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/*
** File: support.c
**
** (C)opyright 1987-1992 InfoTaskforce.
*/
#include "infocom.h"
Void
null ()
{
/*
** The NULL function
*/
}
Void
restart ()
{
extern word save_blocks ;
extern byte_ptr base_ptr ;
new_line () ;
load_page ( 0,save_blocks,base_ptr ) ;
init_interpreter ( TRUE ) ;
}
Void
quit ()
{
extern boolean stop ;
stop = TRUE ;
}
Void
verify ()
{
extern word resident_blocks ;
extern header data_head ;
register word sum ;
register word addr_hi ;
register word addr_lo ;
word page ;
word offset ;
word save ;
if ( data_head.z_code_version <= VERSION_3 )
{
addr_lo = STD_OFFSET ( data_head.verify_length ) ;
addr_hi = STD_PAGE ( data_head.verify_length ) ;
}
else
{
addr_lo = PLUS_OFFSET ( data_head.verify_length ) ;
addr_hi = PLUS_PAGE ( data_head.verify_length ) ;
}
save = resident_blocks ;
resident_blocks = 0 ;
page = 0 ;
offset = sizeof ( header ) ;
sum = 0 ;
while (( page != addr_hi ) || ( offset != addr_lo ))
sum += get_byte ( &page,&offset ) ;
resident_blocks = save ;
if ( sum == data_head.verify_checksum )
ret_value ( TRUE ) ;
else
ret_value ( FALSE ) ;
}
Void
store ( value )
word value ;
{
extern word *stack ;
word var ;
var = next_byte () ;
if ( var == 0 )
*(--stack) = value ;
else
put_var ( var,value ) ;
}
Void
ret_value ( result )
word result ;
{
extern word pc_offset ;
word branch ;
branch = next_byte () ;
/*
** Test bit 7
*/
if (( branch & 0x80 ) != 0 )
{
/*
** Clear bit 7
*/
branch &= 0x7F ;
++result ;
}
/*
** Test bit 6
*/
if (( branch & 0x40 ) == 0 )
{
branch = ( branch << BITS_PER_BYTE ) | next_byte () ;
/*
** Test bit D. If set, make branch negative.
*/
if ( branch & 0x2000 )
branch |= 0xC000 ;
}
else
{
/*
** Clear bit 6
*/
branch &= 0xBF ;
}
if (( --result ) != 0 )
{
switch ( branch )
{
case 0 : ret_false () ;
break ;
case 1 : ret_true () ;
break ;
default : pc_offset += ( branch - 2 ) ;
fix_pc () ;
}
}
}
byte
get_byte ( page,offset )
word *page ;
word *offset ;
{
extern word resident_blocks ;
extern byte_ptr base_ptr ;
byte_ptr ptr ;
if ( *page < resident_blocks )
ptr = base_ptr + ((signed_long)*page * BLOCK_SIZE) + *offset ;
else
ptr = fetch_page ( *page ) + *offset ;
++(*offset) ;
if ( *offset == BLOCK_SIZE )
{
*offset = 0 ;
++(*page) ;
}
return ( *ptr ) ;
}
word
get_word ( page,offset )
word *page ;
word *offset ;
{
word temp ;
temp = get_byte ( page,offset ) << BITS_PER_BYTE ;
return ( temp | get_byte ( page,offset ) ) ;
}
byte
next_byte ()
{
extern word pc_offset ;
extern byte_ptr prog_block_ptr ;
register byte_ptr ptr ;
ptr = prog_block_ptr + pc_offset++ ;
if ( pc_offset == BLOCK_SIZE )
fix_pc () ;
return ( *ptr ) ;
}
word
next_word ()
{
word temp ;
temp = next_byte () << BITS_PER_BYTE ;
return ( temp | next_byte () ) ;
}
Void
error ( err_num )
word err_num ;
{
char ch[4] ;
/*
** 'err_num' must be between 00 and 99 inclusive.
** We can't use print_char or print_num because the print
** buffer may not yet have been created or initialised.
*/
display ( "\nInternal Error " ) ;
if ( err_num != ERR_MEMORY )
{
ch[0] = '#' ;
ch[1] = '0' + ( err_num / 10 ) ;
ch[2] = '0' + ( err_num % 10 ) ;
ch[3] = 0 ;
display ( ch ) ;
}
display ( "\n" ) ;
quit () ;
}
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