From f47892c133b94811e0e1f6551820cdb898c0093c Mon Sep 17 00:00:00 2001
From: Ry <ryanst755@gmail.com>
Date: Mon, 6 Mar 2023 17:29:06 -0800
Subject: [PATCH] kernel/main: Add a fox32rom API version check

---
 fox32os.def     |  5 +++--
 kernel/main.asm | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/fox32os.def b/fox32os.def
index 2cbb526..cd12f41 100644
--- a/fox32os.def
+++ b/fox32os.def
@@ -2,8 +2,9 @@
 
 ; system jump table
 get_os_version:            jmp [0x00000810]
-get_current_disk_id:       jmp [0x00000814]
-set_current_disk_id:       jmp [0x00000818]
+get_os_api_version:        jmp [0x00000814]
+get_current_disk_id:       jmp [0x00000818]
+set_current_disk_id:       jmp [0x0000081C]
 
 ; FXF jump table
 parse_fxf_binary:          jmp [0x00000910]
diff --git a/kernel/main.asm b/kernel/main.asm
index def282e..2a65aa9 100644
--- a/kernel/main.asm
+++ b/kernel/main.asm
@@ -6,6 +6,10 @@ const FOX32OS_VERSION_MAJOR: 0
 const FOX32OS_VERSION_MINOR: 1
 const FOX32OS_VERSION_PATCH: 1
 
+const FOX32OS_API_VERSION: 1
+
+const REQUIRED_FOX32ROM_API_VERSION: 1
+
 const SYSTEM_STACK:     0x01FFF800
 const BACKGROUND_COLOR: 0xFF674764
 const TEXT_COLOR:       0xFFFFFFFF
@@ -16,6 +20,7 @@ const TEXT_COLOR:       0xFFFFFFFF
     org.pad 0x00000010
 jump_table:
     data.32 get_os_version
+    data.32 get_os_api_version
     data.32 get_current_disk_id
     data.32 set_current_disk_id
 
@@ -99,6 +104,16 @@ entry_ok:
     mov r0, BACKGROUND_COLOR
     call fill_background
 
+    ; check for the required fox32rom API version
+    mov r0, get_rom_api_version
+    add r0, 2
+    mov r0, [r0]
+    cmp [r0], 0
+    ifz jmp api_version_too_low_error
+    call get_rom_api_version
+    cmp r0, REQUIRED_FOX32ROM_API_VERSION
+    iflt jmp api_version_too_low_error
+
     ; initialize the memory allocator
     call initialize_allocator
 
@@ -333,6 +348,21 @@ memory_error:
     call draw_format_str_to_background
     rjmp 0
 
+api_version_too_low_error:
+    mov r0, BACKGROUND_COLOR
+    call fill_background
+
+    mov r0, api_error_str
+    mov r1, 16
+    mov r2, 464
+    mov r3, TEXT_COLOR
+    mov r4, 0x00000000
+    mov r10, FOX32OS_VERSION_MAJOR
+    mov r11, FOX32OS_VERSION_MINOR
+    mov r12, FOX32OS_VERSION_PATCH
+    call draw_format_str_to_background
+    rjmp 0
+
 get_current_disk_id:
     movz.8 r0, [current_disk_id]
     ret
@@ -347,6 +377,10 @@ get_os_version:
     mov r2, FOX32OS_VERSION_PATCH
     ret
 
+get_os_api_version:
+    mov r0, FOX32OS_API_VERSION
+    ret
+
     #include "allocator.asm"
     #include "fxf/fxf.asm"
     #include "task.asm"
@@ -359,6 +393,7 @@ bottom_bar_str_1: data.strz "32"
 bottom_bar_str_2: data.strz " OS version %u.%u.%u "
 startup_error_str: data.strz "fox32 - OS version %u.%u.%u - startup.cfg is invalid!"
 memory_error_str: data.strz "fox32 - OS version %u.%u.%u - not enough memory to perform operation!"
+api_error_str: data.strz "fox32 - OS version %u.%u.%u - fox32rom API version too low!"
 kernelception_error_str: data.strz "Error: kernelception?"
 bottom_bar_patterns:
     ; 1x16 tile