From 737708d2a5e6ec61079236484c0a4c8234206ea8 Mon Sep 17 00:00:00 2001
From: Daniel Liu <mr.picklepinosaur@gmail.com>
Date: Sat, 19 Jun 2021 22:39:02 -0400
Subject: [PATCH] edge cases and more commands

---
 README.md | 12 ++++++++----
 repl.asm  | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 2436d48..7f87c88 100644
--- a/README.md
+++ b/README.md
@@ -3,10 +3,6 @@
 **sped** is a line editor written in x86 assembly. Back in the day, before visual editors, line editors like **ed** were used.
 This is my own stupid and pointless attempt at writing such line editor.
 
-### FEATURES/NON-FEATURES
-
-
-
 ### INSTALLATION
 
 #### Build from source
@@ -29,12 +25,20 @@ to build the project
 
 **c** - change the contents of the current line
 
+**o/O** - insert line after/before current line
+
+**d** - delete current line
+
 **w** - saves file
 
 **q** - exists the program
 
 ### FAQ
 
+**what is the point of this**
+
+obviously, we live in a day and age where we have the comfort of visual editors, so line editors like these have become obsolete. i simply wanted to work on a relatively easy to implement project so i can learn some assembly.
+
 **are you insane**
 
 yes
diff --git a/repl.asm b/repl.asm
index 6a1472f..038bb1a 100644
--- a/repl.asm
+++ b/repl.asm
@@ -15,6 +15,7 @@ section .data
     prompt_str db `sped > `, 0x00
     invalidcmd_str db `invalid command\n`, 0x00
     invalidaddr_str db `invalid address\n`, 0x00
+    oneline_str db `cannot delete line, as there is only one line\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
@@ -195,6 +196,8 @@ repl:
     jne _repl_cmd_delete_end
     
     ; check to make sure we don't have only one line
+    cmp DWORD [buffer_lines], 1
+    jle _repl_oneline
 
     ; delete the line
     push DWORD [buffer]
@@ -205,12 +208,50 @@ repl:
 
     sub DWORD [buffer_lines], 1
 
+    ; if it's the last line, move one down
+    mov eax, DWORD [buffer_lines]
+    cmp DWORD [cur_line], eax
+    jl _repl_continue
+    sub DWORD [cur_line], 1
+
     jmp _repl_continue
     _repl_cmd_delete_end:
 
     ; o appends text after line =-=-=-=-=-=-=-=-=
     mov eax, DWORD [ebp-CMDSTR]
     cmp BYTE [eax], 'o'
+    jne _repl_cmd_appenddown_end
+
+    ; make room first
+    push DWORD [buffer]
+    push DWORD [buffer_lines]
+    mov eax, DWORD [cur_line]
+    add eax, 1
+    push eax
+    call shiftRight
+    mov [buffer], eax
+
+    ; input text
+    push 0
+    call readLine
+    mov esi, eax
+
+    ; insert new string
+    mov eax, [cur_line]
+    add eax, 1
+    mov ecx, 4
+    mul ecx
+    add eax, DWORD [buffer]
+    mov [eax], esi
+
+    add DWORD [buffer_lines], 1
+
+    jmp _repl_continue
+    _repl_cmd_appenddown_end:
+
+    ; O oppens text before line =-=-=-=-=-=-=-=
+    mov eax, DWORD [ebp-CMDSTR]
+    cmp BYTE [eax], 'O'
     jne _repl_cmd_appendup_end
 
     ; make room first
@@ -231,12 +272,16 @@ repl:
     mul ecx
     add eax, DWORD [buffer]
     mov [eax], esi
+    
+    ; also move cursor down one
+    add DWORD [cur_line], 1
 
     add DWORD [buffer_lines], 1
 
     jmp _repl_continue
     _repl_cmd_appendup_end:
 
+
     ; w writes file =-=-=-=-=-=-=-=-=-=-=-=-=
     mov eax, DWORD [ebp-CMDSTR]
     cmp BYTE [eax], 'w'
@@ -265,6 +310,11 @@ repl:
     call printf
     jmp _repl_continue
 
+    _repl_oneline:
+    push oneline_str
+    call printf
+    jmp _repl_continue
+
     _repl_continue:
     jmp _repl_loop
     
-- 
2.20.1