310 lines
6.9 KiB
NASM
310 lines
6.9 KiB
NASM
; shell routines
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const CURSOR: 138
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; create a new shell task
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; inputs:
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; r0: task ID
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; r1: pointer to stream struct
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; outputs:
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; none
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new_shell_task:
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push r0
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push r1
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push r2
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push r3
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push r4
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push r10
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; allocate a 64KiB stack and push the pointer to the stream struct to it
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push r0
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push r1
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mov r0, 65536
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call allocate_memory
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add r0, 65532
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pop r1
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mov [r0], r1
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mov r10, r0
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pop r0
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; then start the task
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mov r1, shell_task ; initial instruction pointer
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mov r2, r10 ; initial stack pointer
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mov r3, 0 ; pointer to task code block to free when task ends
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; (zero since we don't want to free any code blocks when the task ends)
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mov r4, r10 ; pointer to task stack block to free when task ends
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sub r4, 65536 ; point to the start of the stack block that we allocated above
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call new_task
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pop r10
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pop r4
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pop r3
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pop r2
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pop r1
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pop r0
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ret
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; print a character to the terminal
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; inputs:
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; r0: ASCII character
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; outputs:
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; none
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print_character_to_terminal:
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push r1
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push r2
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mov.8 [shell_char_buffer], r0
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mov r1, [shell_terminal_stream_struct_ptr]
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mov r2, shell_char_buffer
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call write
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pop r2
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pop r1
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ret
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; print a string to the terminal
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; inputs:
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; r0: pointer to null-terminated string
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; outputs:
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; none
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print_str_to_terminal:
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push r0
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push r2
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mov r1, [shell_terminal_stream_struct_ptr]
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mov r2, r0
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print_str_to_terminal_loop:
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call write
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inc r2
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cmp.8 [r2], 0x00
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ifnz jmp print_str_to_terminal_loop
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pop r2
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pop r0
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ret
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shell_task:
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pop [shell_terminal_stream_struct_ptr]
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shell_task_return:
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call shell_clear_buffer
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call shell_print_prompt
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shell_task_loop:
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mov r1, [shell_terminal_stream_struct_ptr]
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mov r2, shell_char_buffer
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call read
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movz.8 r0, [shell_char_buffer]
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cmp.8 r0, 0
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ifnz call shell_task_parse_key
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call yield_task
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rjmp shell_task_loop
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shell_task_parse_key:
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; first, check if enter, delete, or backspace was pressed
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cmp.8 r0, 0x1C ; enter
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ifz jmp shell_key_down_enter
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cmp.8 r0, 0x6F ; delete
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ifz jmp shell_key_down_backspace
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cmp.8 r0, 0x0E ; backspace
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ifz jmp shell_key_down_backspace
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; then, overwrite the cursor
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mov r1, r0
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mov r0, 8 ; backspace character
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call print_character_to_terminal
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mov r0, r1
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; then, add it to the text buffer and print it to the screen
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call scancode_to_ascii
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call print_character_to_terminal
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call shell_push_character
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; finally, print the cursor
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mov r0, CURSOR
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call print_character_to_terminal
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ret
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shell_key_down_enter:
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; clear the cursor from the screen
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mov r0, 8 ; backspace character
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call print_character_to_terminal
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mov r0, ' ' ; space character
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call print_character_to_terminal
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mov r0, 8 ; backspace character
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call print_character_to_terminal
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mov r0, 10 ; line feed
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call print_character_to_terminal
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mov r0, 0
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call shell_push_character
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call shell_parse_line
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call shell_clear_buffer
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call shell_print_prompt
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ret
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shell_key_down_backspace:
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; check if we are already at the start of the prompt
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mov r1, [shell_text_buf_ptr]
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cmp r1, shell_text_buf_bottom
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iflteq ret
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; delete the last character from the screen, draw the cursor, and pop the last character from the buffer
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mov r0, 8 ; backspace character
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call print_character_to_terminal
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mov r0, ' ' ; space character
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call print_character_to_terminal
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mov r0, 8 ; backspace character
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call print_character_to_terminal
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call print_character_to_terminal
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mov r0, CURSOR ; cursor
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call print_character_to_terminal
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call shell_delete_character
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ret
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shell_print_prompt:
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movz.8 r0, [shell_current_disk]
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add r0, '0'
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call print_character_to_terminal
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mov r0, shell_prompt
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call print_str_to_terminal
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ret
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shell_parse_line:
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; if the line is empty, just return
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cmp.8 [shell_text_buf_bottom], 0
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ifz ret
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; separate the command from the arguments
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; store the pointer to the arguments
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mov r0, shell_text_buf_bottom
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mov r1, ' '
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call shell_tokenize
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mov [shell_args_ptr], r0
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call shell_parse_command
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ret
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; return tokens separated by the specified character
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; returns the next token in the list
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; inputs:
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; r0: pointer to null-terminated string
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; r1: separator character
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; outputs:
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; r0: pointer to next token or zero if none
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shell_tokenize:
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cmp.8 [r0], r1
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ifz jmp shell_tokenize_found_token
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cmp.8 [r0], 0
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ifz mov r0, 0
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ifz ret
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inc r0
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jmp shell_tokenize
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shell_tokenize_found_token:
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mov.8 [r0], 0
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inc r0
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ret
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; parse up to 4 arguments into individual strings
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; for example, "this is a test" will be converted to
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; r0: pointer to "this" data.8 0
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; r1: pointer to "is" data.8 0
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; r2: pointer to "a" data.8 0
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; r3: pointer to "test" data.8 0
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; inputs:
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; none
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; outputs:
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; r0: pointer to 1st null-terminated argument, or zero if none
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; r1: pointer to 2nd null-terminated argument, or zero if none
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; r2: pointer to 3rd null-terminated argument, or zero if none
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; r3: pointer to 4th null-terminated argument, or zero if none
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shell_parse_arguments:
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push r31
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mov r0, [shell_args_ptr]
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mov r1, ' '
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mov r31, 3
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push r0
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shell_parse_arguments_loop:
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call shell_tokenize
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push r0
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loop shell_parse_arguments_loop
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pop r3
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pop r2
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pop r1
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pop r0
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pop r31
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ret
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; push a character to the text buffer
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; inputs:
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; r0: character
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; outputs:
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; none
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shell_push_character:
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push r1
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mov r1, [shell_text_buf_ptr]
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cmp r1, shell_text_buf_top
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ifgteq jmp shell_push_character_end
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mov.8 [r1], r0
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inc [shell_text_buf_ptr]
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shell_push_character_end:
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pop r1
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ret
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; pop a character from the text buffer and zero it
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; inputs:
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; none
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; outputs:
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; r0: character
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shell_delete_character:
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push r1
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mov r1, [shell_text_buf_ptr]
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cmp r1, shell_text_buf_bottom
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iflteq jmp shell_delete_character_end
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dec [shell_text_buf_ptr]
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movz.8 r0, [r1]
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mov.8 [r1], 0
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shell_delete_character_end:
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pop r1
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ret
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; mark the text buffer as empty
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; inputs:
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; none
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; outputs:
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; none
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shell_clear_buffer:
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push r0
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; set the text buffer poinrer to the start of the text buffer
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mov [shell_text_buf_ptr], shell_text_buf_bottom
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; set the first character as null
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mov r0, [shell_text_buf_ptr]
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mov.8 [r0], 0
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pop r0
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ret
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shell_text_buf_bottom: data.fill 0, 512
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shell_text_buf_top:
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shell_text_buf_ptr: data.32 0 ; pointer to the current input character
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shell_args_ptr: data.32 0 ; pointer to the beginning of the command arguments
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shell_current_disk: data.8 0
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shell_prompt: data.str "> " data.8 CURSOR data.8 0
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shell_terminal_stream_struct_ptr: data.32 0
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shell_char_buffer: data.32 0
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#include "shell/commands/commands.asm"
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#include "shell/launch.asm"
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