From 0af29f26ae69ba0ba9c5088612f0c537a20c0344 Mon Sep 17 00:00:00 2001
From: Daniel Liu <mr.picklepinosaur@gmail.com>
Date: Sat, 19 Jun 2021 14:54:18 -0400
Subject: [PATCH] starting on repl

---
 fileutils.S   |  1 +
 fileutils.asm | 12 ++++++--
 sped.asm      | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 92 insertions(+), 2 deletions(-)

diff --git a/fileutils.S b/fileutils.S
index 178bca4..7ce6be3 100644
--- a/fileutils.S
+++ b/fileutils.S
@@ -3,5 +3,6 @@
 %define __FILEUTILS_S__
 
 extern readFile
+extern readLine
 
 %endif
diff --git a/fileutils.asm b/fileutils.asm
index 1d96aa0..0f829f5 100644
--- a/fileutils.asm
+++ b/fileutils.asm
@@ -6,6 +6,7 @@ extern free
 extern memset
 
 global readFile
+global readLine
 
 section .data
     wrongfile_str db `unable to open file, error code: %i\n`, 0x00
@@ -65,8 +66,8 @@ readFile:
     mov esi, eax
     mov [ebp-IS_EOF], ebx
     
-    push esi
-    call printf
+    ; push esi
+    ; call printf
 
     ; make string buffer bigger
     mov eax, DWORD [ebp-LINES_READ]
@@ -113,6 +114,7 @@ readFile:
 ; return:
 ;   eax: location to buffer
 ;   ebx: contains eof
+;   ecx: number of chars read
 readLine:
     %define _FILE_HANDLE 8
     %define CHAR_COUNT   4   ; count number of characters read
@@ -178,6 +180,12 @@ readLine:
 
     _readLine_exit:
 
+    mov eax, [ebp-BLOCK_COUNT]
+    mov ecx, 63
+    mul ecx
+    add eax, [ebp-CHAR_COUNT]
+    mov ecx,eax
+
     mov eax, DWORD [ebp-STR_PTR]
 
     %undef _FILE_HANDLE
diff --git a/sped.asm b/sped.asm
index 110bf98..1e20038 100644
--- a/sped.asm
+++ b/sped.asm
@@ -5,10 +5,29 @@
 
 global main
 extern printf
+extern fflush
+extern stdout
+
+; macros
+%macro write_str 2
+    mov eax, 4
+    mov ebx, 1
+    mov ecx, %1
+    mov edx, %2
+    int 0x80
+%endmacro
 
 section .data
     banner_str db `SPED - the stupidly pointless editor\n`, 0x00
     nofile_str db `no file provided\n`, 0x00
+    prompt_str db `sped > `, 0x00
+    invalidcommand_str db `invalid command\n`, 0x00
+    charcount_str db `read %i chars\n`, 0x00
+
+section .bss
+    buffer resb 4
+    buffer_lines resb 4
+    cur_line resb 4
 
 section .text
 main:
@@ -35,6 +54,12 @@ main:
     push DWORD [ebx]
     call readFile
 
+    mov [buffer], eax
+    mov [buffer_lines], ebx
+    mov DWORD [cur_line], 0x00
+
+    call repl
+
     mov eax, 0
     jmp _main_exit
 
@@ -46,3 +71,59 @@ main:
     pop ebp
     ret
 
+; prompt for user
+; no args - reads from globals
+repl:
+
+    %define CMDSTR 4 ; the previous line read from user
+
+    push ebp
+    mov ebp, esp
+
+    sub esp, 4
+
+    _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
+
+    ; 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:
+
+
+    _repl_invalid:
+    push invalidcommand_str
+    call printf
+
+    _repl_continue:
+    jmp _repl_loop
+    
+    _repl_exit:
+
+    %undef CMDSTR
+
+    mov esp, ebp
+    pop ebp
+    ret
+    
-- 
2.20.1