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