From c6919d4168e039c7704b65bbcd29a6213a8abf4b Mon Sep 17 00:00:00 2001
From: Ry <ryanst755@gmail.com>
Date: Fri, 25 Nov 2022 17:21:28 -0800
Subject: [PATCH] shell: Add `clear` command

---
 kernel/shell/commands/clear.asm    | 22 ++++++++++++++++++++++
 kernel/shell/commands/commands.asm |  6 ++++++
 kernel/shell/commands/help.asm     |  1 +
 3 files changed, 29 insertions(+)
 create mode 100644 kernel/shell/commands/clear.asm

diff --git a/kernel/shell/commands/clear.asm b/kernel/shell/commands/clear.asm
new file mode 100644
index 0000000..4fd1069
--- /dev/null
+++ b/kernel/shell/commands/clear.asm
@@ -0,0 +1,22 @@
+; clear command
+
+const FILL_TERM: 0xF0
+const MOVE_CURSOR: 0xF1
+
+shell_clear_command_string: data.str "clear" data.8 0
+
+shell_clear_command:
+    movz.8 r0, FILL_TERM
+    call print_character_to_terminal
+    movz.8 r0, 0
+    call print_character_to_terminal
+    call print_character_to_terminal
+
+    movz.8 r0, MOVE_CURSOR
+    call print_character_to_terminal
+    movz.8 r0, 0
+    call print_character_to_terminal
+    movz.8 r0, 0
+    call print_character_to_terminal
+
+    ret
diff --git a/kernel/shell/commands/commands.asm b/kernel/shell/commands/commands.asm
index d6b976e..af40a13 100644
--- a/kernel/shell/commands/commands.asm
+++ b/kernel/shell/commands/commands.asm
@@ -3,6 +3,11 @@
 shell_parse_command:
     mov r0, shell_text_buf_bottom
 
+    ; clear
+    mov r1, shell_clear_command_string
+    call compare_string
+    ifz jmp shell_clear_command
+
     ; dir
     mov r1, shell_dir_command_string
     call compare_string
@@ -45,6 +50,7 @@ shell_parse_command:
 shell_invalid_command_string: data.str "invalid command or FXF binary" data.8 10 data.8 0
 
     ; all commands
+    #include "shell/commands/clear.asm"
     #include "shell/commands/dir.asm"
     #include "shell/commands/disk.asm"
     #include "shell/commands/diskrm.asm"
diff --git a/kernel/shell/commands/help.asm b/kernel/shell/commands/help.asm
index 4d45a67..2cd8f63 100644
--- a/kernel/shell/commands/help.asm
+++ b/kernel/shell/commands/help.asm
@@ -14,6 +14,7 @@ shell_help_text:
     data.str "(in descriptions, $n is argument n)" data.8 10
     data.str "command | description" data.8 10
     data.str "------- | -----------" data.8 10
+    data.str "clear   | clear the terminal contents" data.8 10
     data.str "dir     | show contents of selected disk" data.8 10
     data.str "disk    | select disk $0" data.8 10
     data.str "diskrm  | remove disk $0" data.8 10