File IO
There are only some many things that you can do with files. These file operations are
common to all languages and operating systems.
The information on how to use these is in MASM32 High Level Reference, File IO Macros.
File IO Macros
Load and Save Complete File
| InputFile | Read entire file into a memory buffer |
| OutputFile | Write a memory buffer to disk |
Low Level File Operations
| fcreate | Create a new file and return its handle |
| fdelete | Delete a disk file |
| fopen | Open an existing file and return its handle |
| fclose | Close an open file handle |
| fread | Read data from an open file |
| fwrite | Write data to an open file |
| fprint | Write line of text to an open file |
| fprintc | Write text to open file with C style formatting |
| fseek | Set the current position in the open file |
| fseteof | Set the end of the open file to the current location |
| fsize | Return the size in bytes of the open file |
A Sample Look At The Documentation
fcreate
mov hFile, fcreate(filename)
Description
Create a new file with read / write access.
Parameters
1. filename A zero terminated string. This can be a quoted text.
Return Value
The return value is the handle of the new file.
Comments
The new file has read and write access. If there is an error, you should test the return value with GetLastError().
Example
mov hFile, fcreate("mynewfile.ext")
Something Is Missing
The return value is returned in EAX, so hFile has to be declared as a DWORD.
Another Sample Look At The Documentation
fprintc
fprintc hFile,"Hi Guys\n"
Description
Write zero terminated text with C style formatting to an open file.
Parameters
1. hFile The handle of the open file
2. lpText The address of a zero terminated string. This may also be quoted text that contains C style escape
sequences as provided for in the cfm$ macro.
Return Value
This macro does not return a value.
Comments
This macro allows the programmer to write text to an open file using the text formatting capacity of the cfm$ macro
which allows C style formatting of string data. It is useful where you need to sequentially append text to a file
without necessarily placing it on a new line.
cfm$ Macro
This is from the MASM32 High Level Reference, Normal String Macros.
cfm$
Description
Format a quoted string using C style escape sequences.
Parameters
A quoted string that can have escape sequences contained within it.
Return Value
The return value is the address of the formated string data as an offset in the .DATA section.
Comments
This macro is not designed to conform to the C "printf" string formatting specification, it is designed to give
this form of formatting convenience to MASM programmers who may have a C background. It can be used either
directly in a procedure call in normal code or be used in a dedicated macro that requires this style of formatting.
The direct formatting escapes are as follows, the numbers enclosed in brackets are the ASCII characters inserted
into the quoted text.
\n = newline (13,10)
\t = tab (9)
\\ = "\" backslash (92)
\q = quote (34)
The following escapes are MASM specific to bypass the restrictions that MASM places on certain characters being
contained within a quoted string.
\l = "<" left angle bracket. (60)
\r = ">" right angle bracket. (62)
\x = "!" exclaimation mark. (33)
\a = "(" left bracket. (40)
\b = ")" right bracket. (41)
Example
print cfm$("\tThis is a test\n\tof the \qfmt$\q macro\n")
Result
This is a test
of the "fmt$" macro
Sample Program
comment * =========================================
Information on StrToFloat and
FloatToStr are in the MASM32 Library
Reference, Floating Point Conversions
======================================= *
; ллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллл
include \masm32\include\masm32rt.inc
; ллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллл
comment * -----------------------------------------------------
Build this template with
"CONSOLE ASSEMBLE AND LINK"
----------------------------------------------------- *
.code
start:
; ллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллл
call main
inkey
exit
; ллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллл
main proc
LOCAL hFile :DWORD ; file handle
LOCAL bwrt :DWORD ; variable for bytes written
LOCAL txt :DWORD ; text handle
cls
sas txt,"Gary says 'Hi!'" ; assign string to local variable
mov hFile, fcreate("testfile.txt") ; create the file
mov bwrt, fwrite(hFile,txt,len(txt)) ; write data to it
; How much got written out?
mov eax, [bwrt]
print str$(eax)
print " bytes were written to the file"
print chr$(10,13)
fclose hFile ; It is good programming style to close a file as soon as possible!
ret
main endp
; ллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллллл
end start
Results On The Screen
15 bytes were written to the file
Press any key to continue ...
Results In The File
Gary says 'Hi!'