fix(sdk): geos-cbm support

Author: kassane

build.zig

@@ -23,6 +23,7 @@ const SdkLibs = struct {
     a2600_3e: ?sdk_mod.Libs = null,
     a8cart: ?sdk_mod.Libs = null,
     snes: ?sdk_mod.Libs = null,
+    geos_cbm: ?sdk_mod.Libs = null,
 };
 
 pub fn build(b: *std.Build) void {
@@ -64,6 +65,7 @@ pub fn build(b: *std.Build) void {
         .{ .name = "atari2600-3e", .query = .{ .cpu_arch = .mos, .os_tag = .atari2600 } },
         .{ .name = "atari8-cart-std", .query = .{ .cpu_arch = .mos, .os_tag = .atari8 } },
         .{ .name = "snes", .query = .{ .cpu_arch = .mos, .os_tag = .snes } },
+        .{ .name = "geos-cbm", .query = .{ .cpu_arch = .mos, .os_tag = .geos_cbm } },
     }) |pd| {
         const libs = sdk_mod.buildPlatform(b, sdk_src_raw, pd, optimize);
         const dest = b.fmt("mos-platform/{s}/lib", .{pd.name});
@@ -93,6 +95,7 @@ pub fn build(b: *std.Build) void {
         if (std.mem.eql(u8, pd.name, "atari2600-3e")) sdk_libs.a2600_3e = libs;
         if (std.mem.eql(u8, pd.name, "atari8-cart-std")) sdk_libs.a8cart = libs;
         if (std.mem.eql(u8, pd.name, "snes")) sdk_libs.snes = libs;
+        if (std.mem.eql(u8, pd.name, "geos-cbm")) sdk_libs.geos_cbm = libs;
     }
 
     // Translate neslib.h and nesdoug.h from the MOS SDK into Zig modules.
@@ -434,6 +437,16 @@ pub fn build(b: *std.Build) void {
         run_bininfo.addFileArg(exe.getEmittedBin());
     }
 
+    // ---- GEOS CBM hello ----
+    {
+        const step = b.step("geos-hello", "Build GEOS CBM hello example");
+        const exe = addGeosExe(b, sdk_src, sdk_dep, sdk_libs.geos_cbm orelse @panic("geos-cbm libs not built"), optimize, "geos-hello", "geos/hello/hello.zig");
+        const install = b.addInstallArtifact(exe, .{ .dest_sub_path = "geos-hello.cvt" });
+        step.dependOn(&install.step);
+        b.getInstallStep().dependOn(&install.step);
+        run_bininfo.addFileArg(exe.getEmittedBin());
+    }
+
     // ---- MEGA65 (mega65-libc fetched automatically via build.zig.zon) ----
     if (b.lazyDependency("mega65-libc", .{})) |m65_dep| {
         {
@@ -2039,6 +2052,84 @@ fn simIoHeaderMod(
     return tc.createModule();
 }
 
+fn geosHeaderMod(
+    b: *std.Build,
+    sdk_dep: *std.Build.Dependency,
+    target: std.Build.ResolvedTarget,
+    opt: std.builtin.OptimizeMode,
+) *std.Build.Module {
+    const tc = b.addTranslateC(.{
+        // geos_zig.h suppresses _Static_assert (struct-size checks fail during translation)
+        .root_source_file = b.path("geos/geos_zig.h"),
+        .target = target,
+        .optimize = opt,
+        .link_libc = false,
+    });
+    tc.addIncludePath(sdk_dep.path("mos-platform/geos-cbm"));
+    tc.addIncludePath(sdk_dep.path("mos-platform/common/include"));
+    return tc.createModule();
+}
+
+fn addGeosExe(
+    b: *std.Build,
+    sdk_src: []const u8,
+    sdk_dep: *std.Build.Dependency,
+    libs: sdk_mod.Libs,
+    opt: std.builtin.OptimizeMode,
+    name: []const u8,
+    root_src: []const u8,
+) *std.Build.Step.Compile {
+    const target = b.resolveTargetQuery(.{ .cpu_arch = .mos, .os_tag = .geos_cbm });
+
+    const wf = b.addWriteFiles();
+    const libc_txt = wf.add("libc.txt", b.fmt(
+        "include_dir={s}/mos-platform/geos-cbm\n" ++
+            "sys_include_dir={s}/mos-platform/common/include\n" ++
+            "crt_dir={s}/mos-platform/geos-cbm\n" ++
+            "msvc_lib_dir=\nkernel32_lib_dir=\ngcc_dir=\n",
+        .{ sdk_src, sdk_src, sdk_src },
+    ));
+    // vlir.ld is the GEOS VLIR linker script (produces .cvt binary via OUTPUT_FORMAT FULL blocks).
+    // It includes c.ld (common sections) and geos.ld (GEOS symbol table) via INCLUDE directives,
+    // both resolved through the SEARCH_DIRs below.
+    const wrapper_ld = wf.add("geos-cbm-wrapper.ld", b.fmt(
+        \\SEARCH_DIR("{s}/mos-platform/geos-cbm");
+        \\SEARCH_DIR("{s}/mos-platform/common/ldscripts");
+        \\INCLUDE "vlir.ld"
+    , .{ sdk_src, sdk_src }));
+
+    const exe = b.addExecutable(.{
+        .name = name,
+        .root_module = b.createModule(.{
+            .root_source_file = b.path(root_src),
+            .target = target,
+            .optimize = opt,
+            .sanitize_c = .off,
+        }),
+    });
+    exe.bundle_compiler_rt = false;
+    exe.lto = .full;
+    exe.forceUndefinedSymbol("__zig_call_main_section");
+    exe.forceUndefinedSymbol("main");
+    if (libs.crt0_obj) |obj| exe.root_module.addObject(obj);
+    exe.root_module.linkLibrary(libs.crt);
+    exe.root_module.linkLibrary(libs.crt0);
+    exe.root_module.linkLibrary(libs.c);
+    if (libs.mem) |mem_obj| exe.root_module.addObject(mem_obj);
+    exe.setLibCFile(libc_txt);
+    exe.root_module.link_libc = true;
+    exe.setLinkerScript(wrapper_ld);
+    exe.root_module.addImport("mos_panic", b.createModule(.{
+        .root_source_file = b.path("sdk/panic.zig"),
+        .target = target,
+        .optimize = opt,
+        .sanitize_c = .off,
+    }));
+    exe.root_module.addImport("geos", geosHeaderMod(b, sdk_dep, target, opt));
+
+    return exe;
+}
+
 fn addApple2Exe(
     b: *std.Build,
     sdk_src: []const u8,

geos/geos_zig.h

@@ -0,0 +1,5 @@
+// Wrapper header for translate-c.
+// _Static_assert with struct-size checks fails during translation because
+// the host-side sizeof differs from the target layout. Suppress it here.
+#define _Static_assert(cond, msg)
+#include "geos.h"

geos/hello/hello.zig

@@ -0,0 +1,55 @@
+// Copyright (c) 2024 Matheus C. França
+// SPDX-License-Identifier: Apache-2.0
+pub const panic = @import("mos_panic");
+
+const geos = @import("geos");
+
+// Clear screen: pattern 2 (white), rectangle from (0,0) to (319,199)
+// WORD(x) expands to lo,hi bytes: WORD(0)=0,0  WORD(319)=0x3F,0x01
+const clear_screen = [_]u8{
+    geos.NEWPATTERN,  2,
+    geos.MOVEPENTO,   0,
+    0,                0,
+    geos.RECTANGLETO, 0x3F,
+    0x01,             199,
+    0,
+};
+
+const hello_str = "Hello, Zig!" ++ [_]u8{0};
+
+// GEOS zero-page argument registers (geos.ld)
+fn r0() *volatile u16 {
+    return @ptrFromInt(0x0002);
+} // __r0 = str ptr / GraphicsString arg
+fn r1H() *volatile u8 {
+    return @ptrFromInt(0x0005);
+} // __r1H = y
+fn r11() *volatile u16 {
+    return @ptrFromInt(0x0018);
+} // __r11 = x
+
+// Raw GEOS kernel jump table entries (geos.ld)
+extern fn __GraphicsString() void; // 0xc136
+extern fn __PutString() void; // 0xc148
+extern fn __UseSystemFont() void; // 0xc14b
+extern fn __MainLoop() void; // 0xc1c3
+
+fn graphicsString(graph_string: [*]const u8) void {
+    r0().* = @intFromPtr(graph_string);
+    __GraphicsString();
+}
+
+fn putString(x: u16, y: u8, str: [*:0]const u8) void {
+    r11().* = x;
+    r1H().* = y;
+    r0().* = @intFromPtr(str);
+    __PutString();
+}
+
+export fn main() void {
+    geos.dispBufferOn = geos.ST_WR_FORE | geos.ST_WR_BACK;
+    graphicsString(&clear_screen);
+    __UseSystemFont();
+    putString(80, 90, hello_str[0.. :0].ptr);
+    __MainLoop();
+}

sdk/build.zig

@@ -977,11 +977,11 @@ fn buildGeosCbm(
     libcrt0.root_module.addIncludePath(.{ .cwd_relative = com_inc });
     libcrt0.root_module.addCSourceFiles(.{
         .root = .{ .cwd_relative = plat_dir },
-        .files = &.{ "crt0.c", "geos_crt.c" },
+        .files = &.{"crt0.c"},
     });
     libcrt0.root_module.addCSourceFiles(.{
         .root = .{ .cwd_relative = crt0_dir },
-        .files = &.{ "crt0.S", "init-stack.S", "copy-zp-data.c", "zero-bss.c" },
+        .files = &.{ "init-stack.S", "copy-zp-data.c", "zero-bss.c" },
     });
 
     const libc = addLib(b, "c", target, opt);
@@ -991,7 +991,26 @@ fn buildGeosCbm(
         .files = &.{"mem.c"},
     });
 
-    return .{ .crt = libcrt, .crt0 = libcrt0, .c = libc };
+    const mem_obj = b.addObject(.{
+        .name = "mem",
+        .root_module = b.createModule(.{ .target = target, .optimize = opt }),
+    });
+    mem_obj.root_module.addCSourceFiles(.{ .root = b.path("sdk"), .files = &.{"mem.s"} });
+    mem_obj.lto = .none;
+
+    const crt0_obj = b.addObject(.{
+        .name = "crt0",
+        .root_module = b.createModule(.{ .target = target, .optimize = opt }),
+    });
+    crt0_obj.root_module.addIncludePath(.{ .cwd_relative = com_asm });
+    crt0_obj.root_module.addIncludePath(.{ .cwd_relative = com_inc });
+    crt0_obj.root_module.addCSourceFiles(.{
+        .root = .{ .cwd_relative = crt0_dir },
+        .files = &.{"crt0.S"},
+    });
+    crt0_obj.lto = .none;
+
+    return .{ .crt = libcrt, .crt0 = libcrt0, .c = libc, .mem = mem_obj, .crt0_obj = crt0_obj };
 }
 
 fn buildC128(