94 lines
1.6 KiB
ArmAsm
94 lines
1.6 KiB
ArmAsm
|
|
//
|
|
// JiffyDOS protocol support for IEC
|
|
//
|
|
|
|
// XXX finish this
|
|
|
|
|
|
|
|
#if CONFIG_IEC_JIFFYDOS
|
|
|
|
|
|
iec_tx_byte_jiffydos:
|
|
|
|
// JiffyDOS timing regime is very strict - before transmitting anything
|
|
// we need to disable sprites and (if screen is not disabled) wait for
|
|
// appropriate moment, so that no badline interruption can happen
|
|
|
|
jsr jiffydos_hide_sprites
|
|
jsr jiffydos_wait_line
|
|
|
|
__jd_check1:
|
|
|
|
// XXX send byte
|
|
|
|
// Re-enable sprites
|
|
jsr jiffydos_restore_sprites
|
|
|
|
rts
|
|
|
|
|
|
iec_rx_byte_jiffydos:
|
|
|
|
// JiffyDOS timing regime is very strict - before transmitting anything
|
|
// we need to disable sprites and (if screen is not disabled) wait for
|
|
// appropriate moment, so that no badline interruption can happen
|
|
|
|
jsr jiffydos_hide_sprites
|
|
jsr jiffydos_wait_line
|
|
|
|
// XXX retrieve byte
|
|
|
|
// Re-enable sprites
|
|
jsr jiffydos_restore_sprites
|
|
|
|
rts
|
|
|
|
|
|
jiffydos_wait_line:
|
|
|
|
// XXX if screen not disabled, wait for badline to pass
|
|
|
|
rts
|
|
|
|
|
|
__jd_check2:
|
|
|
|
|
|
jiffydos_hide_sprites:
|
|
|
|
// XXX implement
|
|
|
|
rts
|
|
|
|
|
|
jiffydos_restore_sprites:
|
|
|
|
// XXX implement
|
|
|
|
rts
|
|
|
|
|
|
.function SAME_PAGE_CHECK(label_1, label_2)
|
|
{
|
|
#if PASS_SIZETEST
|
|
.return (label_1 - label_1 % 256) == (label_2 - label_2 % 256)
|
|
#else
|
|
.return true
|
|
#endif
|
|
}
|
|
|
|
.if (!SAME_PAGE_CHECK(__jd_check1, __jd_check2))
|
|
{
|
|
// To meet the strict JiffyDOS timing, we need to make sure
|
|
// it does not span across multiple pages, as this would add
|
|
// 1 cycle to some jump instructions - maybe this wont cause
|
|
// problems, but better safe than sorry.
|
|
|
|
.error "JiffyDOS code can't span across multiple pages"
|
|
}
|
|
|
|
|
|
#endif // CONFIG_IEC_JIFFYDOS
|