X-Git-Url: https://git.danieliu.xyz/?p=sped.git;a=blobdiff_plain;f=repl.asm;fp=repl.asm;h=3c7f429a9573deace3750cbfe4961eb891e69362;hp=0000000000000000000000000000000000000000;hb=89732d399de9007aaf2894b0c637e8cfb9ed47ac;hpb=7a7ed6ae81978b84911dab0b902e77ebb7e9b735

diff --git a/repl.asm b/repl.asm
new file mode 100644
index 0000000..3c7f429
--- /dev/null
+++ b/repl.asm
@@ -0,0 +1,240 @@
+
+%include "fileutils.S"
+
+extern printf
+extern fflush
+extern stdout
+extern free
+
+global repl
+
+section .data
+    prompt_str db `sped > `, 0x00
+    invalidcmd_str db `invalid command\n`, 0x00
+    invalidaddr_str db `invalid address\n`, 0x00
+    charcount_str db `read %i chars\n`, 0x00
+    currentline_str db `current line: %i\n`, 0x00
+    echo_str db `%s`, 0x00 ; print strings without format exploit
+
+section .bss
+    buffer resb 4
+    buffer_lines resb 4
+    buffer_filename resb 4
+    cur_line resb 4
+
+section .text
+
+; prompt for user
+; args: buffer, buffer_lines, buffer_filename
+repl:
+
+    %define _BUFFER          16
+    %define _BUFFER_LINES    12
+    %define _BUFFER_FILENAME 8
+    %define CMDSTR           4 ; the previous line read from user
+
+    push ebp
+    mov ebp, esp
+
+    sub esp, 4
+    
+    ; set bss vars
+    mov eax, [ebp+_BUFFER]
+    mov [buffer], eax
+    mov eax, [ebp+_BUFFER_LINES]
+    mov [buffer_lines], eax
+    mov eax, [ebp+_BUFFER_FILENAME]
+    mov [buffer_filename], eax
+    mov DWORD [cur_line], 0x00
+
+    _repl_loop:
+    
+    ; print the prompt
+    push prompt_str
+    call printf
+    push DWORD [stdout]
+    call fflush
+
+    ; read line from stdin
+    push 0
+    call readLine
+
+    mov DWORD [ebp-CMDSTR], eax
+
+    ; commands are single char for now
+    cmp ecx, 1 
+    jne _repl_invalid_cmd
+
+    ; parse commands
+    mov eax, DWORD [ebp-CMDSTR]
+    mov eax, [eax]
+
+    ; q exists program =-=-=-=-=-=-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], 'q'
+    jne _repl_cmd_quit_end
+    jmp _repl_exit
+    _repl_cmd_quit_end:
+
+    ; p prints current line =-=-=-=-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], 'p'
+    jne _repl_cmd_print_end
+
+    mov eax, DWORD [cur_line]
+    mov ecx, 4
+    mul ecx
+    add eax, [buffer]
+    push DWORD [eax]
+    push echo_str
+    call printf
+    jmp _repl_continue
+    _repl_cmd_print_end:
+
+    ; n prints the current line number =-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], 'n'
+    jne _repl_cmd_number_end
+
+    push DWORD [cur_line]
+    push currentline_str
+    call printf
+
+    jmp _repl_continue
+    _repl_cmd_number_end:
+
+    ; - goes to prev line =-=-=-=-=-=-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], '-'
+    jne _repl_cmd_decline_end
+
+    ; make sure we are within bounds
+    mov eax, DWORD [cur_line] 
+    sub eax, 1
+    cmp eax, 0
+    jl _repl_invalid_addr
+    
+    sub DWORD [cur_line], 1
+
+    jmp _repl_continue
+    _repl_cmd_decline_end:
+
+    ; + goes to next line =-=-=-=-=-=-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], '+'
+    jne _repl_cmd_incline_end
+
+    ; make sure we are within bounds 
+    mov eax, DWORD [cur_line] 
+    add eax, 1
+    cmp eax, [buffer_lines]
+    jge _repl_invalid_addr
+    
+    add DWORD [cur_line], 1
+
+    jmp _repl_continue
+    _repl_cmd_incline_end:
+
+    ; g goes to first line =-=-=-=-=-=-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], 'g'
+    jne _repl_cmd_jumptop_end
+
+    mov DWORD [cur_line], 0x00
+
+    jmp _repl_continue
+    _repl_cmd_jumptop_end:
+
+    ; G goes to last line =-=-=-=-=-=-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], 'G'
+    jne _repl_cmd_jumpbot_end
+
+    mov eax, DWORD [buffer_lines]
+    sub eax, 1
+    mov DWORD [cur_line], eax
+
+    jmp _repl_continue
+    _repl_cmd_jumpbot_end:
+
+    ; c changes the current line =-=-=-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], 'c'
+    jne _repl_cmd_change_end
+
+    ; read a new line to use
+    push 0
+    call readLine
+
+    mov esi, eax
+
+    ; free old string
+    mov eax, [cur_line]
+    mov ecx, 4
+    mul ecx
+    add eax, [buffer]
+    push DWORD [eax]
+    call free
+
+    ; insert new string
+    mov eax, [cur_line]
+    mov ecx, 4
+    mul ecx
+    add eax, DWORD [buffer]
+    mov [eax], esi
+
+    jmp _repl_continue
+    _repl_cmd_change_end:
+
+    ; d delete line =-=-=-=-=-=-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], 'd'
+    jne _repl_cmd_delete_end
+
+    
+
+    jmp _repl_continue
+    _repl_cmd_delete_end:
+
+    ; w writes file =-=-=-=-=-=-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], 'w'
+    jne _repl_cmd_write_end
+
+    push DWORD [buffer_filename]
+    push DWORD [buffer]
+    push DWORD [buffer_lines]
+    call writeFile
+
+    jmp _repl_continue
+    _repl_cmd_write_end:
+
+
+    ; if no commands were matched, it's an error
+    jmp _repl_invalid_cmd
+
+    ; some error messages
+    _repl_invalid_cmd:
+    push invalidcmd_str
+    call printf
+    jmp _repl_continue
+
+    _repl_invalid_addr:
+    push invalidaddr_str
+    call printf
+    jmp _repl_continue
+
+    _repl_continue:
+    jmp _repl_loop
+    
+    _repl_exit:
+
+    %undef _BUFFER
+    %undef _BUFFER_LINES
+    %undef _BUFFER_FILENAME
+    %undef CMDSTR
+
+    mov esp, ebp
+    pop ebp
+    ret
+