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181 lines
3.1 KiB
C
181 lines
3.1 KiB
C
/*
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* table.c
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*
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* Table handling opcodes
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*
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*/
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#include "frotz.h"
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/*
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* z_copy_table, copy a table or fill it with zeroes.
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*
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* zargs[0] = address of table
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* zargs[1] = destination address or 0 for fill
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* zargs[2] = size of table
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*
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* Note: Copying is safe even when source and destination overlap; but
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* if zargs[1] is negative the table _must_ be copied forwards.
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*
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*/
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void z_copy_table (void)
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{
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zword addr;
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zword size = zargs[2];
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zbyte value;
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int i;
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if (zargs[1] == 0) /* zero table */
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for (i = 0; i < size; i++)
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storeb ((zword) (zargs[0] + i), 0);
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else if ((short) size < 0 || zargs[0] > zargs[1]) /* copy forwards */
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for (i = 0; i < (((short) size < 0) ? - (short) size : size); i++) {
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addr = zargs[0] + i;
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LOW_BYTE (addr, value)
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storeb ((zword) (zargs[1] + i), value);
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}
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else /* copy backwards */
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for (i = size - 1; i >= 0; i--) {
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addr = zargs[0] + i;
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LOW_BYTE (addr, value)
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storeb ((zword) (zargs[1] + i), value);
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}
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}/* z_copy_table */
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/*
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* z_loadb, store a value from a table of bytes.
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*
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* zargs[0] = address of table
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* zargs[1] = index of table entry to store
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*
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*/
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void z_loadb (void)
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{
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zword addr = zargs[0] + zargs[1];
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zbyte value;
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LOW_BYTE (addr, value)
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store (value);
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}/* z_loadb */
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/*
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* z_loadw, store a value from a table of words.
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*
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* zargs[0] = address of table
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* zargs[1] = index of table entry to store
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*
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*/
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void z_loadw (void)
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{
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zword addr = zargs[0] + 2 * zargs[1];
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zword value;
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LOW_WORD (addr, value)
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store (value);
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}/* z_loadw */
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/*
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* z_scan_table, find and store the address of a target within a table.
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*
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* zargs[0] = target value to be searched for
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* zargs[1] = address of table
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* zargs[2] = number of table entries to check value against
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* zargs[3] = type of table (optional, defaults to 0x82)
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*
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* Note: The table is a word array if bit 7 of zargs[3] is set; otherwise
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* it's a byte array. The lower bits hold the address step.
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*
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*/
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void z_scan_table (void)
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{
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zword addr = zargs[1];
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int i;
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/* Supply default arguments */
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if (zargc < 4)
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zargs[3] = 0x82;
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/* Scan byte or word array */
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for (i = 0; i < zargs[2]; i++) {
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if (zargs[3] & 0x80) { /* scan word array */
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zword wvalue;
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LOW_WORD (addr, wvalue)
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if (wvalue == zargs[0])
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goto finished;
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} else { /* scan byte array */
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zbyte bvalue;
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LOW_BYTE (addr, bvalue)
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if (bvalue == zargs[0])
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goto finished;
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}
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addr += zargs[3] & 0x7f;
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}
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addr = 0;
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finished:
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store (addr);
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branch (addr);
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}/* z_scan_table */
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/*
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* z_storeb, write a byte into a table of bytes.
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*
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* zargs[0] = address of table
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* zargs[1] = index of table entry
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* zargs[2] = value to be written
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*
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*/
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void z_storeb (void)
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{
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storeb ((zword) (zargs[0] + zargs[1]), zargs[2]);
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}/* z_storeb */
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/*
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* z_storew, write a word into a table of words.
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*
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* zargs[0] = address of table
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* zargs[1] = index of table entry
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* zargs[2] = value to be written
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*
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*/
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void z_storew (void)
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{
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storew ((zword) (zargs[0] + 2 * zargs[1]), zargs[2]);
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}/* z_storew */
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