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174 lines
7.3 KiB
Plaintext
174 lines
7.3 KiB
Plaintext
Sta Functions
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This module contains functions to access and manipulate a stack
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of multi-byte entries stored in a contiguous section of memory.
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Each entry of the stack consists of 1 to 255 bytes of data
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followed by a single byte containing the number of data bytes,
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allowing entries to be of different sizes. Entries may be
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arrays, strings, or structs.
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Usage: at the beginning of the program use the directives
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#include <stddef.h02>
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#include <memory.h02>
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#include <string.h02>
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#include <stack.h02>
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The following application variables are defined:
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int stkbgn Stack Begin: Address of the start of the stack.
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int stkend Stack End: Address of the end of the stack.
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zeropage int stkptr Stack Pointer: Current position in the stack.
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The variables stkbgn and stkend must be set
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before calling any functions. A program can
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use multiple stacks by saving and restoring
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stkbgn, stkend, and stkptr.
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The following application functions are defined:
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stkrst(); Stack Reset: Set stack pointer to stack begin
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address.
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The first time s stack is used, this routine
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must be called after setting the variables
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stkbgn and stkend and before calling any other
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stack functions.
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This routine can also be called to deallocate
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all entries, effectively clearing the stack.
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Note: Sets stkptr to stkbgn.
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r,i = stksiz(); Stack Size: Calculates and returns the current size
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of the stack along with a flag indicating whether
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the stack is populated or empty.
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Returns a char, which will be 255 (True) if the
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stack contains at least one entry, or 0 (False) if
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the stack is empty, and int which is the size of
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the stack.
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Note: Subtracts stkbgn from stkptr.
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r = stkpsh(n,m); Stack Push: Creates a new entry at the end of
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the stack consisting of n bytes of array m.
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Returns zero if n is 0 or an overflow would
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occur. Otherwise, returns the the size of the
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new entry.
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Note: Sets srcptr to &m, dstptr to stkptr,
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updates stkptr, then calls memcpy().
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r = stkstr(s); Stack String: Creates a new entry at the end of
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the stack consisting the characters in string
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s, including the terminating ASCII null. This
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ensures that when the entry is popped off the
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stack, the destination string will be properly
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terminated.
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Returns zero if s is empty or an overflow would
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occur. Otherwise, returns the the size of the
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new entry.
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Note: Calls strlen(), then calls stkpsh().
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r = stkdup(); Stack Duplicate: Creates a new entry at the end
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of the stack consisting of the bytes in the last
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entry of the stack.
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Returns zero if the stack is empty or an overflow
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would occur. Otherwise, returns the the size of
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the new entry.
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Note: Sets dstptr to stkptr, sets srcptr to the
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beginning of the last entry, updates stkptr,
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then calls memcpy().
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r = stkovr(); Stack Over: Creates a new entry at the end of
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the stack consisting of the bytes in the second
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to last entry of the stack.
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Returns zero if the stack has less than two
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entries or an overflow would occur. Otherwise,
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returns the the size of the new entry.
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Note: Sets dstptr to the stkptr and srcptr to
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the beginning of the second to last entry,
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updates stkptr then calls the memcpy().
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r = stkswp(); Stack Swap: Moves the last entry in the stack to
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the second to last position and the second to
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last entry to the last position.
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Returns zero if the stack has less than two
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entries or an overflow would occur. Otherwise,
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returns the the size of the new last entry.
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Note: Saves stkptr, calls stkovr(), restores
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stkptr, then calls memcpy() twice.
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r = stktop(m); Stack Top: Copies the bytes from the last entry
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of the stack into array m and leaves the entry
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on the stack.
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Returns zero if the stack is empty. Otherwise,
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returns the the size of the new entry.
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Note: Saves stkptr, calls stkpop(), then restores
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stkptr.
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r = stkpop(m); Stack Pop: Copies the bytes from the last entry
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of the stack into array m and deallocates the
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entry from the stack.
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If the stack is empty, the value 0 is returned.
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Otherwise, the number of bytes in the popped
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entry is returned.
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Note: Sets dstptr to &m, sets stkptr to the
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beginning of the last entry, sets srcptr to
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stkptr, then calls the memcpy().
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r = stkdrp(); Stack Drop: Deallocates the last entry from the
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stack.
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If the stack is empty, the value 0 is returned.
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Otherwise, the number of bytes in the dropped
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entry is returned.
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Note: Sets dstptr to &m, sets stkptr to the
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beginning of the last entry, sets srcptr to
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stkptr, then calls the memcpy().
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The following utility functions are not normally used in applications:
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Note: This module expects the following functions to be defined
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memcpy Copy memory
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ressrc Restore source pointer
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resrxy Restore X and Y registers
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savrxy Save X and Y registers
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setdst Set destination pointer
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setsrc Set source pointer
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strlen Get string Length
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along with the zero page integer variables
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srcptr Source String Pointer
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dstptr Destination String Pointer
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stkptr stack Pointer
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the static integer variables
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stkbgn Stack Start Address
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stkend Stack End Address
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and the transient variables
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temp0, temp1, temp2 Temporary storage
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