format PE console 4.0
entry start

;Help needed below where marked

include 'win32ax.inc'

section '.data' data readable writeable
polynomial dd 0x04C11DB7
;polynomial dd 0xEDB88320
remainder dd 0

fileNotFound db "Error: File Not Found.",10,0
NEA db "Error: No arguements specified",10,0
printResult db "CRC32 of file: 0x%s",10,0
title db "CRC32 program in Assembly",0

testcount dd ?

inputFile dd ?
numArgs dd ?
numBytes dd ?
bytesRead dd ?
hSrcFile dd ?
lpBuffer db ?
htosSTR dd ?
reflection dd ?

memPTR dd ?

filePathArg dd ?

section '.text' code readable executable
start:
;========Set Console Title========
invoke SetConsoleTitleA,title
;========Get Command Line PTR=====
invoke GetCommandLineW
;========Parse To Args============
invoke CommandLineToArgvW,eax,numArgs
cmp [numArgs],2
jl not_enough_args
;========Load Second Arg==========
xor ebx,ebx
mov ebx,[eax+4] ;ptr to second arg
mov [inputFile],ebx
;========Does File Exist?=========
invoke GetFileAttributes,[inputFile]
cmp eax,-1
je file_not_found
;========Open File================
invoke CreateFile,[inputFile],GENERIC_READ,FILE_SHARE_READ,0,\
                       OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,0
cmp eax,3
jnge exit
mov [hSrcFile],eax
;========Get File Size============
invoke GetFileSize,[hSrcFile],0
mov [numBytes],eax
;========Clear Registers==========
xor ebx,ebx ;int byte = 0
xor edx,edx ;remainder = 0
;========Allocate Memory For File=
invoke GlobalAlloc,0,[numBytes]
mov [memPTR],eax
;=========Read Entire File========
invoke ReadFile,[hSrcFile],[memPTR],[numBytes],bytesRead,0
;for(int byte = 0; byte < nBytes; ++byte)
;=========CRC32 Algorithm=========
xor ecx,ecx ;temporary storage for byte

mov eax,[memPTR]
mov [remainder],0xFFFFFFFF
firstfor:
;inc ebx
mov cl,byte [eax+ebx]
shl ecx,24

xor [remainder],ecx ; remainder ^= (message[byte]) << (width-8)

push ecx
;for(uint8_t bit = 8; bit > 0; --bit)
mov ecx,8
bitbybitfor:

;if(remainder & TOPBIT)
mov edx,[remainder]

;HELP NEEDED HERE V HELP NEEDED HERE V HELP NEEDED HERE V HELP NEEDED HERE V HELP NEEDED HERE V
test edx,edx          ;Logical and without modifying registers
jns not1          ;Checking for odd/even number, equivalent to if (remainder & 80000000h) == 1
inc [testcount]       ;Put for debugging purposes, this count
                      ;Changes every time the program is run, why?
;HELP NEEDED HERE ^ HELP NEEDED HERE ^ HELP NEEDED HERE ^ HELP NEEDED HERE ^ HELP NEEDED HERE ^

mov edx,[remainder]
shl edx,1
xor edx,[polynomial]
mov [remainder],eax
jmp endfor

;else
not1:
shl [remainder],1
endfor:

dec ecx
cmp ecx,0
jnz bitbybitfor

inc ebx
cmp ebx,[numBytes]
jnz firstfor
;=========Reflection==============
xor edx,edx
mov eax,31
mov ecx,[remainder]
rfor:

test ecx,01h

jnz past
sub eax,edx
shl eax,1
;mov [reflection],eax
past:
shr ecx,1

inc edx
cmp edx,32
jnz rfor
mov [remainder],eax
;=========Final XOR===============
xor [remainder],0xFFFFFFFF
;=========Move Last Calculation===
;mov [remainder],edx
;=========Hex to String===========
invoke htos,remainder,htosSTR
;=========Flip String=============
invoke flipDW,htosSTR
;=========Print String============
invoke printf,printResult,htosSTR
;=========Stall Exitation=========
invoke getchar
;=========Exit====================
exit:
invoke ExitProcess,0
;=========File not found==========
file_not_found:
invoke printf,fileNotFound
invoke getchar
jmp exit
;=========Not Enough Args=========
not_enough_args:
invoke printf,NEA
invoke getchar
jmp exit
;=========Imports=================
section '.idata' import data readable writeable
library kernel,'KERNEL32.DLL',\
        user,'USER32.DLL',\
        shell,'SHELL32.DLL',\
        msvcrt,'MSVCRT.DLL',\
        stringfuncs,'STRINGFUNCS.DLL'
import kernel,\
       SetConsoleTitleA,'SetConsoleTitleA',\
       GetCommandLineW,'GetCommandLineW',\
       CreateFile,'CreateFileW',\
       GlobalAlloc,'GlobalAlloc',\
       ReadFile,'ReadFile',\
       GetFileAttributes,'GetFileAttributesW',\
       GetFileSize,'GetFileSize',\
       SetFilePointer,'SetFilePointer',\
       ExitProcess,'ExitProcess'
import msvcrt,\
        printf,'printf',\
        getchar,'_fgetchar'
import user,\
       MessageBox,'MessageBoxW'
import shell,\
       CommandLineToArgvW,'CommandLineToArgvW'
import stringfuncs,\
       htos,'htos',\
       flipDW,'flipDW'