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z80a: add stuctured flow words
Allow us to rely a little less on labels. We now only need 4.
This commit is contained in:
Virgil Dupras
parent
7d184b9e70
commit
7292d486dc
@ -159,7 +159,7 @@ PC ORG @ 4 + ! ( find )
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adjust. Because the compare loop pre-decrements, instead
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of DECing HL twice, we DEC it once. )
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HL DECss,
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L3 BSET ( inner )
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BEGIN, ( inner )
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( DE is a wordref, first step, do our len correspond? )
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HL PUSHqq, ( --> lvl 1 )
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DE PUSHqq, ( --> lvl 2 )
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@ -172,15 +172,15 @@ L3 BSET ( inner )
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DE DECss, ( Skip prev field. One less because we )
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DE DECss, ( pre-decrement )
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B C LDrr, ( loop C times )
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L5 BSET ( loop )
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BEGIN, ( loop )
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( pre-decrement for easier Z matching )
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DE DECss,
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HL DECss,
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LDA(DE),
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(HL) CPr,
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JRNZ, L6 FWR ( loopend )
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DJNZ, L5 BWR ( loop )
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L4 FSET L6 FSET ( loopend )
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JRNZ, L3 FWR ( loopend )
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DJNZ, AGAIN, ( loop )
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L4 FSET L3 FSET ( loopend )
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( At this point, Z is set if we have a match. In all cases,
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we want to pop HL and DE )
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DE POPqq, ( <-- lvl 2 )
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@ -201,14 +201,14 @@ L4 FSET L6 FSET ( loopend )
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( HL is prev field's addr. Is offset zero? )
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A D LDrr,
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E ORr,
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JRZ, L6 FWR ( noprev )
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( get absolute addr from offset )
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( carry cleared from "or e" )
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DE SBCHLss,
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EXDEHL, ( result in DE )
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L6 FSET ( noprev )
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IFZ, ( noprev )
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( get absolute addr from offset )
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( carry cleared from "or e" )
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DE SBCHLss,
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EXDEHL, ( result in DE )
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THEN, ( noprev )
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HL POPqq, ( <-- lvl 1 )
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JRNZ, L3 BWR ( inner, try to match again )
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JRNZ, AGAIN, ( inner, try to match again )
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( Z set? end of dict, unset Z )
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L1 FSET ( fail )
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A XORr,
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@ -16,18 +16,16 @@
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To avoid using dict memory in compilation targets, we
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pre-declare label variables here, which means we have a
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limited number of it. For now, 6 ought to be enough. )
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limited number of it. For now, 4 ought to be enough. )
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: L1 2 Z80AMEM+ ;
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: L2 4 Z80AMEM+ ;
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: L3 6 Z80AMEM+ ;
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: L4 8 Z80AMEM+ ;
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: L5 10 Z80AMEM+ ;
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: L6 12 Z80AMEM+ ;
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: Z80A$
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( 59 == z80a's memory )
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H@ 0x59 RAM+ !
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14 ALLOT
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10 ALLOT
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;
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( Splits word into msb/lsb, lsb being on TOS )
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@ -43,42 +41,6 @@
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: A, C, ;
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: A,, SPLITB A, A, ;
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( There are 2 label types: backward and forward. For each
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type, there are two actions: set and write. Setting a label
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is declaring where it is. It has to be performed at the
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label's destination. Writing a label is writing its offset
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difference to the binary result. It has to be done right
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after a relative jump operation. Yes, labels are only for
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relative jumps.
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For backward labels, set happens before write. For forward
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labels, write happen before set. The write operation writes
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a dummy placeholder, and then the set operation writes the
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offset at that placeholder's address.
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Variable actions are expected to be called with labels in
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front of them. Example, "L2 FSET"
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About that "1 -": z80 relative jumps record "e-2", that is,
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the offset that *counts the 2 bytes of the jump itself*.
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Because we set the label *after* the jump OP1 itself, that's
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1 byte that is taken care of. We still need to adjust by
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another byte before writing the offset.
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)
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: BSET PC SWAP ! ;
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: BWR @ PC - 1 - A, ;
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( same as BSET, but we need to write a placeholder )
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: FWR BSET 0 A, ;
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: FSET
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@ DUP PC ( l l pc )
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-^ 1 - ( l off )
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( warning: l is a PC offset, not a mem addr! )
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SWAP ORG @ + ( off addr )
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C!
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;
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( "r" register constants )
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7 CONSTANT A
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0 CONSTANT B
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@ -375,3 +337,52 @@
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( Routines )
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( 29 == chkPS )
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: chkPS, 29 CALLnn, ;
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( Flow
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There are 2 label types: backward and forward. For each
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type, there are two actions: set and write. Setting a label
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is declaring where it is. It has to be performed at the
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label's destination. Writing a label is writing its offset
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difference to the binary result. It has to be done right
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after a relative jump operation. Yes, labels are only for
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relative jumps.
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For backward labels, set happens before write. For forward
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labels, write happen before set. The write operation writes
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a dummy placeholder, and then the set operation writes the
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offset at that placeholder's address.
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Variable actions are expected to be called with labels in
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front of them. Example, "L2 FSET"
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About that "1 -": z80 relative jumps record "e-2", that is,
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the offset that *counts the 2 bytes of the jump itself*.
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Because we set the label *after* the jump OP1 itself, that's
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1 byte that is taken care of. We still need to adjust by
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another byte before writing the offset.
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)
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( Place BEGIN, where you want to jump back and AGAIN after
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a relative jump operator. Just like BSET and BWR. )
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: BEGIN, PC ;
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: AGAIN, PC - 1 - A, ;
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: BSET PC SWAP ! ;
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: BWR @ AGAIN, ;
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( same as BSET, but we need to write a placeholder )
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: FJR, PC 0 A, ;
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: IFZ, JRZ, FJR, ;
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: IFNZ, JRNZ, FJR, ;
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: IFC, JRC, FJR, ;
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: IFNC, JRNC, FJR, ;
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: THEN,
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DUP PC ( l l pc )
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-^ 1 - ( l off )
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( warning: l is a PC offset, not a mem addr! )
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SWAP ORG @ + ( off addr )
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C!
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;
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: FWR BSET 0 A, ;
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: FSET @ THEN, ;
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@ -149,10 +149,10 @@ CODE NOT
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A L LDrr,
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H ORr,
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HL 0 LDddnn,
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JRNZ, L1 FWR ( skip )
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( false, make 1 )
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HL INCss,
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L1 FSET ( skip )
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IFNZ, ( skip )
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( false, make 1 )
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HL INCss,
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THEN, ( skip )
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HL PUSHqq,
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;CODE
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@ -203,17 +203,17 @@ CODE /MOD
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A B LDrr,
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B 16 LDrn,
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HL 0 LDddnn,
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L1 BSET ( loop )
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SCF,
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C RLr,
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RLA,
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HL ADCHLss,
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DE SBCHLss,
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JRNC, L2 FWR ( skip )
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DE ADDHLss,
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C DECr,
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L2 FSET ( skip )
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DJNZ, L1 BWR ( loop )
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BEGIN, ( loop )
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SCF,
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C RLr,
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RLA,
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HL ADCHLss,
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DE SBCHLss,
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IFNC, ( skip )
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DE ADDHLss,
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C DECr,
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THEN, ( skip )
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DJNZ, AGAIN, ( loop )
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B A LDrr,
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HL PUSHqq,
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BC PUSHqq,
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@ -315,16 +315,16 @@ CODE SCMP
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DE POPqq,
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HL POPqq,
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chkPS,
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L1 BSET ( loop )
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LDA(DE),
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(HL) CPr,
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JRNZ, L2 FWR ( not equal? break early to "end".
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NZ is set. )
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A ORr, ( if our char is null, stop )
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HL INCss,
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DE INCss,
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JRNZ, L1 BWR ( loop )
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L2 FSET ( end )
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BEGIN, ( loop )
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LDA(DE),
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(HL) CPr,
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JRNZ, L1 FWR ( not equal? break early to "end".
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NZ is set. )
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A ORr, ( if our char is null, stop )
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HL INCss,
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DE INCss,
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JRNZ, AGAIN, ( loop )
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L1 FSET ( end )
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( 40 == flagsToBC )
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40 CALLnn,
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BC PUSHqq,
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@ -347,13 +347,13 @@ CODE _find
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chkPS,
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( 3 == find )
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3 CALLnn,
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JRZ, L1 FWR ( found )
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( not found )
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HL PUSHqq,
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DE 0 LDddnn,
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DE PUSHqq,
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JPNEXT,
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L1 FSET ( found )
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IFZ, ( found )
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( not found )
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HL PUSHqq,
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DE 0 LDddnn,
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DE PUSHqq,
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JPNEXT,
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THEN, ( found )
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DE PUSHqq,
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DE 1 LDddnn,
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DE PUSHqq,
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