diff options
| -rw-r--r-- | read.s | 133 |
1 files changed, 85 insertions, 48 deletions
@@ -1,64 +1,101 @@ read: -MOV #7000, R5 ; move read buffer address into R5 -; populate read buffer with console input until enter key is pressed -; filter out bad characters here. -; increment R5 along the way. -; and start with null byte. -; what we are left with is just (, ), A-Z, and space -JSR PC, #parse_sexp -JMP #eval +002000 012705 MOV #7000, R5 ; move read buffer address into R5 +002002 007000 +002004 105025 CLRB (R5)+ ; move null byte into buffer +loop: +002006 032737 BIT #000200, @#177560 +002010 000200 +002012 177560 +002014 001774 BEQ loop ; loop until char ready +002016 113701 MOVB @#177562, R1 +002020 120127 CMPB R1, "\n" ; done if enter was pressed +002022 000012 +002024 001422 BEQ done +002026 120127 CMPB R1, " " ; good if space +002030 000040 +002032 001414 BEQ good +002034 120127 CMPB R1, "(" ; good if left paren +002036 000050 +002040 001411 BEQ good +002042 120127 CMPB R1, ")" ; good if right paren +002044 000051 +002046 001406 BEQ good +002050 120127 CMPB R1, "A" ; bad if lower than A +002052 000101 +002054 103405 BLO bad +002056 120127 CMPB R1, "Z" ; bad if higher than Z +002060 000132 +002062 101002 BHI bad +good: +002064 110125 MOVB R1, (R5)+ ; move good char into buffer +002066 000747 BR loop ; keep getting chars +bad: +002070 000777 BR -2 ; infinite loop +done: +002072 000137 JMP #parse_sexp +002074 002100 ; R4 = sexps - parse_sexp: -JSR PC, #get_next ; get a character -CMPB R0, ")" -BNE if_atom ; if atom get the atom +002100 004737 JSR PC, #get_next ; get a character +002102 002300 +002104 120027 CMPB R0, ")" +002106 000051 +002110 001020 BNE if_atom ; if atom get the atom ; otherwise (if list) ; get the list if_list: -MOV "NIL", R4 ; sexps <- empty list +002112 012704 MOV "NIL", R4 ; sexps <- empty list +002114 005000 loop: -JSR PC, #get_next -CMPB R0, "(" -BEQ done ; if "(" return the accumulated list +002116 004737 JSR PC, #get_next +002120 002300 +002122 120027 CMPB R0, "(" +002124 000050 +002126 001407 BEQ done ; if "(" return the accumulated list ; if anything else: -MOV R4, -(SP) ; push sexps -JSR PC, #parse_sexp ; arg1 <- parse sexp -MOV (SP)+, R1 ; arg2 <- pop accum -JSR PC, #cons ; cons result onto accum -MOV R0, R4 ; sexps <- result -BR -??? ; continue recognizing list +002130 010446 MOV R4, -(SP) ; push sexps +002132 004737 JSR PC, #parse_sexp ; arg1 <- parse sexp +002134 012601 MOV (SP)+, R1 ; arg2 <- pop accum +002136 004737 JSR PC, #cons ; cons result onto accum +002140 004400 +002142 010004 MOV R0, R4 ; sexps <- result +002144 000764 BR loop ; continue recognizing list done: -MOV R4, R0 ; result <- sexps -RTS PC +002146 010400 MOV R4, R0 ; result <- sexps +002150 000207 RTS PC if_atom: -MOVB "\0", -(SP) ; push null byte to stack +002152 105046 CLRB -(SP) ; push null byte to stack loop: -MOVB R0, -(SP) ; push character to stack ; -MOVB -(R5), R0 ; get another character -CMPB R0, "A" ; -BLO done ; done if lower than A -CMPB R0, "Z" ; -BHI done ; done if higher than Z -BR -??? ; continue getting characters +002154 110046 MOVB R0, -(SP) ; push character to stack +002156 114500 MOVB -(R5), R0 ; get another character +002160 120027 CMPB R0, "A" ; +002162 000101 +002164 103404 BLO done ; done if lower than A +002166 120027 CMPB R0, "Z" ; +002170 000132 +002172 101001 BHI done ; done if higher than Z +002174 000767 BR loop ; continue getting characters done: -MOVB R0, (R5)+ ; put the non-letter back -MOV @#10000, R2 ; get free pointer -MOV R2, R0 ; result <- address of new atom -MOV 3(R2), (R2)+ ; allocate atom tag and increment free pointer -MOVB (SP)+, (R2)+ ; pop a char off the stack and into the heap ; increment the free pointer (by 1) -BNE -4 ; if it wasn't null keep going -TST (R2)+ ; align free pointer -MOV R2, @#10000 ; store new free pointer -RTS PC - +002176 110026 MOVB R0, (R5)+ ; put the non-letter back +002200 013702 MOV @#10000, R2 ; get free pointer +002202 010200 MOV R2, R0 ; result <- address of new atom +002204 016222 MOV 3(R2), (R2)+ ; allocate atom tag and increment free pointer +002206 000003 +loop: +002210 112622 MOVB (SP)+, (R2)+ ; pop a char off the stack and into the heap + ; increment the free pointer (by 1) +002212 001376 BNE loop ; if it wasn't null keep going +002214 005722 TST (R2)+ ; align free pointer +002216 010237 MOV R2, @#10000 ; store new free pointer +002230 000207 RTS PC get_next: loop: -MOVB -(R5), R0 -BEQ bad ; if null byte, no more input, very bad -CMPB R0, " " ; check if space -BEQ loop ; skip space -RTS PC ; return the lexically-valid character +002300 114500 MOVB -(R5), R0 +002302 001404 BEQ bad ; if null byte, no more input, very bad +002304 120027 CMPB R0, " " ; check if space +002306 000040 +002310 001773 BEQ loop ; skip space +002312 000207 RTS PC ; return the lexically-valid character bad: -BR -2 ; infinite loop +002314 000777 BR -2 ; infinite loop |