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collapseos/blk/300
Virgil Dupras 40f92b9bab z80: optimize chkPS
Inline it in next and make chkPS, call a newly reserved label for
it directly, removing a layer of indirection. This frees a spot in
the stable ABI.
2020-06-14 09:48:10 -04:00

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PC ORG @ 0x1b + ! ( next )
( This routine is jumped to at the end of every word. In it,
we jump to current IP, but we also take care of increasing
it by 2 before jumping. )
( Before we continue: are stacks within bounds? )
( PS ) HL PS_ADDR LDddnn,
SP SUBHLss,
JRC, L2 BWR ( abortUnderflow-B298 )
( RS ) IX PUSHqq, HL POPqq,
DE RS_ADDR LDddnn,
DE SUBHLss,
JRC, L2 BWR ( IX < RS_ADDR? abortUnderflow-B298 )
E 0 IY+ LDrIXY,
D 1 IY+ LDrIXY,
IY INCss, IY INCss,
( continue to execute )