ttl statement parser
 pag


*
* parse a compound statement
*

cmpstm ldd nxtaut get auto count
 ldx hdrlab save header label
 pshs d,x
 ldx nxtsym save block info
 ldy nxtsu
 ldd nxtdim
 pshs d,x,y
 inc blklev bump block level
 lbsr getok get token
 cmpa #2 is it "{"?
 beq 2f error?
 ldb #26 set error
 jsr rpterr
 bra 21f
2 clr token
21 lda blklev check for function block
 cmpa #2
 beq 22f
 jsr spctst check for declarations
 bne 22f
 ldd #0 set 0 header label
 bra 25f
22 jsr nxtlab get a label
25 std hdrlab save as new header label
 jsr ostblk output start block code
3 lbsr dcllst look for declarations
* beq cmperr
 lda blklev check if starting function block
 cmpa #2
 bne 31f
 ldd nxtaut get next auto
 bra 32f
31 ldd nxtaut check for new auto variables
 cmpd 6,s check against old count
 beq 35f
32 subd #2 make room for function space ********
 std nxtaut
35 bsr stmlst do statement list
* beq cmperr
 lbsr getok get token
 cmpa #3 is it "}"?
 beq 4f
 ldb #27
 jsr rpterr
 bra cmperr
4 clr token
 puls d,x,y
 std nxtdim
 lbsr clrlev clear out block level
 ldx hdrlab get header label
 ldd 0,s get old auto count
 subd nxtaut get difference
 jsr oenblk output end block code
 puls d,x
 std nxtaut reset old values
 stx hdrlab
 andcc #$fb set true
 rts
cmperr puls d,x,y get block info
 std nxtdim
 lbsr clrlev clear out level
 puls d,x reset values
 std nxtaut
 stx hdrlab
 clra set false
 rts return

*
* process a statement list
*

stmlst lbsr getok get token
 cmpa #3 is it "}"
 beq 2f
 cmpa #EOF end of file?
 beq 4f
1 bsr stmnt do statement
 bra stmlst
2 andcc #$fb set true
4 rts return

*
* parse an expected statement
*

stmnt lbsr getok get next token
 cmpa #19 keyword?
 bne 3f
 lda toktyp get type
 cmpa #25 IF?
 bne 1f
 lbra if
1 cmpa #30 SWITCH?
 bne 12f
 lbra switch
12 cmpa #23 BREAK?
 bne 14f
 lbra xbreak
14 cmpa #24 CONTINUE?
 bne 16f
 lbra contin
16 cmpa #40 CASE?
 bne 18f
 lbra case
18 cmpa #41 DEFAULT?
 bne 2f
 lbra defalt
2 cmpa #29 WHILE?
 bne 22f
 lbra while
22 cmpa #28 DO?
 bne 23f
 lbra do
23 cmpa #21 RETURN?
 bne 24f
 lbra return
24 cmpa #27 FOR?
 bne 25f
 lbra for
25 cmpa #20 GOTO?
 lbeq goto
 ldb #28 set error
 jmp rpteat
3 cmpa #1 ";"?
 bne 35f
 clr token
 andcc #$fb set true
 rts
35 cmpa #20 is it label?
 bne 4f
 lbsr getchr check next character
 cmpa #': is it label mark?
 bne 5f
 clr char eat the colon
 lbra dolab
4 cmpa #2 "{"?
 bne 5f
 lbra cmpstm do compound statement
5 lbsr exp
 lbeq eatsc
 lbsr getok
 cmpa #1 ";"?
 beq 55f error?
 ldb #29
 jmp rpteat
55 clr token
 andcc #$fb set true
 rts
6 clra set error
9 rts

*
* if statement (else)
*

if clr token eat token
 ldd #0
 pshs d
 pshs d save space for labels
 lbsr nxtlab get next label
 std 2,s save it
 lbsr pexp process paren exp
* beq iferr
 ldu 2,s get exit label
 clrb set false branch
 jsr ocbr
 lbsr stmnt process statement
* beq iferr
 lbsr getok get token
 cmpa #19 keyword?
 bne 4f
 lda toktyp check type
 cmpa #26 ELSE?
 bne 4f
 clr token eat token
 lbsr nxtlab get label
 std 0,s save it
 jsr obrnch output branch
 ldd 2,s output 1st label
 jsr olabel output label
 lbsr stmnt do statement
* beq iferr
 ldd 0,s get label
 bra 5f
4 ldd 2,s get label
5 jsr olabel
 leas 4,s fix stack
 andcc #$fb set true
 rts return
iferr leas 4,s fix stack
 clra set false
 rts

*
* process while statement
*

while clr token eat token
 ldd brklab save current break
 pshs d
 ldd conlab save current contin
 pshs d
 lbsr nxtlab get a label
 std conlab new contin label
 pshs d save it
 jsr olabel output label
 lbsr nxtlab get another label
 std brklab new break label
 pshs d save it
 lbsr pexp paren expression
* beq wlerr
 ldu 0,s get exit label
 clrb set false
 jsr ocbr output cond branch
 lbsr stmnt do statement
* beq wlerr
 ldd 2,s get label
 jsr obrnch output branch
 puls d get label
 jsr olabel output label
while4 leas 2,s fix stack
 puls d reset continue
 std conlab
 puls d reset break
 std brklab
 andcc #$fb set true
 rts return
wlerr leas 4,s fix stack
 puls d reset contin
 std conlab
 puls d reset break
 std brklab
 clra set false
 rts return

*
* the do statement
*

do clr token
 ldd brklab save break
 pshs d
 ldd conlab save contin
 pshs d
 lbsr nxtlab get next label
 pshs d save it
 jsr olabel output label
 lbsr nxtlab get new contin label
 pshs d
 std conlab
 lbsr nxtlab get new breal label
 pshs d
 std brklab
 lbsr stmnt process statement
* beq doerr
 lbsr getok get token
 cmpa #19 key word?
 bne 3f error?
 lda toktyp get token type
 cmpa #29 is it WHILE?
 beq 4f error?
3 ldb #30
 jmp rpteat
4 clr token
 ldd 2,s get contin label
 jsr olabel output label
 lbsr pexp process paren expression
* beq doerr
 ldu 4,s get exit label
 ldb #1 set true
 jsr ocbr output cond branch
 lbsr getok get token
 cmpa #1 is it ";"?
 beq 6f error?
 ldb #31
 jsr rptfnd
6 clr token
 puls d get break label
 jsr olabel output label
 leas 4,s fix stack
 puls d reset contin label
 std conlab
 puls d reset break label
 std brklab
 andcc #$fb
 rts
doerr leas 6,s fix stack
 puls d reset contin
 std conlab
 puls d reset break
 std brklab
 clra set false
 rts return

*
* return statement
*

return clr token
 lbsr getok get next token
 cmpa #1 is it ";"?
 beq 2f
 lbsr exp process expression
* beq reterr
 lbsr getok get next token
 cmpa #1 is it ';'?
 beq 2f error?
 ldb #31
 jsr rptfnd
2 clr token
 ldd retlab get label
 jsr obrnch output branch
 andcc #$fb set true
 rts
reterr clra
 rts return