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105 lines
4.6 KiB
Plaintext
105 lines
4.6 KiB
Plaintext
Memory File I/O Functions
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This library contains functions that mimic file input/ouput operations,
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but read and write directly to RAM. It is intended to allow for the
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design of programs using these functions even on systems that do not
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include any sort of filesystem support, but do allow blocks of memory
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to be loaded from and saved to external storage. For this reason, each
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function has the same signature it's equivalent in the file library.
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At the beginning of the program use the directives
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#include <memio.h02>
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The following functions are defined:
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m = mopen(z, &a); Open memory file, using zero-page bytes z and z+1
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as a pointer and a as the starting address of the
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file. The starting address must be at least $0100.
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Returns the the z as the "file pointer", or 0 if an
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invalid address is specified.
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r = mclose(m); Close memory file pointed to by m, by writing an
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EOF and clearing the memory pointer.
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Returns 0 if successful or 255 if m contains an
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invalid address.
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Note: Calls mflush() then sets the bytes at`m and
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m+1 to 0.
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r = mflush(m); Flush memory file pointed to by m, by writing a
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NUL character at the memory pointer to 0.
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Returns 0 if successful or 255 if m contains an
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invalid address.
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Note: The NUL character (ASCII code 0) is use as the
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EOF marker because many systems initialize RAM to 0,
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it's the easiest character to test for, and it can
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never be part of a C style string.
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c = mgetc(m); Read character from memory file pointed to by m.
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Returns character read from file.
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Note: Returns 255 if m contains an invalid address.
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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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meof(f) and merror(f) to check for these conditions.
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r = mputc(m, c); Write character c to memory file opened to m.
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Returns 0 if successful or 255 if m contains an
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invalid address.
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n, c = mgets(m, &s); Reads a maximum of 128 characters from keyboard until
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a newline or EOF character is encountered, storing the
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entered characters as null-terminated string s.
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Returns number of characters entered ( 255 if m
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contains an invalid address) and the final character
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of the returned atring.
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Note: Any ASCII control character between EOF (code 0)
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and Space (code 32) is interpreted as a newline. This
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character will be included as the last character of
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the string.
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n, c = mputs(m, &s): Writes up to 128 characters of null-terminated string
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s to the memory file. Does not write a trailing C/R.
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Returns number of characters written, or 255 if m
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contains an invalid address.
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r = mputln(m, &s): Writes up to 128 characters of null-terminated string
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s followed by a C/R to the memory file.
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Returns 0 if successful or 255 if m contains an
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invalid address.
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Note: Calls mputs() followed by mputc().
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l, h = maddr(m); Returns the address contained in memory pointer m
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as two bytes in LSB, MSB format.
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This non-standard function is included for debugging
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purposes.
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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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and the assembler constant
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EOFCHR End of File character code`
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RTNCHR Carriage Return character code
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