Migrate the C codebase to C++20

.gitignore

@@ -46,3 +46,7 @@ workspace/.container_runtime
 AGENTS.md
 CLAUDE.md
 .worktrees/
+
+# local tooling data (headroom memory, graphify output)
+.headroom/
+graphify-out/

workspace/all/batmon/batmon.c → workspace/all/batmon/batmon.cpp

@@ -1,17 +1,21 @@
 // heavily modified from the Onion original: https://github.com/OnionUI/Onion/tree/main/src/batmon
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdbool.h>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <unistd.h>
 #include <pthread.h>
 #include <signal.h>
 
+#include <sqlite3.h>
+
+// Project + libbatmondb C headers declare C-linkage symbols defined in the
+// still-C common/ and libbatmondb translation units; include them as extern "C"
+// so this C++ unit links against the unmangled names.
+extern "C" {
 #include <defines.h>
 #include <api.h>
-
-#include <sqlite3.h>
 #include <batmondb.h>
+}
 
 #define CHECK_BATTERY_TIMEOUT_S 15 // s - check battery percentage every 15s
 
@@ -24,7 +28,7 @@ static bool is_suspended = false;
 
 int battery_current_state_duration = 0;
 int best_session_time = 0;
-char *device_model = NULL;
+char *device_model = nullptr;
 
 void register_handler();
 void sigintHandler(int signum) {

workspace/all/batmon/makefile

@@ -21,18 +21,29 @@ SDL?=SDL
 
 TARGET = batmon
 INCDIR = -I. -I../common/ -I../../$(PLATFORM)/platform/
-SOURCE = $(TARGET).c ../common/utils.c ../common/api.c ../common/config.c ../common/scaler.c ../../$(PLATFORM)/platform/platform.c
+# Shared common/ + platform stay C; the tool itself is C++20. Compile the C
+# units to objects, then compile the .cpp and link everything through g++.
+SOURCE = -c ../../$(PLATFORM)/platform/platform.cpp
+CXXSOURCE = $(TARGET).cpp ../common/utils.cpp ../common/config.cpp ../common/scaler.cpp ../common/api.cpp
+CXXSOURCE += build/$(PLATFORM)/platform.o
 
 CC = $(CROSS_COMPILE)gcc
+CXX = $(CROSS_COMPILE)g++
+# Prefer real C++20; fall back to gnu++2a on older toolchains (e.g. the current
+# gcc 8.3 tg5040 cross-compiler, which predates the -std=gnu++20 spelling).
+CXXSTD := $(shell printf 'int main(){return 0;}' | $(CXX) -std=gnu++20 -x c++ - -o /dev/null >/dev/null 2>&1 && echo gnu++20 || echo gnu++2a)
 CFLAGS  += $(OPT)
-CFLAGS  += $(INCDIR) -DPLATFORM=\"$(PLATFORM)\" -std=gnu99
+CFLAGS  += $(INCDIR) -DPLATFORM=\"$(PLATFORM)\"
+CXXFLAGS += $(CFLAGS) -std=$(CXXSTD)
 LDFLAGS	 += -lmsettings -lbatmondb -lsqlite3
 
 PRODUCT= build/$(PLATFORM)/$(TARGET).elf
 
 all: $(PREFIX_LOCAL)/include/msettings.h $(PREFIX_LOCAL)/include/batmondb.h
 	mkdir -p build/$(PLATFORM)
-	$(CC) $(SOURCE) -o $(PRODUCT) $(CFLAGS) $(LDFLAGS)
+	$(CXX) $(SOURCE) $(CXXFLAGS) $(LDFLAGS)
+	mv platform.o build/$(PLATFORM)
+	$(CXX) $(CXXSOURCE) -o $(PRODUCT) $(CXXFLAGS) $(LDFLAGS) -lstdc++
 clean:
 	rm -f $(PRODUCT)
 

workspace/all/battery/battery.c → workspace/all/battery/battery.cpp

@@ -1,16 +1,20 @@
 // heavily modified from the Onion original: https://github.com/OnionUI/Onion/tree/main/src/batteryMonitorUI
-#include <stdio.h>
+#include <cstdio>
 #include <unistd.h>
-#include <stdbool.h>
-#include <signal.h>
-#include <msettings.h>
+#include <csignal>
+#include <cstdlib>
+
+#include <sqlite3.h>
 
+// Project + libbatmondb C headers declare C-linkage symbols defined in the
+// still-C common/ and libbatmondb translation units; include as extern "C".
+extern "C" {
+#include <msettings.h>
 #include "defines.h"
 #include "api.h"
 #include "utils.h"
-
-#include <sqlite3.h>
 #include <batmondb.h>
+}
 
 #define GRAPH_LINE_WIDTH 1
 
@@ -126,8 +130,8 @@ static void sigHandler(int sig)
 
 static SDL_Surface *screen;
 
-char *device_model = NULL;
-sqlite3 *bat_log_db = NULL;
+char *device_model = nullptr;
+sqlite3 *bat_log_db = nullptr;
 
 void secondsToHoursMinutes(int seconds, char *output)
 {
@@ -196,8 +200,10 @@ int _renderText(const char *text, TTF_Font *font, SDL_Color color, SDL_Rect *rec
     if (textSurface != NULL)
     {
         text_width = textSurface->w;
-        if (right_align)
-            SDL_BlitSurface(textSurface, NULL, screen, &(SDL_Rect){rect->x - textSurface->w, rect->y, rect->w, rect->h});
+        if (right_align) {
+            SDL_Rect r = {rect->x - textSurface->w, rect->y, rect->w, rect->h};
+            SDL_BlitSurface(textSurface, NULL, screen, &r);
+        }
         else
             SDL_BlitSurface(textSurface, NULL, screen, rect);
         SDL_FreeSurface(textSurface);
@@ -395,18 +401,20 @@ void drawBatteryIcon(int percent, SDL_Rect dst) {
     int x = dst.x;
     int y = dst.y;
     //SDL_Rect rect = asset_rects[ASSET_BATTERY];
-    SDL_Rect rect = (SDL_Rect){SCALE4(47,51,17,10)};
-    GFX_blitAsset(ASSET_BATTERY, NULL, screen, &(SDL_Rect){x,y});
+    SDL_Rect rect = {SCALE4(47,51,17,10)};
+    SDL_Rect battery_dst = {x,y};
+    GFX_blitAsset(ASSET_BATTERY, NULL, screen, &battery_dst);
     //rect = asset_rects[ASSET_BATTERY_FILL];
-    rect = (SDL_Rect){SCALE4(81,33,12,6)};
+    rect = SDL_Rect{SCALE4(81,33,12,6)};
     SDL_Rect clip = rect;
     clip.w *= percent;
     clip.w /= 100;
     if (clip.w<=0) return;
     clip.x = rect.w - clip.w;
     clip.y = 0;
-
-    GFX_blitAsset(ASSET_BATTERY_FILL, &clip, screen, &(SDL_Rect){x+SCALE1(3)+clip.x,y+SCALE1(2)});
+
+    SDL_Rect fill_dst = {x+SCALE1(3)+clip.x,y+SCALE1(2)};
+    GFX_blitAsset(ASSET_BATTERY_FILL, &clip, screen, &fill_dst);
 }
 
 void renderPage()
@@ -453,29 +461,37 @@ void renderPage()
     switch_zoom_profile(segment_duration);
 
     // x axis labels
-    renderText(label[0], font.small, COLOR_WHITE, &(SDL_Rect){graph.layout.label1_x, graph.layout.label_y, 32, 32});
-    renderText(label[1], font.small, COLOR_WHITE, &(SDL_Rect){graph.layout.label2_x, graph.layout.label_y, 32, 32});
-    renderText(label[2], font.small, COLOR_WHITE, &(SDL_Rect){graph.layout.label3_x, graph.layout.label_y, 32, 32});
-    renderText(label[3], font.small, COLOR_WHITE, &(SDL_Rect){graph.layout.label4_x, graph.layout.label_y, 32, 32});
+    SDL_Rect lbl0 = {graph.layout.label1_x, graph.layout.label_y, 32, 32};
+    renderText(label[0], GFX_getFonts()->small, COLOR_WHITE, &lbl0);
+    SDL_Rect lbl1 = {graph.layout.label2_x, graph.layout.label_y, 32, 32};
+    renderText(label[1], GFX_getFonts()->small, COLOR_WHITE, &lbl1);
+    SDL_Rect lbl2 = {graph.layout.label3_x, graph.layout.label_y, 32, 32};
+    renderText(label[2], GFX_getFonts()->small, COLOR_WHITE, &lbl2);
+    SDL_Rect lbl3 = {graph.layout.label4_x, graph.layout.label_y, 32, 32};
+    renderText(label[3], GFX_getFonts()->small, COLOR_WHITE, &lbl3);
 
     // y axis "labels"
-    drawBatteryIcon(100, (SDL_Rect){graph.layout.icon_x, graph.layout.icon1_y});
-    drawBatteryIcon(66, (SDL_Rect){graph.layout.icon_x, graph.layout.icon2_y});
-    drawBatteryIcon(33, (SDL_Rect){graph.layout.icon_x, graph.layout.icon3_y});
-    drawBatteryIcon(0, (SDL_Rect){graph.layout.icon_x, graph.layout.icon4_y});
+    drawBatteryIcon(100, SDL_Rect{graph.layout.icon_x, graph.layout.icon1_y});
+    drawBatteryIcon(66, SDL_Rect{graph.layout.icon_x, graph.layout.icon2_y});
+    drawBatteryIcon(33, SDL_Rect{graph.layout.icon_x, graph.layout.icon3_y});
+    drawBatteryIcon(0, SDL_Rect{graph.layout.icon_x, graph.layout.icon4_y});
 
     char text_line[255];
     sprintf(text_line, "Since Charge: %s", session_duration);
-    renderText(text_line, font.medium, COLOR_WHITE, &(SDL_Rect){graph.layout.label_session_x, graph.layout.label_session_y, graph.layout.label_size_x, graph.layout.label_size_y});
+    SDL_Rect session_rect = {graph.layout.label_session_x, graph.layout.label_session_y, graph.layout.label_size_x, graph.layout.label_size_y};
+    renderText(text_line, GFX_getFonts()->medium, COLOR_WHITE, &session_rect);
 
     sprintf(text_line, "Current: %s", current_percentage);
-    renderText(text_line, font.medium, COLOR_WHITE, &(SDL_Rect){graph.layout.label_current_x, graph.layout.label_current_y, graph.layout.label_size_x, graph.layout.label_size_y});
+    SDL_Rect current_rect = {graph.layout.label_current_x, graph.layout.label_current_y, graph.layout.label_size_x, graph.layout.label_size_y};
+    renderText(text_line, GFX_getFonts()->medium, COLOR_WHITE, &current_rect);
 
     sprintf(text_line, "Remaining: %s", session_left);
-    renderTextAlignRight(text_line, font.medium, COLOR_WHITE, &(SDL_Rect){graph.layout.label_left_x, graph.layout.label_left_y, graph.layout.label_size_x, graph.layout.label_size_y});
+    SDL_Rect left_rect = {graph.layout.label_left_x, graph.layout.label_left_y, graph.layout.label_size_x, graph.layout.label_size_y};
+    renderTextAlignRight(text_line, GFX_getFonts()->medium, COLOR_WHITE, &left_rect);
 
     sprintf(text_line, "Longest: %s", session_best);
-    renderTextAlignRight(text_line, font.medium, COLOR_WHITE, &(SDL_Rect){graph.layout.label_best_x, graph.layout.label_best_y, graph.layout.label_size_x, graph.layout.label_size_y});
+    SDL_Rect best_rect = {graph.layout.label_best_x, graph.layout.label_best_y, graph.layout.label_size_x, graph.layout.label_size_y};
+    renderTextAlignRight(text_line, GFX_getFonts()->medium, COLOR_WHITE, &best_rect);
 
     int half_line_width = (int)(GRAPH_LINE_WIDTH) / 2;
 
@@ -556,8 +572,10 @@ void renderPage()
             }
         }
         SDL_UnlockSurface(screen);
-        if (x_end != 0)
-            GFX_blitAsset(ASSET_BATTERY_LOW, NULL, screen, &(SDL_Rect){x_end, y_end});
+        if (x_end != 0) {
+            SDL_Rect low_dst = {x_end, y_end};
+            GFX_blitAsset(ASSET_BATTERY_LOW, NULL, screen, &low_dst);
+        }
     }
 }
 
@@ -746,25 +764,33 @@ int main(int argc, char *argv[])
                 }
 
                 char title[256];
-                int text_width = GFX_truncateText(font.large, display_name, title, max_width, SCALE1(BUTTON_PADDING * 2));
+                int text_width = GFX_truncateText(GFX_getFonts()->large, display_name, title, max_width, SCALE1(BUTTON_PADDING * 2));
                 max_width = MIN(max_width, text_width);
 
                 SDL_Surface *text;
-                text = TTF_RenderUTF8_Blended(font.large, title, COLOR_WHITE);
+                text = TTF_RenderUTF8_Blended(GFX_getFonts()->large, title, COLOR_WHITE);
 
-                GFX_blitPill(ASSET_BLACK_PILL, screen, &(SDL_Rect){SCALE1(PADDING), SCALE1(PADDING), max_width, SCALE1(PILL_SIZE)});
-                SDL_BlitSurface(text, &(SDL_Rect){0, 0, max_width - SCALE1(BUTTON_PADDING * 2), text->h}, screen, &(SDL_Rect){SCALE1(PADDING + BUTTON_PADDING), SCALE1(PADDING + 4)});
+                SDL_Rect title_pill = {SCALE1(PADDING), SCALE1(PADDING), max_width, SCALE1(PILL_SIZE)};
+                GFX_blitPill(ASSET_BLACK_PILL, screen, &title_pill);
+                SDL_Rect title_src = {0, 0, max_width - SCALE1(BUTTON_PADDING * 2), text->h};
+                SDL_Rect title_dst = {SCALE1(PADDING + BUTTON_PADDING), SCALE1(PADDING + 4)};
+                SDL_BlitSurface(text, &title_src, screen, &title_dst);
                 SDL_FreeSurface(text);
             }
 
             renderPage();
 
             if (show_setting)
                 GFX_blitHardwareHints(screen, show_setting);
-            else
-                GFX_blitButtonGroup((char *[]){"L/R", "SCROLL", "L1/R1", "ZOOM", NULL}, 0, screen, 0);
+            else {
+                // Named local array: g++ 8.3 miscompiles a (char*[]){...} compound
+                // literal passed straight to a function.
+                const char* hints_scroll[] = {"L/R", "SCROLL", "L1/R1", "ZOOM", NULL};
+                GFX_blitButtonGroup((char**)hints_scroll, 0, screen, 0);
+            }
 
-            GFX_blitButtonGroup((char *[]){"B", "BACK", NULL}, 1, screen, 1);
+            const char* hints_back[] = {"B", "BACK", NULL};
+            GFX_blitButtonGroup((char**)hints_back, 1, screen, 1);
 
             GFX_flip(screen);
             dirty = 0;

workspace/all/battery/makefile

@@ -21,18 +21,29 @@ SDL?=SDL
 
 TARGET = battery
 INCDIR = -I. -I../common/ -I../../$(PLATFORM)/platform/
-SOURCE = $(TARGET).c ../common/utils.c ../common/api.c ../common/config.c ../common/scaler.c ../../$(PLATFORM)/platform/platform.c
+# Shared common/ + platform stay C; the tool itself is C++20. Compile the C
+# units to objects, then compile the .cpp and link everything through g++.
+SOURCE = -c ../../$(PLATFORM)/platform/platform.cpp
+CXXSOURCE = $(TARGET).cpp ../common/utils.cpp ../common/config.cpp ../common/scaler.cpp ../common/api.cpp
+CXXSOURCE += build/$(PLATFORM)/platform.o
 
 CC = $(CROSS_COMPILE)gcc
+CXX = $(CROSS_COMPILE)g++
+# Prefer real C++20; fall back to gnu++2a on older toolchains (e.g. the current
+# gcc 8.3 tg5040 cross-compiler, which predates the -std=gnu++20 spelling).
+CXXSTD := $(shell printf 'int main(){return 0;}' | $(CXX) -std=gnu++20 -x c++ - -o /dev/null >/dev/null 2>&1 && echo gnu++20 || echo gnu++2a)
 CFLAGS  += $(OPT)
-CFLAGS  += $(INCDIR) -DPLATFORM=\"$(PLATFORM)\" -std=gnu99
+CFLAGS  += $(INCDIR) -DPLATFORM=\"$(PLATFORM)\"
+CXXFLAGS += $(CFLAGS) -std=$(CXXSTD)
 LDFLAGS	 += -lmsettings -lbatmondb -lsqlite3
 
 PRODUCT= build/$(PLATFORM)/$(TARGET).elf
 
 all: $(PREFIX_LOCAL)/include/batmondb.h
 	mkdir -p build/$(PLATFORM)
-	$(CC) $(SOURCE) -o $(PRODUCT) $(CFLAGS) $(LDFLAGS)
+	$(CXX) $(SOURCE) $(CXXFLAGS) $(LDFLAGS)
+	mv platform.o build/$(PLATFORM)
+	$(CXX) $(CXXSOURCE) -o $(PRODUCT) $(CXXFLAGS) $(LDFLAGS) -lstdc++
 clean:
 	rm -f $(PRODUCT)
 

workspace/all/bootlogo/bootlogo.c → workspace/all/bootlogo/bootlogo.cpp

@@ -1,14 +1,17 @@
-#include <stdio.h>
+#include <cstdio>
 #include <unistd.h>
-#include <stdbool.h>
-#include <stdlib.h>
+#include <cstdlib>
 #include <dirent.h>
 #include <signal.h>
-#include <msettings.h>
 
+// Project + libmsettings C headers declare C-linkage symbols defined in the
+// still-C common/ and libmsettings translation units; include as extern "C".
+extern "C" {
+#include <msettings.h>
 #include "defines.h"
 #include "api.h"
 #include "utils.h"
+}
 
 static bool quit = false;
 
@@ -57,9 +60,9 @@ int loadImages()
                 SDL_Surface *bmp = IMG_Load(path);
                 if (bmp) {
                     count++;
-                    images = realloc(images, sizeof(SDL_Surface*) * count);
+                    images = (SDL_Surface**)realloc(images, sizeof(SDL_Surface*) * count);
                     images[count-1] = bmp;
-                    image_paths = realloc(image_paths, sizeof(char*) * count);
+                    image_paths = (char**)realloc(image_paths, sizeof(char*) * count);
                     image_paths[count-1] = strdup(path);
                 }
             }
@@ -140,7 +143,7 @@ int main(int argc, char *argv[])
                 // sync
                 // umount $BOOT_PATH
                 // reboot
-                char* boot_path = "/mnt/boot/";
+                const char* boot_path = "/mnt/boot/";
                 char* logo_path = image_paths[selected];
                 char cmd[256]; 
                 snprintf(cmd, sizeof(cmd), "mkdir -p %s && mount -t vfat /dev/mmcblk0p1 %s && cp \"%s\" %s/bootlogo.bmp && sync && umount %s && reboot", boot_path, boot_path, logo_path, boot_path, boot_path);
@@ -179,8 +182,12 @@ int main(int argc, char *argv[])
                 SDL_BlitSurface(image, NULL, screen, &image_rect);
             }
 
-            GFX_blitButtonGroup((char *[]){"L/R", "SCROLL", NULL}, 0, screen, 0);
-            GFX_blitButtonGroup((char *[]){"A", "SET", "B", "BACK", NULL}, 1, screen, 1);
+            // Route button hints through named local arrays: g++ 8.3 miscompiles
+            // a (char*[]){...} compound literal passed straight to a function.
+            const char* hints_scroll[] = {"L/R", "SCROLL", NULL};
+            GFX_blitButtonGroup((char**)hints_scroll, 0, screen, 0);
+            const char* hints_set[] = {"A", "SET", "B", "BACK", NULL};
+            GFX_blitButtonGroup((char**)hints_set, 1, screen, 1);
 
             GFX_flip(screen);
             dirty = 0;

workspace/all/bootlogo/makefile

@@ -21,18 +21,29 @@ SDL?=SDL
 
 TARGET = bootlogo
 INCDIR = -I. -I../common/ -I../../$(PLATFORM)/platform/
-SOURCE = $(TARGET).c ../common/utils.c ../common/api.c ../common/config.c ../common/scaler.c ../../$(PLATFORM)/platform/platform.c
+# Shared common/ + platform stay C; the tool itself is C++20. Compile the C
+# units to objects, then compile the .cpp and link everything through g++.
+SOURCE = -c ../../$(PLATFORM)/platform/platform.cpp
+CXXSOURCE = $(TARGET).cpp ../common/utils.cpp ../common/config.cpp ../common/scaler.cpp ../common/api.cpp
+CXXSOURCE += build/$(PLATFORM)/platform.o
 
 CC = $(CROSS_COMPILE)gcc
+CXX = $(CROSS_COMPILE)g++
+# Prefer real C++20; fall back to gnu++2a on older toolchains (e.g. the current
+# gcc 8.3 tg5040 cross-compiler, which predates the -std=gnu++20 spelling).
+CXXSTD := $(shell printf 'int main(){return 0;}' | $(CXX) -std=gnu++20 -x c++ - -o /dev/null >/dev/null 2>&1 && echo gnu++20 || echo gnu++2a)
 CFLAGS  += $(OPT)
-CFLAGS  += $(INCDIR) -DPLATFORM=\"$(PLATFORM)\" -std=gnu99
+CFLAGS  += $(INCDIR) -DPLATFORM=\"$(PLATFORM)\"
+CXXFLAGS += $(CFLAGS) -std=$(CXXSTD)
 LDFLAGS	 += -lmsettings
 
 PRODUCT= build/$(PLATFORM)/$(TARGET).elf
 
 all: $(PREFIX_LOCAL)/include/msettings.h
 	mkdir -p build/$(PLATFORM)
-	$(CC) $(SOURCE) -o $(PRODUCT) $(CFLAGS) $(LDFLAGS)
+	$(CXX) $(SOURCE) $(CXXFLAGS) $(LDFLAGS)
+	mv platform.o build/$(PLATFORM)
+	$(CXX) $(CXXSOURCE) -o $(PRODUCT) $(CXXFLAGS) $(LDFLAGS) -lstdc++
 clean:
 	rm -f $(PRODUCT)