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140 lines
6.0 KiB
Plaintext
140 lines
6.0 KiB
Plaintext
File System Input/Output Functions for C02 Programs
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This library contains functions for file handling. These functions
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are included here instead of in stdio.h because not all 6502 systems
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support file based input/output. Functions that are not part of the
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standard C libraries begin with the letters "fs".
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At the beginning of the program use the directives
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#include <stdio.h02>
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#include <file.h02>
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The following functions are defined:
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fsinit(); Initialize file system.
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This function should be called before calling
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before any other file functions.
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Note: Closes any open files and initializes
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the library's internal file table.
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f = fsptr(); Find an available file pointer.
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Returns 0 if no more file pointers are available.
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Note: This is called by the fopen() function, which
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does the actual file allocation and is of limited
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use in application programming.
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r = fschk(f); Check to see if f is a valid file pointer.
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Returns 0 if valid, otherwise 255.
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Note: Called by the fclose(), feof(), fgetc(),
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fgets(), fputc(), fputs(), fread(), and fwrite()
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functions.
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r = fstat(f); Get status of file table entry or last file error.
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If f is 0, returns a system dependent value
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corresponding to the last filesystem I/O error.
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If f is a potentially valid file pointer. returns a
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value representing the state of the corresponding
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entry in the file table. If the file table entry is
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unused, then a 0 is returned. Otherwise, a system
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dependent system dependent value is returned.
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If f does not point to a valid file table entry,
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then 255 is returned.
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Note: On CBM machines, fstat(0) returns the result
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of READST directly after the last error. Valid file
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pointer values are between 1 and FOMAX, inclusive
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and return a value with bits 0 through 3 containing
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the Kernal device number, and bit 7 set if an End of
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File or other error was encountered.
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f = fopen(d, &n); Open file specified from null-terminated string n
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on device d, returning a pointer to the file.
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Return 0 if the file could not be opened.
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Note: On CBM machines, d is the device number and
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f is a logical file nunber as used in a Basic Open
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statement. Up to 7 files may be opened at a time.
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r = fclose(f); Close file pointed to by f, returning 0 if
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successful or 255 if there was an error.
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Note: Returns 255 if f is not a valid file pointer.
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c = fgetc(f); Read character from file opened to by filepointer f.
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Returns character read from file.
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Note: Returns 255 if f is not a valid file pointer.
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Returns a system dependent garbage character if end
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of file has been reached or any other I/O error. Use
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feof(f) and fstat(0) to check for these conditions.
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fputc(f, c); Write character c to file opened to filepointer f.
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Use feof(f) and fstat(0) to check for errors after
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write.
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-----------------------------------------------------------------
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r = getstr(&s); Reads a maximum of 128 characters from keyboard
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until the Return/Enter key is pressed, storing the
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entered characters as null-terminated string s.
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Allows corrections using Backspace/Delete.
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Pressing the Escape/Abort key terminates entry,
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leaving the string in an undefined state.
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Returns number of characters entered, or 255
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if entry was aborted.
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Note: Calls getchr() in a loop and uses constants
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DELKEY, RTNKEY, and ESCKEY from the system library.
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r = putstr(&s): Writes up to 128 characters of null-terminated
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string s to the screen and advances the cursor to
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the beginning of the next line.
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Returns number of characters printed.
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Note: Calls outstr(&s) followed by newlin().
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Note: This library expects the following functions to be defined:
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setdst(&s); Set destination string pointer
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setsrc(&s); Set source string pointer and initialize index
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along with the zero page variable pairs
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dstlo,dsthi: Destination string pointer
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srclo,srchi: Source string pointer
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the static array
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ftbl[FOMAX]
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and the assembler constant
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FOMAX The maximum number of files that can be opened
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at one time.
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as well as the data structure
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FTBL A system dependent table of bytes containing data
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related to files opened by the fopen() function.
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See function fstat() for more information.
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