move common stuff to utils file

02/main.s

@@ -1,31 +1,17 @@
 %define BUFF_LIM 32768
 
-%define red_lim 12
-%define green_lim 13
-%define blue_lim 14
-%define limits ((red_lim << 16) | (green_lim << 8) | blue_lim)
-
-;             call #  val  val2
-; int $0x80   eax     eax  edx  -
-;
-; arg1  arg2  arg3  arg4  arg5  arg6  arg7  
-; ebx   ecx   edx   esi   edi   ebp   -
 global _start
 [bits 32]
 [section .text]
+
+%include "utils.s"
+
 _start:
-push 0 ; eof
-mov eax, 5 ; open
 mov ebx, filename
-xor ecx, ecx ; read only
-int 0x80
-mov ebx, eax
-mov eax, 3 ; read
+call open_file
 mov ecx, read_buff
 mov edx, BUFF_LIM
-int 0x80
-test eax,eax
-js exit
+call read_file
 add eax, read_buff
 mov [file_lim], eax
 
@@ -90,77 +76,6 @@ mov eax, [final_value]
 call print_dec
 jmp exit
 
-exit:
-mov eax, 1
-int 0x80    ; exit
-
-; string in esi
-; modifies EAX ESI
-dec_parse:
-push ebx
-push ecx
-push edx
-push edi
-xor eax, eax
-xor ecx, ecx
-xor edi, edi
-mov ebx, 10
-.loop:
-lodsb
-sub al, '0'
-js .dec_done
-cmp al, 9
-jg .dec_done
-xchg edi,eax
-mul ebx
-add edi,eax
-jmp .loop
-.dec_done:
-mov eax,edi
-pop edi
-pop edx
-pop ecx
-pop ebx
-ret
-
-; input in EAX, all regs unmodified
-print_dec:
-pushad ; save regs
-; max 4294967296 is 10 chars
-; round to nearest 32-bit boundary
-sub esp, 12
-; string in ECX, length in EDX
-lea ecx, [esp+11] ; last possible byte
-; check for 0
-test eax, eax
-jz .zero
-mov ebx, 10 ; base 10
-xor esi, esi ; counter
-.div_shit:
-xor edx, edx
-; divide
-div ebx
-dec ecx ; next char
-inc esi
-; store
-add dl, '0'
-mov byte [ecx], dl
-; check if done
-test eax, eax
-jnz .div_shit ; continue
-mov edx, esi ; counter in edx
-jmp .write
-.zero:
-mov byte [ecx], '0'
-mov edx, 1 ; length
-.write:
-mov eax, 4 ; write
-mov ebx, 1 ; stdout
-int 0x80
-add esp, 12 ; restore stack
-popad ; restore regs
-ret
-
 [section .data]
 file_lim: dd 0
 final_value: dd 0

02/utils.s

@@ -0,0 +1,119 @@
+;             call #  val  val2
+; int $0x80   eax     eax  edx  -
+;
+; arg1  arg2  arg3  arg4  arg5  arg6  arg7  
+; ebx   ecx   edx   esi   edi   ebp   -
+
+exit:
+mov eax, 1 ; exit
+int 0x80
+
+; filename in EBX
+; return handle in EBX 
+; read only
+open_file:
+push eax
+push ecx
+mov eax, 5 ; open
+xor ecx, ecx ; read only
+int 0x80
+mov ebx, eax
+pop ecx
+pop eax
+ret
+
+; file handle in EBX
+; buffer in ECX
+; count of bytes to read in EDX
+; return bytes actually read in EAX
+; exits on error
+read_file:
+mov eax, 3 ; read
+int 0x80
+test eax, eax
+js .err
+ret
+.err:
+mov eax, 4 ; write
+mov ebx, 1 ; stdout
+mov ecx, .err_str
+mov edx, 21
+int 0x80
+jmp exit
+.err_str: db `Could not read file.\n`
+
+; string input in ESI
+; value in EAX
+; CF set if none, clear if some
+; ESI set past checked area
+dec_parse:
+push ebx
+push edx
+push edi
+xor eax, eax
+xor edi, edi
+mov ebx, 10  ; base
+lodsb
+sub al, '0'
+js .no_input
+cmp al, 9
+jle .got_char
+.no_input:
+stc ; set CF
+jmp .dec_done
+.loop:
+lodsb
+sub al, '0'
+js .dec_done
+cmp al, 9
+jg .dec_done
+.got_char:
+xchg edi,eax
+mul ebx
+add edi,eax
+jmp .loop
+clc ; clear CF
+.dec_done:
+mov eax,edi
+pop edi
+pop edx
+pop ebx
+ret
+
+; input in EAX, all regs unmodified
+print_dec:
+pushad ; save regs
+; max 4294967296 is 10 chars
+; round to nearest 32-bit boundary
+sub esp, 12
+; string in ECX, length in EDX
+lea ecx, [esp+11] ; last possible byte
+; check for 0
+test eax, eax
+jz .zero
+mov ebx, 10 ; base 10
+xor esi, esi ; counter
+.div_shit:
+xor edx, edx
+; divide
+div ebx
+dec ecx ; next char
+inc esi
+; store
+add dl, '0'
+mov byte [ecx], dl
+; check if done
+test eax, eax
+jnz .div_shit ; continue
+mov edx, esi ; counter in edx
+jmp .write
+.zero:
+mov byte [ecx], '0'
+mov edx, 1 ; length
+.write:
+mov eax, 4 ; write
+mov ebx, 1 ; stdout
+int 0x80
+add esp, 12 ; restore stack
+popad ; restore regs
+ret