progress towards baremetal

build.zig

@@ -1,11 +1,17 @@
 const std = @import("std");
 const builtin = @import("builtin");
 
-fn addEngineSources(b: *std.Build, c: *std.Build.Step.Compile, target: std.Build.ResolvedTarget, optimize: std.builtin.OptimizeMode) void {
+const LibBuildOpts = struct {
+    target: std.Build.ResolvedTarget,
+    optimize: std.builtin.OptimizeMode,
+    baremetal: bool,
+};
+
+fn addEngineSources(b: *std.Build, c: *std.Build.Step.Compile, opts: LibBuildOpts) void {
     const dataMod = b.createModule(.{
         .root_source_file = b.path("src/data.zig"),
-        .target = target,
+        .target = opts.target,
-        .optimize = optimize,
+        .optimize = opts.optimize,
     });
     const zigObj = b.addObject(.{
         .name = "zig_wrappers",
@@ -13,12 +19,9 @@ fn addEngineSources(b: *std.Build, c: *std.Build.Step.Compile, target: std.Build
         .pic = true,
     });
     c.addObject(zigObj);
-    
+   
-    c.linkLibC(); // we need a libc
-
     c.addCSourceFiles(.{
         .files = &[_][]const u8{
-            "src/tinycthread.c",
             "src/lock.c",
             "src/utils.c",
             "src/value.c",
@@ -34,8 +37,20 @@ fn addEngineSources(b: *std.Build, c: *std.Build.Step.Compile, target: std.Build
             "src/components/gpu.c",
             "src/components/keyboard.c",
         },
+        .flags = &.{
+            if(opts.baremetal) "-DNN_BAREMETAL" else "",
+        },
     });
 
+    if(!opts.baremetal) {
+        c.linkLibC(); // we need a libc
+        c.addCSourceFiles(.{
+            .files = &.{
+                "src/tinycthread.c",
+            },
+        });
+    }
+
     c.addIncludePath(b.path("src"));
 }
 
@@ -92,6 +107,12 @@ pub fn build(b: *std.Build) void {
 
     const optimize = b.standardOptimizeOption(.{});
 
+    const opts = LibBuildOpts {
+        .target = target,
+        .optimize = optimize,
+        .baremetal = b.option(bool, "baremetal", "Compiles without libc integration") orelse false,
+    };
+
     const includeFiles = b.addInstallHeaderFile(b.path("src/neonucleus.h"), "neonucleus.h");
 
     const engineStatic = b.addStaticLibrary(.{
@@ -101,7 +122,7 @@ pub fn build(b: *std.Build) void {
         .optimize = optimize,
     });
 
-    addEngineSources(b, engineStatic, target, optimize);
+    addEngineSources(b, engineStatic, opts);
 
     const engineShared = b.addSharedLibrary(.{
         .name = getSharedEngineName(os),
@@ -109,7 +130,7 @@ pub fn build(b: *std.Build) void {
         .optimize = optimize,
     });
 
-    addEngineSources(b, engineShared, target, optimize);
+    addEngineSources(b, engineShared, opts);
 
     const engineStep = b.step("engine", "Builds the engine as a static library");
     engineStep.dependOn(&engineStatic.step);
@@ -162,24 +183,4 @@ pub fn build(b: *std.Build) void {
     const run_step = b.step("run", "Run the emulator");
     run_step.dependOn(emulatorStep);
     run_step.dependOn(&run_cmd.step);
-
-    const lib_unit_tests = b.addTest(.{
-        .root_source_file = b.path("src/engine.zig"),
-        .target = target,
-        .optimize = optimize,
-    });
-
-    const run_lib_unit_tests = b.addRunArtifact(lib_unit_tests);
-
-    const exe_unit_tests = b.addTest(.{
-        .root_source_file = b.path("src/main.zig"),
-        .target = target,
-        .optimize = optimize,
-    });
-
-    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
-
-    const test_step = b.step("test", "Run unit tests");
-    test_step.dependOn(&run_lib_unit_tests.step);
-    test_step.dependOn(&run_exe_unit_tests.step);
 }

src/components/drive.c

@@ -1,5 +1,4 @@
 #include "../neonucleus.h"
-#include <stdio.h>
 #include <string.h>
 
 void nn_drive_destroy(void *_, nn_component *component, nn_drive *drive) {

src/components/filesystem.c

@@ -1,5 +1,4 @@
 #include "../neonucleus.h"
-#include <stdio.h>
 #include <string.h>
 
 void nn_fs_destroy(void *_, nn_component *component, nn_filesystem *fs) {

src/components/gpu.c

@@ -1,7 +1,5 @@
 #include "../neonucleus.h"
 #include "screen.h"
-#include <stdio.h>
-#include <string.h>
 
 typedef struct nni_gpu {
     nn_Alloc alloc;
@@ -173,7 +171,7 @@ void nni_gpu_get(nni_gpu *gpu, void *_, nn_component *component, nn_computer *co
 
 void nni_gpu_getScreen(nni_gpu *gpu, void *_, nn_component *component, nn_computer *computer) {
     if(gpu->screenAddress == NULL) return;
-    nn_return_string(computer, gpu->screenAddress, strlen(gpu->screenAddress));
+    nn_return_string(computer, gpu->screenAddress, nn_strlen(gpu->screenAddress));
 }
 
 void nni_gpu_maxResolution(nni_gpu *gpu, void *_, nn_component *component, nn_computer *computer) {

src/components/screen.c

@@ -1,6 +1,4 @@
 #include "screen.h"
-#include <stdio.h>
-#include <string.h>
 
 nn_screen *nn_newScreen(nn_Context *context, int maxWidth, int maxHeight, int maxDepth, int editableColors, int paletteColors) {
     nn_Alloc *alloc = &context->allocator;
@@ -20,7 +18,7 @@ nn_screen *nn_newScreen(nn_Context *context, int maxWidth, int maxHeight, int ma
     screen->editableColors = editableColors;
     screen->paletteColors = paletteColors;
     screen->palette = nn_alloc(alloc, sizeof(int) * screen->paletteColors);
-    memset(screen->palette, 0, sizeof(int) * screen->paletteColors);
+    nn_memset(screen->palette, 0, sizeof(int) * screen->paletteColors);
     screen->aspectRatioWidth = 1;
     screen->aspectRatioHeight = 1;
     screen->isOn = true;
@@ -97,7 +95,7 @@ void nn_addKeyboard(nn_screen *screen, nn_address address) {
 void nn_removeKeyboard(nn_screen *screen, nn_address address) {
     size_t j = 0;
     for(size_t i = 0; i < screen->keyboardCount; i++) {
-        if(strcmp(screen->keyboards[i], address) == 0) {
+        if(nn_strcmp(screen->keyboards[i], address) == 0) {
             nn_deallocStr(&screen->ctx.allocator, screen->keyboards[i]);
         } else {
             screen->keyboards[j] = screen->keyboards[i];
@@ -217,7 +215,7 @@ void nn_screenComp_getKeyboards(nn_screen *screen, void *_, nn_component *compon
 
     size_t len = arr.array->len;
     for(size_t i = 0; i < len; i++) {
-        size_t addrlen = strlen(nn_getKeyboard(screen, i));
+        size_t addrlen = nn_strlen(nn_getKeyboard(screen, i));
         nn_value addr = nn_values_string(&screen->ctx.allocator, nn_getKeyboard(screen, i), addrlen);
         nn_values_set(arr, i, addr);
     }

src/lock.c

@@ -1,5 +1,4 @@
 #include "neonucleus.h"
-#include <stdio.h>
 
 #ifndef NN_BAREMETAL
 #include "tinycthread.h"

src/neonucleus.h

@@ -149,7 +149,11 @@ typedef struct nn_Context {
     nn_Rng rng;
 } nn_Context;
 
-// TODO: write a bunch of utils so this *can* work on baremetal.
+// libc-like utils
+
+void nn_memset(void *buf, unsigned char byte, size_t len);
+int nn_strcmp(const char *a, const char *b);
+size_t nn_strlen(const char *a);
 
 #ifndef NN_BAREMETAL
 nn_Alloc nn_libcAllocator();

src/unicode.c

@@ -1,6 +1,4 @@
 #include "neonucleus.h"
-#include <assert.h>
-#include <stdio.h>
 #include <string.h>
 
 // both tables copied from: https://github.com/MightyPirates/OpenComputers/blob/52da41b5e171b43fea80342dc75d808f97a0f797/src/main/scala/li/cil/oc/util/FontUtils.scala
@@ -225,9 +223,6 @@ char *nn_unicode_char(nn_Alloc *alloc, unsigned int *codepoints, size_t codepoin
         j += codepointLen;
     }
     buf[j] = '\0';
-    // this can only fail if size_t is smaller than a pointer and overflowed.
-    // IF THIS HAPPENS, THE SYSTEM HEADERS ARE BUGGED.
-    assert(j == len);
 
     return buf;
 }

src/utils.c

@@ -204,3 +204,32 @@ int nn_mapColor(int color, int *palette, int paletteSize) {
     }
     return bestColor;
 }
+
+void nn_memset(void *buf, unsigned char byte, size_t len) {
+    unsigned char *bytes = buf;
+    for(size_t i = 0; i < len; i++) bytes[i] = byte;
+}
+
+int nn_strcmp(const char *a, const char *b) {
+    size_t i = 0;
+    while(true) {
+        unsigned char ca = a[i];
+        unsigned char cb = b[i];
+
+        if(ca < cb) {
+            return -1;
+        }
+        if(ca > cb) {
+            return -1;
+        }
+        if(ca == 0 && cb == 0) { // reached terminator
+            return 0;
+        }
+    }
+}
+
+size_t nn_strlen(const char *a) {
+    size_t l = 0;
+    while(a[l]) l++;
+    return l;
+}