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171 lines
7.8 KiB
Plaintext
171 lines
7.8 KiB
Plaintext
Block Memory Functions
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This library contains functions for accessing data in blocks of memory.
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A block consists of up to 65,535 contiguous bytes. This allows for the
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storage, retrieval, and manipulation of data exceeding the maximum
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array length of 255.
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These functions assume that a block is divided into equally sized segments
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of up to 255 bytes in length. Data in the block is accessed by copying
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data into and out of arrays with the same length as the segment size.
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A segment consists of a string field, which is used as a key, followed
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by a number of individual bytes. For example, the segments in a variable
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table might be 9 bytes long, consisting of a 7 byte variable name string
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(6 characters plus a terminator), the variable type (at index 7) and
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the variable length (at index 8).
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Usage: at the beginning of the program use the directives
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#include <memory.h02>
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#include <string.h02>
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#include <block.h02>
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The following application functions are defined:
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blkbgn(&b); Block Begin: Set beginning of block to address b.
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The beginning of a block is the first byte of memory
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in the block.
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Although a block usually begins on a 256 byte
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boundary, this is not required.
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Note: Sets variables blkslo and blkshi.
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blkend(&e); Block End: Set end of block to address b. The end of
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a block is the byte after the last byte of memory in
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the block.
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Although a block usually begins on a 256 byte
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boundary, this is not required.
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Note: Sets variables blkslo and blkshi.
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blkseg(n); Block Segment: Set block segment size to n.
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Required before calls any calls that manipulate
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block segments.
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Note: Sets blklen to n.
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blkset(c); Block Set: Fill entire block with character c,
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leaving block pointer at end of block.
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Used to initialize a block before use.
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blkrst(); Block Reset: Set block segment pointer to block
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begin address.
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This routine is called before populating a block with
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calls to the blkapd function.
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blknxt(); Block Next: Move block pointer forward by the segment
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length set by a prior blkseg call.
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If the block pointer is moved past the end of the
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block, a value of 0 (false) is returned. Otherwise,
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a value of 255 (true) is returned.
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blkput(n ,&m); Block Append: Copy n bytes of array m to block
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at current pointer location, and moves block pointer
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forward by the segment length set by a prior blkseg
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call.
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If the appended bytes would overflow the end of the
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block, no bytes are copied and a value of 0 (false)
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is returned. Otherwise, the bytes are copied and
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a value of 255 (true) is returned.
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Note: Sets dstlo and dsthi to the block pointer prior
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to the copy, updates blkslo and blkshi, then calls
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the memcpy function.
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blkget(n ,&m); Block Get: Copy n bytes from block at current
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pointer location to array m, and moves block pointer
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forward by the segment length set by a prior blkseg
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call.
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If the copied bytes would overflow the end of the
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block, no bytes are copied and a value of 0 (false)
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is returned. Otherwise, the bytes are copied and
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a value of 255 (true) is returned.
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Note: Sets dstlo and dsthi to the address of m,
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srclo and srchi to the block pointer prior to the
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copy, updates blkslo and blkshi, then calls the
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memcpy function.
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blkmem(n ,&m); Block Memory search: Search block for n byte long
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segment matching array m.
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If a matching segment is found, the value 255 (true)
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is returned and the destination pointer is set to the
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address of the matching segment, allowing it to be
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overwritten with a subsequent memcpy call. Otherwise,
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the value 0 (false) is returned.
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Note: Sets srclo and srchi to the address of m,
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dstlo and dsthi to the address of the matching segment,
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and temp0 to n. Does not change the block pointer.
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blkstr(n ,&s); Block String Search: Search block for n byte long
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segments beginning with string s.
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If a matching segment is found, the value 255 (true)
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is returned and the segment is copied to the array set
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by a prior memdst call. Otherwise, the value 0 (false)
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is returned.
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Note: Sets srclo and srchi to the address of the
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segment, temp0 to n, and copies dstlo and dsthi to
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temp1 and temp2. Does not change the block pointer.
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blkswp(n); Block Swap: Swaps n bytes of array m with the current
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block segment (pointed to by the block pointer. The
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block pointer is not changed.
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Requires a prior call to the memdst function specifying
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an array at least n bytes long, which is used for
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temporary storage.
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Note: Sets temp0 to n, copies blklo and blkhi to dstlo,
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and dsthi, and calls memswp.
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blksrt(&m); Block Sort: Sort segments in block by initial string,
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using array m as temporary storage.
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Segments are sorted in alphabetical order, with segment
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length set by a prior blkseg call, and sorting stops at
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the first segment that begins with an empty string (the
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first byte is 0), leaving the block pointer at that
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segment.
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Note: Uses the selection sort algorithm. Sets temp1
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and temp2 to the address of array m.
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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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memcmp Compare memory
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memcpy Copy memory
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memsrc Set memory source and count
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strcml Compare string (alternate entry point)
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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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blklo, blkhi Block Pointer
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the static variable
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blkslo, blkshi Block Start Address
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blkelo, blkehi Block End Address
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blklen Block Segment Length
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as well as the transient variables
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temp0, temp1, temp2 Temporary storage
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