feat(buzbee): Implemented CALL, PEEK, POKE IFs

src/buzbee.s

@@ -29,7 +29,7 @@ BBVAR tagbbvar
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;
-;; BUZBEE Machine Language Monitor for CHIBI PC-09
+;; BUZBEE Main Loop
 ;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
@@ -43,7 +43,7 @@ BUZBEE
   cmpy #$0000 ; No data?
   beq BUZBEE  ;  Try again...
   ; TODO: Parse the input buffer into tokens
-  ; TODO: Execute the token buffer
+  lbsr RUNIF
   bra BUZBEE
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -125,7 +125,43 @@ FULLBUF@
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;
-;; BUZBEE Command Hashing Routines
+;; Hex Conversion and Printing Routines
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+; Prints a byte in A
+; @param a: byte to print
+PBYTE
+  pshs b
+  tfr a,b      ; Transfer lower nybble into B
+  andd #$F00F  ; Mask and adjsut
+  asra
+  asra
+  asra
+  asra
+  bsr NYB2HEX ; Print A
+  jsr POUTCHAR
+  tfr b,a      ; Print B next
+  bsr NYB2HEX ; Print B
+  jsr POUTCHAR
+  puls b
+  rts
+
+; Converts a nybble into a valid hex digit
+; @param a: nybble to convert to a char
+; @return a: resulting char
+NYB2HEX
+  anda #$0F
+  ora #'0     ; Add "0"
+  cmpa #$3A   ; ":" "9"+1
+  bcc SKIP@
+  adca #6     ; Add offset to "A" in ascii
+SKIP@
+  rts
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; BUZBEE Tokenizing Routines
 ;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
@@ -144,44 +180,126 @@ NEXTC@
   bne NEXTC@         ;  No? loop
   rts
 
-; Maps a command hash to a command index, and executes it
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; BUZBEE IF Handling Functions
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+; Executes a command based on the initial token
 ; @corrupts B
-; @param A: input hash
 ; @return X: command data table index
-CALLFROMHASH
+RUNIF
-  ldx #0          ; Counting up from zero
+  ldx #0           ; Counting up from zero
+  lda BBVAR.tokens ; Load token
 NEXTHASH@
-  cmpa BBCHT,x    ; Is this hash our hash?
+  cmpa BBCHT,x     ; Is this hash our hash?
-  beq CALCPTR@    ;  Yes? skip to next step to put ptr in x
+  beq CALCPTR@     ;  Yes? skip to next step to put ptr in x
-  leax 1,x        ; Begin considering next hash
+  leax 1,x         ; Begin considering next hash
-  cmpx BBCHTC     ; Is this the last byte?
+  cmpx BBCHTC      ; Is this the last byte?
-  blo NEXTHASH@   ;  No? try next hash, Yes? fall through
+  blo NEXTHASH@    ;  No? try next hash, Yes? fall through
-  PZSTR EM_BADCMD ; Print an error message
+  PZSTR EM_BADCMD  ; Print an error message
-  lbra IFHELP     ; Proceed to call "HELP"
+  lbra IFHELP      ; Proceed to call "HELP"
 CALCPTR@
-  tfr x,d         ; Swap into d to do a cheap multiply
+  tfr x,d          ; Swap into d to do a cheap multiply
-  asld            ; Cheaply << to get *2, pointer size
+  asld             ; Cheaply << to get *2, pointer size
-  tfr d,x         ; Restore x from d and jump to function at index
+  tfr d,x          ; Restore x from d and jump to function at index
   jmp [BBCMDPTRTBL,x]
 
+; IF pointer table
+BBCMDPTRTBL
+  fdb IFCALL
+  fdb IFHELP
+  fdb IFPEEK
+  fdb IFPOKE
+  fdb IFSREC
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;
 ;; BUZBEE Internal Command Functions
 ;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+; Call a pointer
+IFCALL
+  ldd BBVAR.cbtokens   ; Only jump if three tokens given
+  cmpd #3
+  lbne INVALIDARG
+  jsr [BBVAR.tokens+1] ; Make our jump (doesn't implicitly return)
+  rts
+
 ; Print out a help message
 IFHELP
   PZSTR HELP_MSG
   rts
 
-; Placeholder function labels to make assembler happy before git commit
+; Peek memory
-IFCALL
 IFPEEK
+  ldd BBVAR.cbtokens   ; One 16-bit token given, single peek
+  cmpd #3
+  lblo INVALIDARG      ; Not enough args given
+  bhi SELFORBAC@       ; Select forward or backward peek
+SINGLE@
+  lda [BBVAR.tokens+1] ; Get byte
+  lbsr PBYTE           ; Print peek byte
+  rts
+SELFORBAC@
+  ldd BBVAR.cbtokens   ; Have enough tokens?
+  cmpd #5
+  lbne INVALIDARG      ;  No? bounce out
+  ldd BBVAR.tokens+1   ; Are we forwards (BASE < HIGH)?
+  cmpd BBVAR.tokens+3
+  beq SINGLE@          ; Gracefully handle BASE == HIGH
+  blo PEEKFWD
+  bhi PEEKBACK
+
+; Peek forward
+PEEKFWD
+  ldx BBVAR.tokens+1  ; Get BASE
+NEXT@
+  lda ,x+             ; Get the next byte
+  lbsr PBYTE          ; Print our byte
+  cmpx BBVAR.tokens+3 ; Are we at <HIGH> yet?
+  bne NEXT@           ;  No? loop
+  rts
+
+; Peek backwards
+PEEKBACK
+  ldx BBVAR.tokens+1   ; Get BASE
+PREV@
+  lda 0,x              ; Get current byte
+  leax -1,x            ; Prep for next byte
+  lbsr PBYTE           ; Print our byte
+  cmpx BBVAR.tokens+3  ; Are we at <HIGH> yet?
+  bne PREV@            ;  No? loop
+  rts
+
+; Poke bytes into memory
+; NOTE: Blocks could also use 6309 TFM instruction
 IFPOKE
+  ldx BBVAR.cbtokens      ; Make sure we have enough tokens
+  cmpx #4
+  lblo INVALIDARG
+  leax -3,x               ; Get count of bytes to write into X
+  ldy #0                  ; Setup Y for indexing
+NEXTB@
+  lda BBVAR.tokens+3,y    ; Get source byte to copy
+  sta [BBVAR.tokens+1,y]  ; Copy byte
+  leay +1,y               ; Increment memory indexer
+  leax -1,x               ; Decement byte count
+  cmpx #0                 ; Are we at our last byte?
+  bhi NEXTB@              ;  No? loop
+  rts
+
+; Placeholder function labels to make assembler happy before git commit
 IFSREC
   rts
 
+; Invalid argument IF tail
+INVALIDARG
+  PZSTR EM_MISSINGARG
+  rts
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;
 ;; BUZBEE Strings and Tables
@@ -195,8 +313,6 @@ HELP_MSG
   fcb $0D,$0A
   fcc "CALL <PTR> - Call the pointer given in <PTR> as a subroutine."
   fcb $0D,$0A
-  fcc "EXEC <PTR> - Start program at <PTR>."
-  fcb $0D,$0A
   fcc "HELP [CMD] - Display help, command optional."
   fcb $0D,$0A
   fcc "PEEK <BASE> [<HIGH>] - Read memory at <BASE> to <HIGH>."
@@ -207,13 +323,6 @@ HELP_MSG
   fcb $0D,$0A
   fcb $00
 
-BBCMDPTRTBL
-  fdb IFCALL
-  fdb IFHELP
-  fdb IFPEEK
-  fdb IFPOKE
-  fdb IFSREC
-
 PROMPTLINE
   fcb $0D,$0A,$25,$00 ; CR LF '%' NUL
 
@@ -232,3 +341,6 @@ EM_FIFO
 EM_BADCMD
   fcc "!!! Bad Command Hash !!!"
   fcb $0D,$0A,$00
+EM_MISSINGARG
+  fcc "!!! Missing Arguments !!!"
+  fcb $0D,$0A,$00