BOOL check_game_for_save(strid_t gamefile, zword release, const char serial[6],
zword checksum)
{
int i;
unsigned char header[64];
glk_stream_set_position(gamefile, 0, seekmode_Start);
if(glk_get_buffer_stream(gamefile, (char *) header, 64) != 64)
return FALSE;
if(header[HD_ZVERSION] == 0 || header[HD_ZVERSION] > 8)
return FALSE;
if(MSBdecodeZ(header + HD_RELNUM) != release)
return FALSE;
if(MSBdecodeZ(header + HD_CHECKSUM) != checksum)
return FALSE;
for(i = 0; i < 6; i++) {
if(header[HD_SERNUM + i] != serial[i])
return FALSE;
}
return TRUE;
}
BOOL quetzal_stack_restore(strid_t stream, glui32 qsize)
{
glui32 i = 0;
int num_frames = 0;
kill_stack();
init_stack(1024, 128);
while(i < qsize) {
unsigned n;
unsigned num_locals;
zword locals[16];
int num_args;
int var;
glui32 qframe[5];
i += fillstruct(stream, qstackframe, qframe, NULL);
if(qframe[qreturnPC] > total_size) {
n_show_error(E_SAVE, "function return PC past end of memory",
qframe[qreturnPC]);
return FALSE;
}
if((qframe[qflags] & b11100000) != 0) {
n_show_error(E_SAVE, "expected top bits of flag to be zero", qframe[qflags]);
return FALSE;
}
var = qframe[qvar];
if(qframe[qflags] & b00010000) /* from a call_n */
var = -1;
num_locals = qframe[qflags] & b00001111;
if(num_locals > 15) {
n_show_error(E_SAVE, "too many locals", num_locals);
return FALSE;
}
num_args = 0;
switch(qframe[qargs]) {
default:
n_show_error(E_SAVE, "invalid argument count", qframe[qargs]);
return FALSE;
case b01111111: num_args++;
case b00111111: num_args++;
case b00011111: num_args++;
case b00001111: num_args++;
case b00000111: num_args++;
case b00000011: num_args++;
case b00000001: num_args++;
case b00000000: ;
}
for(n = 0; n < num_locals; n++) {
unsigned char v[ZWORD_SIZE];
glk_get_buffer_stream(stream, (char *) v, ZWORD_SIZE);
locals[n] = MSBdecodeZ(v);
i+=ZWORD_SIZE;
}
if(zversion != 6 && num_frames == 0)
; /* dummy stack frame; don't really use it */
else
add_stack_frame(qframe[qreturnPC],
num_locals, locals,
num_args, var);
for(n = 0; n < qframe[qeval]; n++) {
unsigned char v[ZWORD_SIZE];
glk_get_buffer_stream(stream, (char *) v, ZWORD_SIZE);
stack_push(MSBdecodeZ(v));
i += ZWORD_SIZE;
}
num_frames++;
}
if(!verify_stack()) {
n_show_error(E_SAVE, "restored stack fails verification", 0);
return FALSE;
}
return TRUE;
}
