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Shave off 2 more bytes
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README.md
26
README.md
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@ -1,14 +1,14 @@
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# Print unsigned 16-bit
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6502 assembly code to print an unsigned 16-bit.
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6502 assembly code to print an unsigned 16-bit in decimal.
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Features:
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* Highly optimized for space
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* No zero-page usage [version](print_uint16.s) 81 ($51) bytes
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* No zero-page usage [version](print_uint16.s) 79 ($4F) bytes
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* With zero-page usage [version](print_uint16_zp.s) 69 ($45) bytes
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* With stack var usage [version](print_uint16_sp.s) 83 ($53) bytes
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* Only 2 ROM entry points: COUT, SCRN2
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* Only 2 ROM entry points used: PRHEXZ, SCRN2
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* Includes 7 byte demo
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# Machine Code
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@ -19,16 +19,16 @@ Sans-Zero-Page version:
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```asm
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0800:A9 12 A2 34 4C 07 08 8E
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0808:57 08 48 A2 00 8E 54 08
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0810:8E 55 08 8E 56 08 A2 10
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0818:F8 0E 57 08 68 2A 48 A0
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0820:FD B9 57 07 79 57 07 99
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0828:57 07 C8 D0 F4 CA D0 E9
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0830:68 D8 A0 03 B9 53 08 20
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0838:41 08 88 D0 F7 8A F0 0E
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0840:60 48 20 7B F8 20 4B 08
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0848:68 29 0F D0 01 CA E8 F0
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0850:EF 4C E5 FD 00 00 00 00
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0808:55 08 A2 00 8E 52 08 8E
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0810:53 08 8E 54 08 A2 10 F8
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0818:0E 55 08 2A 48 A0 FD B9
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0820:55 07 79 55 07 99 55 07
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0828:C8 D0 F4 68 CA D0 E9 D8
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0830:A0 03 B9 51 08 20 3F 08
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0838:88 D0 F7 8A F0 0E 60 48
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0840:20 7B F8 20 49 08 68 29
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0848:0F D0 01 CA E8 F0 EF 4C
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0850:E5 FD 00 00 00 00
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```
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With-Zero-Page version:
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BIN
print_uint16
BIN
print_uint16
Binary file not shown.
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; ======================================================================
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PrintUint16
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STX _temp
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PHA ; Optimized: STA _temp+1
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LDX #0
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STX _bcd+0
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STX _bcd+1
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STX _bcd+2
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LDX #0 ; Optional 65C02 version
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STX _bcd+0 ; STZ _bcd+0
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STX _bcd+1 ; STZ _bcd+1
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STX _bcd+2 ; STZ _bcd+2
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Dec2BCD
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LDX #16 ; 16 bits
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@ -35,9 +34,8 @@ _Dec2BCD ; https://en.wikipedia.org/wiki/Double_dabble
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ASL _temp+0 ; abcd efgh | ijkl mnop |
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; ROL _temp+1 ; C=a bcde fghi | jklm nop0 |
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; ; Bit 7654_3210 | 7654_3210 |
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PLA
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ROL
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PHA
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PHA ; Optimized: STA _temp+1
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LDY #$FD ; $00-$FD=-3 bcd[0] bcd[1] bcd[2] bcd[3]
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_DoubleDabble ; Y=FD Y=FE Y=FF Y=00
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STA _bcd-$FD,Y
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INY
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BNE _DoubleDabble
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PLA
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DEX
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BNE _Dec2BCD
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PLA ; keep stack
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CLD ; X=0 = output length
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DecWidth
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