Apple-2-SW
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apple2_print_uint16
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Shave off 2 more bytes

This commit is contained in:
Michaelangel007 2017-07-06 15:41:49 -07:00
parent ab3385672b
commit 8b95ff7cf9
3 changed files with 19 additions and 21 deletions
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26
README.md
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@ -1,14 +1,14 @@
# Print unsigned 16-bit
6502 assembly code to print an unsigned 16-bit.
6502 assembly code to print an unsigned 16-bit in decimal.
Features:
* Highly optimized for space
* No zero-page usage [version](print_uint16.s) 81 ($51) bytes
* No zero-page usage [version](print_uint16.s) 79 ($4F) bytes
* With zero-page usage [version](print_uint16_zp.s) 69 ($45) bytes
* With stack var usage [version](print_uint16_sp.s) 83 ($53) bytes
* Only 2 ROM entry points: COUT, SCRN2
* Only 2 ROM entry points used: PRHEXZ, SCRN2
* Includes 7 byte demo
# Machine Code
@ -19,16 +19,16 @@ Sans-Zero-Page version:
```asm
0800:A9 12 A2 34 4C 07 08 8E
0808:57 08 48 A2 00 8E 54 08
0810:8E 55 08 8E 56 08 A2 10
0818:F8 0E 57 08 68 2A 48 A0
0820:FD B9 57 07 79 57 07 99
0828:57 07 C8 D0 F4 CA D0 E9
0830:68 D8 A0 03 B9 53 08 20
0838:41 08 88 D0 F7 8A F0 0E
0840:60 48 20 7B F8 20 4B 08
0848:68 29 0F D0 01 CA E8 F0
0850:EF 4C E5 FD 00 00 00 00
0808:55 08 A2 00 8E 52 08 8E
0810:53 08 8E 54 08 A2 10 F8
0818:0E 55 08 2A 48 A0 FD B9
0820:55 07 79 55 07 99 55 07
0828:C8 D0 F4 68 CA D0 E9 D8
0830:A0 03 B9 51 08 20 3F 08
0838:88 D0 F7 8A F0 0E 60 48
0840:20 7B F8 20 49 08 68 29
0848:0F D0 01 CA E8 F0 EF 4C
0850:E5 FD 00 00 00 00
```
With-Zero-Page version:

BIN
print_uint16
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Binary file not shown.

14
print_uint16.s
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@ -21,12 +21,11 @@ SCRN2 = $F879
; ======================================================================
PrintUint16
STX _temp
PHA ; Optimized: STA _temp+1
LDX #0
STX _bcd+0
STX _bcd+1
STX _bcd+2
LDX #0 ; Optional 65C02 version
STX _bcd+0 ; STZ _bcd+0
STX _bcd+1 ; STZ _bcd+1
STX _bcd+2 ; STZ _bcd+2
Dec2BCD
LDX #16 ; 16 bits
@ -35,9 +34,8 @@ _Dec2BCD ; https://en.wikipedia.org/wiki/Double_dabble
ASL _temp+0 ; abcd efgh | ijkl mnop |
; ROL _temp+1 ; C=a bcde fghi | jklm nop0 |
; ; Bit 7654_3210 | 7654_3210 |
PLA
ROL
PHA
PHA ; Optimized: STA _temp+1
LDY #$FD ; $00-$FD=-3 bcd[0] bcd[1] bcd[2] bcd[3]
_DoubleDabble ; Y=FD Y=FE Y=FF Y=00
@ -46,10 +44,10 @@ _DoubleDabble ; Y=FD Y=FE Y=FF Y=00
STA _bcd-$FD,Y
INY
BNE _DoubleDabble
PLA
DEX
BNE _Dec2BCD
PLA ; keep stack
CLD ; X=0 = output length
DecWidth