Forth: Add DEC. (Print unsigned decimal number)

forth.s

@@ -170,6 +170,9 @@ RES_vec:
 	; clear the OK flag
 	stz OK
 
+  ; clear the PRT0 flag (print leading 0)
+  stz PRT0
+
 ; This is a Direct Threaded Code based FORTH
 
 ; Load the entry point of our main FORTH
@@ -374,6 +377,27 @@ noheader "FETCH_OK"
 	stz 1,x
 	JMP DEX2_NEXT
 
+defword "DECPRINT","DEC.",
+; ( n -- )
+; Print the number in decimal form
+	LDA 2,x
+	STA BIN+0
+	LDA 3,x
+	STA BIN+1
+	JSR hex16toBCD
+	LDY #5
+	STY PRT0	; 6 digits, so 6-1=5 where we don't want to print leading 0
+	LDA BCD+2
+	JSR print_byte
+	LDA BCD+1
+	JSR print_byte
+	LDA BCD+0
+	JSR print_byte
+	STZ PRT0	; reset the PRT0 flag
+	LDA #' '
+	JSR putc
+	JMP do_DROP
+
 defword "COLON",,
 ; push IP to Return Stack
 	LDA IP+1	; HI
@@ -2668,21 +2692,25 @@ print_byte:
 	LSR	; to get HI nibble
 	LSR
 	LSR
-	JSR nibble_value_to_asc
-	JSR putc
-
+	JSR print_nibble
 	PLA
 	AND #$0F ; LO nibble
-	JSR nibble_value_to_asc
-	JSR putc
+	JSR print_nibble
 	RTS
 
-nibble_value_to_asc:
+print_nibble:
+	BNE :+
+	; digit is a 0
+	DEC PRT0
+	BPL :++		; PRT0>0 --> we don't print it
+:	STZ PRT0	; digit wasn't 0, so we clear PRT0 flag
 	CMP #$0A
 	BCC @skip
 	ADC #$66
 @skip:
 	EOR #$30
+	JSR putc
+:
 	RTS
 
 nibble_asc_to_value:
@@ -2710,6 +2738,32 @@ nibble_asc_to_value:
 	CLC
 	RTS
 
+hex16toBCD:
+; http://www.6502.org/source/integers/hex2dec-more.htm
+; expect  a 16-bit HEX number in BIN+{0,1}
+; returns a 24-bit BCD number in BCD+{0,1,2}
+	SED			; Switch to decimal mode
+	STZ BCD+0	; we erase the result area
+	STZ BCD+1
+	STZ BCD+2
+	LDY #16		; The number of source bits
+@cnvbit:
+	ASL BIN+0	; Shift out one bit
+	ROL BIN+1
+	LDA BCD+0	; And add into result
+	ADC BCD+0
+	STA BCD+0
+	LDA BCD+1	; propagating any carry
+	ADC BCD+1
+	STA BCD+1
+	LDA BCD+2	; ... thru whole result
+	ADC BCD+2
+	STA BCD+2
+	DEY			; And repeat for next bit
+	BNE @cnvbit
+	CLD			; Back to binary
+	RTS
+
 ; Interrupts routines
 
 IRQ_vec:
@@ -2868,7 +2922,11 @@ INP_LEN:  .res 1	; Length of the text in the input buffer
 INPUT:	  .res 128	; CMD string (extend as needed, up to 256!)
 INP_IDX:  .res 1	; Index into the INPUT Buffer (for reading it with KEY)
 OK:		  .res 1	; 1 -> show OK prompt
+PRT0:  .res 1  ; flag we use to know if we print leading zeros. <0 we print the 0, otherwise we don't
+SCRATCH: .res 8  ; 8 bytes we can use in routines...
+
+BIN = SCRATCH
+BCD = SCRATCH+2
 
 ; Base of user memory area.
 USER_BASE:
-