Fix snapshot save/load: route both through CPU trap to sync registers

machine_write_snapshot reads maincpu_regs.pc to record the current program counter. When called directly from video_canvas_refresh, maincpu_regs is stale — the CPU loop keeps registers as stack-local variables and only syncs them to maincpu_regs inside DO_INTERRUPT via EXPORT_REGISTERS(). The snapshot therefore recorded the wrong PC. On restore (already trap-based), the wrong PC was faithfully written back into reg_pc via IMPORT_REGISTERS(), causing the CPU to resume at a bad address. The game screen looked correct (memory/VIC/SID state all restored) but the CPU never reached the input-polling code, so button presses had no effect. Fix: route machine_write_snapshot through interrupt_maincpu_trigger_trap so DO_INTERRUPT(IK_TRAP) calls EXPORT_REGISTERS() before the trap function, capturing the true current PC before the snapshot is written.
2026-06-17 20:50:51 +02:00
parent b9153ac973
commit 463c85e62f
33 changed files with 85 additions and 220 deletions
@@ -32,7 +32,10 @@ if(HAVE_VICE)
        -Wl,--wrap=ui_display_drive_led
        -Wl,--wrap=serial_trap_receive
        -Wl,--wrap=event_snapshot_write_module
-        -Wl,--wrap=event_snapshot_read_module)
+        -Wl,--wrap=event_snapshot_read_module
        -Wl,--wrap=machine_trigger_reset
        -Wl,--wrap=machine_reset
        -Wl,--wrap=maincpu_reset)
    target_include_directories(vice_jni PRIVATE
        "${CMAKE_CURRENT_SOURCE_DIR}/vice-libs/${ANDROID_ABI}"
        "${VICE_SRC}/src"
@@ -77,6 +77,7 @@ extern int  __real_console_init(void);
 #include "keyboard.h"
 #include "autostart.h"
 #include "attach.h"
 #include "interrupt.h"
 /* Drive LED state.
 * g_io_frames: bumped by __wrap_serial_trap_receive; keeps LED lit ~100 ms after
@@ -302,6 +303,69 @@ int __wrap_event_snapshot_read_module(struct snapshot_s *s) {
    (void)s; return 0;
 }
 /* --wrap=machine_trigger_reset / machine_reset / maincpu_reset: required by the
 * linker --wrap flags in CMakeLists.txt; kept as simple pass-throughs so the
 * symbols exist.  Previously these suppressed resets during snapshot load, but
 * the trap-based snapshot load (see load_state_trap below) makes suppression
 * unnecessary — snapshot load now runs inside DO_INTERRUPT(IK_TRAP) which
 * provides the EXPORT/IMPORT register sync that makes the CPU resume from the
 * correct saved PC without any post-load machine reset. */
 void __real_machine_trigger_reset(unsigned int reset_mode);
 void __wrap_machine_trigger_reset(unsigned int reset_mode) {
    __real_machine_trigger_reset(reset_mode);
 }
 void __real_machine_reset(void);
 void __wrap_machine_reset(void) {
    __real_machine_reset();
 }
 void __real_maincpu_reset(void);
 void __wrap_maincpu_reset(void) {
    __real_maincpu_reset();
 }
 /* Snapshot load via VICE CPU trap.
 *
 * machine_read_snapshot() restores CPU registers into maincpu_regs (a global
 * struct), but maincpu_mainloop keeps its own stack-local copies (reg_pc,
 * reg_a, etc.).  If we call machine_read_snapshot() directly from
 * video_canvas_refresh(), the loop never re-imports maincpu_regs, so the CPU
 * continues from the *old* reg_pc in the *new* (restored) memory — wrong.
 *
 * The fix: schedule a VICE CPU trap.  DO_INTERRUPT(IK_TRAP) in 6510core.c
 * calls EXPORT_REGISTERS() before the trap function and IMPORT_REGISTERS()
 * after.  machine_read_snapshot() inside the trap overwrites maincpu_regs
 * with the saved state; IMPORT_REGISTERS() then propagates those values
 * (including the saved PC) back into the CPU loop's stack locals.  Result:
 * the game resumes from exactly the saved execution point. */
 /* Both save and load run inside a CPU trap so DO_INTERRUPT(IK_TRAP) calls
 * EXPORT_REGISTERS() before the trap function and IMPORT_REGISTERS() after.
 *
 * For save: EXPORT_REGISTERS() syncs the CPU loop's stack-local reg_pc into
 * maincpu_regs before machine_write_snapshot reads it.  Without the trap,
 * maincpu_regs.pc is stale (last synced at the previous DO_INTERRUPT), so the
 * snapshot would record the wrong PC and restore would resume at the wrong
 * address — input polling code never reached, buttons appear dead.
 *
 * For load: machine_read_snapshot overwrites maincpu_regs with the saved state;
 * IMPORT_REGISTERS() then propagates the saved PC back into reg_pc so the CPU
 * resumes from the correct saved execution point. */
 static char g_save_trap_path[512] = {0};
 static char g_load_trap_path[512] = {0};
 static void save_state_trap(uint16_t address, void *data) {
    (void)address;
    int r = machine_write_snapshot((const char *)data, 0, 0, 0);
    LOGI("machine_write_snapshot → %d", r);
 }
 static void load_state_trap(uint16_t address, void *data) {
    (void)address;
    int r = machine_read_snapshot((const char *)data, 0);
    LOGI("machine_read_snapshot → %d", r);
 }
 /* All functions below replace arch/headless/video.c (excluded from libvice.a). */
 int  video_arch_get_active_chip(void)              { return 0; /* VIDEO_CHIP_VICII */ }
@@ -425,19 +489,19 @@ void video_canvas_refresh(video_canvas_t *canvas,
    }
    pthread_mutex_unlock(&g_pending_lock);
    if (save_state_path[0] != '\0') {
-        /* save_roms=0, save_disks=0: disk management is handled by our UI;
+        strncpy(g_save_trap_path, save_state_path, sizeof(g_save_trap_path) - 1);
-         * skipping the drive module avoids path-resolution failures on restore. */
+        g_save_trap_path[sizeof(g_save_trap_path) - 1] = '\0';
-        int r = machine_write_snapshot(save_state_path, 0, 0, 0);
+        interrupt_maincpu_trigger_trap(save_state_trap, g_save_trap_path);
        LOGI("machine_write_snapshot → %d", r);
    }
    if (load_state_path[0] != '\0') {
-        int r = machine_read_snapshot(load_state_path, 0);
+        /* Schedule a VICE CPU trap so machine_read_snapshot runs inside
-        LOGI("machine_read_snapshot → %d", r);
+         * DO_INTERRUPT(IK_TRAP).  That macro calls EXPORT_REGISTERS() before
-        /* After snapshot restore the virtual device loses its D64 attachment
+         * the trap and IMPORT_REGISTERS() after, so the saved PC written into
-         * and falls back to host-filesystem mode.  Re-attach the same disk so
+         * maincpu_regs by machine_read_snapshot is picked up by the CPU loop
-         * the C64 program can continue reading from the image it expected. */
+         * immediately — the game resumes from the correct saved execution point. */
-        if (r == 0 && g_current_disk_path[0] != '\0')
+        strncpy(g_load_trap_path, load_state_path, sizeof(g_load_trap_path) - 1);
-            file_system_attach_disk(8, 0, g_current_disk_path);
+        g_load_trap_path[sizeof(g_load_trap_path) - 1] = '\0';
        interrupt_maincpu_trigger_trap(load_state_trap, g_load_trap_path);
    }
    /* Drive LED.
@@ -1,170 +0,0 @@
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@@ -1,30 +0,0 @@
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@@ -1,6 +1,5 @@
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-    <background android:drawable="@drawable/ic_launcher_background" />
+    <background android:drawable="@android:color/transparent"/>
-    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+    <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
-    <monochrome android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>
 </adaptive-icon>
@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
-    <background android:drawable="@drawable/ic_launcher_background" />
+    <background android:drawable="@android:color/transparent"/>
-    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+    <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
-    <monochrome android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>
 </adaptive-icon>