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Only read or write if a disk is in the drive

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This commit is contained in:
Peter Evans 2018-02-05 12:42:19 -06:00
parent a13be6c413
commit 4ce79c785c
1 changed files with 11 additions and 0 deletions
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11
src/apple2.dd.c
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@ -243,6 +243,12 @@ apple2_dd_position(apple2dd *drive)
vm_8bit vm_8bit
apple2_dd_read(apple2dd *drive) apple2_dd_read(apple2dd *drive)
{ {
// If we have no disk in the drive, we will always return a zero
// byte
if (drive->data == NULL) {
return 0;
}
vm_8bit byte = vm_segment_get(drive->data, apple2_dd_position(drive)); vm_8bit byte = vm_segment_get(drive->data, apple2_dd_position(drive));
apple2_dd_shift(drive, 1); apple2_dd_shift(drive, 1);
@ -359,6 +365,11 @@ apple2_dd_turn_on(apple2dd *drive, bool online)
void void
apple2_dd_write(apple2dd *drive) apple2_dd_write(apple2dd *drive)
{ {
// If there's no disk in the drive, then we can't write anything
if (drive->data == NULL) {
return;
}
vm_segment_set(drive->data, apple2_dd_position(drive), drive->latch); vm_segment_set(drive->data, apple2_dd_position(drive), drive->latch);
apple2_dd_shift(drive, 1); apple2_dd_shift(drive, 1);
} }