Apple-2-SW/apple2_print_uint16
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Optimized down to 91 bytes

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Michaelangel007 2017-07-05 23:08:47 -07:00
parent 1ce8c90bde
commit c9ffff1961
3 changed files with 29 additions and 25 deletions
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26
README.md
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@ -1,6 +1,6 @@
# Print unsigned 16-bit
6502 assembly code to print an unsigned 16-bit in 95 bytes ($5F).
6502 assembly code to print an unsigned 16-bit in 91 bytes ($5B).
Features:
@ -14,18 +14,18 @@ Copy/Paste into your favorite emulator.
```asm
0800:A9 12 A2 34 4C 07 08 8E
0808:64 08 8D 65 08 A9 00 8D
0810:60 08 8D 61 08 8D 62 08
0818:A2 10 F8 0E 64 08 2E 65
0820:08 A0 FD B9 63 07 79 63
0828:07 99 63 07 C8 D0 F4 CA
0830:D0 E9 D8 A0 03 B9 5F 08
0838:20 44 08 88 D0 F7 8A E0
0840:00 F0 11 60 48 20 7B F8
0848:20 4E 08 68 29 0F D0 04
0850:E0 00 F0 EF C9 0A 90 02
0858:69 06 69 B0 E8 4C ED FD
0860:00 00 00 00 00 00
0808:61 08 48 A2 00 8E 5D 08
0810:8E 5E 08 8E 5F 08 A2 10
0818:F8 0E 61 08 68 2A 48 A0
0820:FD B9 60 07 79 60 07 99
0828:60 07 C8 D0 F4 CA D0 E9
0830:68 D8 A0 03 B9 5C 08 20
0838:41 08 88 D0 F7 8A F0 11
0840:60 48 20 7B F8 20 4B 08
0848:68 29 0F D0 04 E0 00 F0
0850:EF C9 0A 90 02 69 06 69
0858:B0 E8 4C ED FD 00 00 00
0860:00 00
```

BIN
print_uint16
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28
print_uint16.s
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@ -17,20 +17,24 @@ SCRN2 = $F879
; Also see: Applesoft LINPRT @ ED24
; ======================================================================
PrintUint16
STX _temp+0
STA _temp+1
STX _temp
PHA ; Optimized: STA _temp+1
LDA #0
STA _bcd+0
STA _bcd+1
STA _bcd+2
LDX #0
STX _bcd+0
STX _bcd+1
STX _bcd+2
Dec2BCD
LDX #16 ; 16 bits
SED ; "Double Dabble"
_Dec2BCD ; https://en.wikipedia.org/wiki/Double_dabble
ASL _temp+0
ROL _temp+1
ASL _temp+0 ; abcd efgh | ijkl mnop |
; ROL _temp+1 ; C=a bcde fghi | jklm nop0 |
; ; Bit 7654_3210 | 7654_3210 |
PLA
ROL
PHA
LDY #$FD ; $00-$FD=-3 bcd[0] bcd[1] bcd[2] bcd[3]
_DoubleDabble ; Y=FD Y=FE Y=FF Y=00
@ -39,9 +43,10 @@ _DoubleDabble ; Y=FD Y=FE Y=FF Y=00
STA _bcd-$FD,Y
INY
BNE _DoubleDabble
DEX
BNE _Dec2BCD
PLA ; keep stack
CLD ; X=0 = output length
DecWidth
@ -52,8 +57,7 @@ BCD2Chars
DEY
BNE BCD2Chars
TXA
CPX #0 ; Handle special case input = $0000 of no output
TXA ; Handle special case input = $0000 of no output
BEQ _HaveLeadingDigit
_PrintDone
@ -84,5 +88,5 @@ PutChar
JMP COUT
_bcd ds 4 ; 6 chars for printing dec
_temp db 0,0
_temp db 0