbasic.exe: $(INTERP_OBJS)
+    $(LINKER) system dos4g name $@ file { $< }
+
+gwrt.lib: $(GWRT_OBJS)
+    $(LIBRARIAN) -q -n $@ $(GWRT_OBJS)
+
+gwbascom.exe: $(COMP_OBJS)
+    $(LINKER) system dos4g name $@ file { $< }
+
+clean: .SYMBOLIC
+    del src\*.obj
+    del platform\*.obj
+    del gwbasic.exe
+    del gwbascom.exe
+    del gwrt.lib
@@ -38,5 +38,8 @@ extern hal_ops_t *gw_hal;

 /* Platform implementations */
 hal_ops_t *hal_posix_create(void);
+#ifdef __MSDOS__
+hal_ops_t *hal_dos_create(void);
+#endif

 #endif
@@ -0,0 +1,213 @@
+/*
+ * DOS HAL backend for GW-BASIC 2026.
+ *
+ * Uses BIOS/DOS interrupts for terminal I/O, keyboard input,
+ * and screen control.  Replaces the POSIX HAL (hal_posix.c)
+ * when targeting FreeDOS or other DOS-compatible systems.
+ *
+ * Build with OpenWatcom:  wcl386 -bt=dos -l=dos4g ...
+ * Build with DJGPP:       gcc -o gwbasic.exe ...
+ *
+ * Linux compatibility is retained -- hal_posix.c is used on
+ * POSIX systems, hal_dos.c on DOS.  The hal_ops_t vtable
+ * provides the compile-time abstraction.
+ */
+
+#ifdef __MSDOS__
+
+#include "hal.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <conio.h>
+#include <dos.h>
+#include <i86.h>     /* OpenWatcom int86() */
+
+static int cursor_row = 0;
+static int cursor_col = 0;
+static int screen_cols = 80;
+static int screen_rows = 25;
+
+/* --- BIOS video services (INT 10h) --- */
+
+static void bios_set_cursor(int row, int col)
+{
+    union REGS r;
+    r.h.ah = 0x02;      /* Set cursor position */
+    r.h.bh = 0;         /* Page 0 */
+    r.h.dh = (uint8_t)row;
+    r.h.dl = (uint8_t)col;
+    int86(0x10, &r, &r);
+    cursor_row = row;
+    cursor_col = col;
+}
+
+static void bios_get_cursor(int *row, int *col)
+{
+    union REGS r;
+    r.h.ah = 0x03;      /* Get cursor position */
+    r.h.bh = 0;
+    int86(0x10, &r, &r);
+    *row = r.h.dh;
+    *col = r.h.dl;
+}
+
+static void bios_scroll_up(int lines, int attr, int r1, int c1, int r2, int c2)
+{
+    union REGS r;
+    r.h.ah = 0x06;      /* Scroll window up */
+    r.h.al = (uint8_t)lines;
+    r.h.bh = (uint8_t)attr;
+    r.h.ch = (uint8_t)r1;
+    r.h.cl = (uint8_t)c1;
+    r.h.dh = (uint8_t)r2;
+    r.h.dl = (uint8_t)c2;
+    int86(0x10, &r, &r);
+}
+
+static void bios_write_char(int ch, int attr)
+{
+    union REGS r;
+    r.h.ah = 0x09;      /* Write char + attribute */
+    r.h.al = (uint8_t)ch;
+    r.h.bh = 0;
+    r.h.bl = (uint8_t)attr;
+    r.x.cx = 1;
+    int86(0x10, &r, &r);
+}
+
+/* --- Terminal I/O --- */
+
+static void dos_putch(int ch)
+{
+    if (ch == '\n') {
+        cursor_col = 0;
+        cursor_row++;
+        if (cursor_row >= screen_rows) {
+            bios_scroll_up(1, 0x07, 0, 0, screen_rows - 1, screen_cols - 1);
+            cursor_row = screen_rows - 1;
+        }
+        bios_set_cursor(cursor_row, cursor_col);
+    } else if (ch == '\r') {
+        cursor_col = 0;
+        bios_set_cursor(cursor_row, cursor_col);
+    } else if (ch == '\b') {
+        if (cursor_col > 0) cursor_col--;
+        bios_set_cursor(cursor_row, cursor_col);
+    } else {
+        bios_write_char(ch, 0x07);
+        cursor_col++;
+        if (cursor_col >= screen_cols) {
+            cursor_col = 0;
+            cursor_row++;
+            if (cursor_row >= screen_rows) {
+                bios_scroll_up(1, 0x07, 0, 0, screen_rows - 1, screen_cols - 1);
+                cursor_row = screen_rows - 1;
+            }
+        }
+        bios_set_cursor(cursor_row, cursor_col);
+    }
+}
+
+static void dos_puts(const char *s)
+{
+    while (*s)
+        dos_putch(*s++);
+}
+
+static int dos_getch(void)
+{
+    /* INT 16h AH=00: wait for key, return AL=ASCII, AH=scan */
+    union REGS r;
+    r.h.ah = 0x00;
+    int86(0x16, &r, &r);
+    return r.h.al ? r.h.al : (0x100 | r.h.ah); /* extended key */
+}
+
+static bool dos_kbhit(void)
+{
+    return kbhit() != 0;
+}
+
+static void dos_locate(int row, int col)
+{
+    bios_set_cursor(row, col);
+}
+
+static int dos_get_cursor_row(void) { return cursor_row; }
+static int dos_get_cursor_col(void) { return cursor_col; }
+
+static void dos_cls(void)
+{
+    bios_scroll_up(0, 0x07, 0, 0, screen_rows - 1, screen_cols - 1);
+    bios_set_cursor(0, 0);
+}
+
+static void dos_set_width(int cols)
+{
+    (void)cols;
+}
+
+/* DOS doesn't have raw/cooked mode distinction for console */
+static void dos_enable_raw(void)  { }
+static void dos_disable_raw(void) { }
+
+static void dos_write_raw(const char *data, int len)
+{
+    /* On DOS, write directly to screen buffer for graphics.
+     * For text, just output character by character. */
+    for (int i = 0; i < len; i++)
+        dos_putch(data[i]);
+}
+
+/* --- Lifecycle --- */
+
+static void dos_init(void)
+{
+    /* Get current video mode to determine screen size */
+    union REGS r;
+    r.h.ah = 0x0F;  /* Get video mode */
+    int86(0x10, &r, &r);
+    screen_cols = r.h.ah;
+
+    /* Get screen rows from BIOS data area */
+    /* 0040:0084 = rows - 1 */
+    screen_rows = *(uint8_t far *)MK_FP(0x0040, 0x0084) + 1;
+    if (screen_rows < 25) screen_rows = 25;
+
+    bios_get_cursor(&cursor_row, &cursor_col);
+}
+
+static void dos_shutdown(void)
+{
+    /* Nothing to clean up on DOS */
+}
+
+/* --- HAL vtable --- */
+
+static hal_ops_t dos_hal = {
+    .putch       = dos_putch,
+    .puts        = dos_puts,
+    .getch       = dos_getch,
+    .kbhit       = dos_kbhit,
+    .locate      = dos_locate,
+    .get_cursor_row = dos_get_cursor_row,
+    .get_cursor_col = dos_get_cursor_col,
+    .cls         = dos_cls,
+    .set_width   = dos_set_width,
+    .enable_raw  = dos_enable_raw,
+    .disable_raw = dos_disable_raw,
+    .write_raw   = dos_write_raw,
+    .screen_width  = 80,
+    .screen_height = 25,
+    .is_tty      = true,  /* DOS console is always a TTY */
+    .init        = dos_init,
+    .shutdown    = dos_shutdown,
+};
+
+hal_ops_t *hal_dos_create(void)
+{
+    return &dos_hal;
+}
+
+#endif /* __MSDOS__ */
@@ -79,7 +79,11 @@ int gwrt_resume_label;

 void gwrt_init(void)
 {
+#ifdef __MSDOS__
+    gw_hal = hal_dos_create();
+#else
    gw_hal = hal_posix_create();
+#endif
    gw_hal->init();
    memset(&gw, 0, sizeof(gw));
    for (int i = 0; i < 26; i++)
@@ -167,7 +167,11 @@ static void print_banner(int interactive)

 int main(int argc, char **argv)
 {
+#ifdef __MSDOS__
+    gw_hal = hal_dos_create();
+#else
    gw_hal = hal_posix_create();
+#endif
    gw_hal->init();
    gw_init();
    strpool_init(STRPOOL_DEFAULT_SIZE);