[msdos] add appkey support

Changelog.md

@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+- [msdos] Add appkey support [Eric Carr]
+
 ## [4.9.0] 2025-11-23
 
 - [coco] Implemented fuji_copy_file (Rich Stephens)

msdos/src/fn_fuji/fuji_read_appkey.c

@@ -3,8 +3,42 @@
 #include "fujinet-fuji.h"
 #include "fujinet-fuji-msdos.h"
 
+typedef struct _appkey
+{
+    unsigned short creator_id;
+    unsigned char app_id;
+    unsigned char key_id;
+    unsigned char open_mode;
+    unsigned char reserved;
+} Appkey;
+
+extern uint16_t ak_creator_id;
+extern uint8_t ak_app_id;
+extern uint8_t ak_appkey_size; 
+Appkey appkey;
+
 bool fuji_read_appkey(uint8_t key_id, uint16_t *count, uint8_t *data)
 {
-    // FIXME Implement.
-    return true;
+    short result;
+
+    // Setup full appkey identifier
+    appkey.creator_id = ak_creator_id;
+    appkey.app_id = ak_app_id;
+    appkey.key_id = key_id;
+    appkey.open_mode = 0; // read
+    appkey.reserved = 0;
+
+    // Open app key
+    int_f5_write(0x70,FUJICMD_OPEN_APPKEY,0,0,&appkey,sizeof(appkey));
+
+    // Read app key data
+    if (int_f5_read(0x70,FUJICMD_READ_APPKEY,0,0,data,66)) {
+        *count = *(uint16_t*)data;
+        memcpy(data,data+2, 64);
+        return true;
+    } else {
+        count=0;
+    }
+    return false;
+
 }

msdos/src/fn_fuji/fuji_write_appkey.c

@@ -3,8 +3,32 @@
 #include "fujinet-fuji.h"
 #include "fujinet-fuji-msdos.h"
 
+typedef struct _appkey
+{
+    unsigned short creator_id;
+    unsigned char app_id;
+    unsigned char key_id;
+    unsigned char open_mode;
+    unsigned char reserved;
+} Appkey;
+
+extern uint16_t ak_creator_id;
+extern uint8_t ak_app_id;
+extern uint8_t ak_appkey_size; 
+extern Appkey appkey;
+
 bool fuji_write_appkey(uint8_t key_id, uint16_t count, uint8_t *data)
 {
-    // not implemented.
-    return true;
+    // Setup full appkey identifier
+    appkey.creator_id = ak_creator_id;
+    appkey.app_id = ak_app_id;
+    appkey.key_id = key_id;
+    appkey.open_mode = 1; // write
+    appkey.reserved = 0;
+
+    // Open app key
+    int_f5_write(0x70,FUJICMD_OPEN_APPKEY,0,0,&appkey,sizeof(appkey));
+
+    // Write data to app key
+    return int_f5_write(0x70,FUJICMD_WRITE_APPKEY,64,0,data,64) > 0;
 }