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180 lines
8.0 KiB
Plaintext
180 lines
8.0 KiB
Plaintext
Sta Functions
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This library contains functions to access and manipulate a stack. The
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entries on a stack are stored in contiguous bytes of memory.
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Each element of the stack can vary in size from 1 to 255 bytes. Both
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arrays and strings may be pushed onto and pulled off the stack.
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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 functions are defined:
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stkbgn(&b); Stack Begin: Sets the beginning of the stack
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to address b.
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The beginning of a stack is the first byte
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of memory in the stack space.
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Although stack space usually begins on a 256
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byte boundary, this is not required.
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Note: Sets variables stkslo and stkshi.
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stkend(&e); Stack End: Sets the end of the stack to address
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e. The end of a stack is the byte after the last
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byte of memory in the stack space.
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Although stack space usually ends on a 256
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byte boundary, this is not required.
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Note: Sets variables stkelo and steshi.
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stkrst(); Stack Reset: Set stack pointer to stack begin
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address.
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This routine is called before populating a
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stack with calls to the stkpsh function.
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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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If n is 0 or the new entry would overflow the
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end of the stack space, no entry is created and
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a value of 0 is returned. Otherwise, the number
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of bytes in the new entry is returned.
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Note: Sets dstlo and dsthi to stkslo and stkhi
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prior to the copy, updates stkslo and stkshi,
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then calls the memcpy function.
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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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If the string is empty or the bew entry would
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overflow the end of the stack space, no entry is
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created and a value of 0 is returned. Otherwise,
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the number of bytes in the new entry is returned.
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Note: Calls the strlen function, then calls the
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stkpsh function.
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r = stkpop(&m); Stack Pop: Copies the bytes from the last entry of
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the stack into array m and removes the entry from
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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 entry
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is returned.
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Note: Sets dstlo and dsthi to the address of m,
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updates stklo and stkhi to point to the beginning
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of the last entry, sets srclo and srchi to stklo
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and stkhi, then calls the memcpy function.
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r = stktop(&m); Stack Top: Copies the bytes from the last entry of
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the stack into array m and leaves the entry on 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 entry is
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returned.
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Note: Calls stkpop, then restores stklo and stkhi
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to their prior values.
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r = stkdup(); Stack Duplicate: Creates a new entry at the end of
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the stack consisting of the bytes in the last entry
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of the stack.
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If the stack is empty or the new entry would
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overflow the end of the stack space, no entry is
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created and a value of 0 is returned. Otherwise,
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the number of bytes in the new entry is returned.
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Note: Sets dstlo and dsthi to the stklo and stkhi,
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sets srclo and srchi to point to the beginning
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of the last entry, updates stklo and stkhi, then
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calls the memcpy function.
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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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If there are less than two entries in the stack
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or the new entry would overflow the end of the
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stack space, no entry is created and a value of
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0 is returned. Otherwise, the number of bytes in
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the new entry is returned.
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Note: Sets dstlo and dsthi to the stklo and stkhi,
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sets srclo and srchi to point to the beginning
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of the second to last entry, updates stklo and
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stkhi, then calls the memcpy function.
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stkswp(n); 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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If there are less than two entries in the stack
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or there is not enough room in the stack space
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to make a copy of the second to last entry, the
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entries are not swapped and a value of 0 is
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returned. Otherwise, the number of bytes in the
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new last entry is returned.
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Note: Calls stkovr, creating a copy of the second
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to last stack entry, restores stklo and stkhi to
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their original values, then calls the memcpy twice.
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*,m,l = stkptr(); Stack Pointer: Returns the address contained in
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the stack pointer as the most significant byte
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and the least significant byte.
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This is a utility function not normally used in
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application code.
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Note: Gets variables stkslo and stkshi.
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stkset(&d); Stack Set: Sets stack pointer to address d.
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This is a utility function not normally used in
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application code.
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Note: Sets variables stkslo and stkshi.
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Note: This library expects the following functions to be defined
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memcpl Copy memory (alternate entry point)
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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 and initialize index
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strlen Get string length
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along with the zero page variable pairs
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srclo, srchi Source String Pointer
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dstlo, dsthi Destination String Pointer
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stklo, stkhi stack Pointer
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the static variable
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stkslo, stkshi Stack Start Address
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stkelo, stkehi Stack End Address
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as well as the transient variables
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temp0, temp1 Temporary storage
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temp2, temp3
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