This Book's Link Library (Cont.)

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CloseFile
It closes a file that was previously opened. The file is identified by a 32-bit integer handle, which is passed in EAX.

CreateOutputFile
It creates a disk file and opens it in output mode. Pass the offset of a file name in EDX. When the procedure returns,

• if the file was created successfully, EAX contains a valid file handle;
• otherwise, EAX equals INVALID_HANDLE_VALUE (a predefined constant).

OpenInputFile
It opens an existing file for input. Pass it the offset of a filename in EDX. When it returns,

• if the file was opened successfully, EAX contains a valid file handle;
• otherwise, EAX equals INVALID_HANDLE_VALUE.

ReadFromFile
It reads an input file into a buffer. Pass it an open file handle in EAX, the offset of a buffer in EDX, and the maximum number of bytes to read in ECX. When the procedure returns,

• if CF = 0, EAX contains a count of the number of bytes read from the file;
• if CF = 1, EAX contains the system error code explaining what went wrong.

WriteToFile
It writes the contents of a buffer to an output file. Pass it a valid file handle in EAX, the offset of the buffer in EDX, and the number of bytes to write in ECX. When the procedure returns, EAX contains a count of the number of bytes written.