;- 5 Snowflake (Amstrad CPC/Z80 Assembler) by Overflow/Logon System (37) org #0A02 db %01000000 db %10001010 db %00001100 db %01001110 db %10010000 db %00100000 db %01001001 db %10010010 ; from basic CALL &0A0A=DE ld l,e loop_l ld h,d ld e,(hl) loop_h_b ld a,20 sub l ld l,h ld h,a ld (#B726),hl ld a,"*" call #BB5A djnz loop_h_b no_star sla e dec h jr c,loop_h_b jr nz,no_star dec l jr nz,loop_l ret - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ;- 8 Snowflake (Amstrad CPC/Z80 Assembler) by Longshot / Logon System (45) ;;======================================================================= ;; Vintage Computing Christmas Challenge 2025 (VC3 2025) ;; Amstrad CPC / Longshot (Logon System) ;; December 2025 ;; 45 bytes ;; Brute Force Mode! ;; run from basic : memory &1f00:mode 0:load "vcc2025.bin":call #abe ;; or type : run "STUB" with the same content ;;======================================================================= _size_code equ _end_code-_start_code org_code equ #2100-47 ; Raw_Pattern end at #20fe (bc=20ff) hirom_display equ #c38b ; Rom string display (input hl=ptr string) firm_display equ #bb5a ; Firmware Display Char (input acc=ascii char) ; Register de=#0abe / bc=#20ff / hl=00xx / Zf=1 Cf=0 org org_code run $ _start_code ; adr of call=>>DE >> #0abe (#0a=calc char "*", #be>>end of buffer) ld h,b ; h=#20xx (xx=b for up ptr, de=down ptr) byte_roll dec c ; #20fe start of pattern table scf ; Cf=1 injected in pattern rolled byte to test reload condition bit_roll ld l,c ; hl=ptr on Raw pattern corrected rl (hl) ; Get Cf from pattern (1=star;0=space) jr z,byte_roll ; if (hl)==0 last bit was treated, reload sbc a,a ; if Cf=1, acc=#ff , else acc=0 and d ; acc=#0a if #ff, else 0 add a,h ; acc=#2a ("*") if Cf was 1, else #20 (" ") dec e ; Ptrbuf-- ld l,e ; ld (hl),a ; store char call nz,#bb5a ; Don't display the last char jr nz,bit_roll ; rst #10 ; Try to display (but fail a lot..) defw hirom_display ; Display the "reverse" buffer Raw_Pattern ; start at x=10 >> pattern byte #ff became #e0=ret po db #ff,#8f ; Pattern 20 bits / line db #e4,#24 db #24,#95 db #04,#48 db #02,#40 db #4e,#80 db #53,#39 db #30,#84 db #81,#e2 db #28,0 db #15,0 db #40 _end_code - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ;- 9 Snowflake (Amstrad CPC/Z80 Assembler) by Arnolde of Leosoft (48) ;execution: ;CALL #140A begin equ #1402 ;CPC 6128 values: TXT_CURSOR equ #B726 TXT_OUTPUT equ #BB5A ;SNOWFLAKE BITMAP: ;db 00000000* ;this one is used but not explicitly stored org begin db %00000010; * db %01010001;* * * db %00110000; ** db %01110010; * *** db %00001001;* * db %00000100; * db %10010010; * * * db %01001001;* * * db %11111111;********* ;the execution begins here with a harmless RST#38 ; * * *** * * ; * * * * * * * ; * * * ; * *** * ; *** * * * *** ; ** * ** ; * * *** * * ; * * * ; * ;the flake is plotted around the center 10,10 (locate 11,11 in basic) ;initial conditions: ;DE=#140A (calling address from basic) ;D=20 used to mirror the coordinates, E=10 used for initialization of loops ;H=1 because called from basic ;set coords for the 2 right/leftmost points ld l,e ;y = 10 call plot_two_stars ;draw right/leftmost points ;run through y and x from 10 to 1 loop_y: ld b,e ;x = 10 scf ;first one (x=10) is always plotted (vertical axis) loop_x: ld h,b ;h = x for plotting call c,plot_four_stars ld h,d ;h = highbyte of the bitmap table srl (hl) ;shift next bit, replace by 0 for outer edges djnz loop_x dec l jr nz,loop_y ret plot_four_stars: call mirror_y_and_plot_two_stars mirror_y_and_plot_two_stars: ld a,d sub l ld l,a plot_two_stars: call mirror_x_and_plot_one_star mirror_x_and_plot_one_star: ld a,d sub h ld h,a ;plot one star ld (TXT_CURSOR),hl ;locate ld a,"*" jp TXT_OUTPUT ;plot length equ $-begin ;48 bytes - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ;- 23 Snowflake (Amstrad CPC/Z80 Assembler) by Gallegux (62) ;; Snowflake62 by Gallegux ;; size: 62 bytes ;; execution from basic: CALL &173E ;; A=0 B=20 C=FF D=17 E=3E H=00 L=4? org #9900 ld a,b ld c,d ld ix, eliro+360 ld hl, enirejo ld d,h .py ld b,8 .pi rlc (hl) jr nc, konservi xor a, #A .konservi ld (de),a inc de ld (ix),a dec ix djnz pi inc hl dec c jr nz, py rst #28 dw #6fc enirejo db #00,#60,#00,#3F,#00,#F2,#4F,#0A db #31,#42,#5F,#A4,#0D,#2C,#00,#DB db #03,#6F,#DB,#36,#96,#D0,#00 db #1A,#15,#27,#01,#19 eliro - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ;- 28 Snowflake (Amstrad CPC/Z80 Assembler) by gurneyh (65) ; VCCC 2025 - Amstrad CPC - 65 bytes - CALL #1314 TXT_OUTPUT equ #BB5A org #1300 bitmap db #00,#40,#01,#40,#28,#C0,#18,#40,#39,#40 db #04,#C0,#02,#40,#49,#40,#24,#C0,#FF,#C0 start ld h,d : ld c,d : ld e,10 lines ld a,d : sub c : cp e : jr c,ul : ld a,c : dec a ul add a,a : ld l,a : ld a,(hl) : inc l : ld l,(hl) : ld h,a ld a,' ' : push af : ld b,e left add hl,hl : sbc a,a : and e : add a,' ' : push af : call TXT_OUTPUT : djnz left pop af : ld b,e right pop af : call TXT_OUTPUT : djnz right ld h,d : dec c : jr nz,lines : ret print "SIZE: ", $ - bitmap, " bytes" save "vccc.bin", bitmap, $ - bitmap, DSK, "vccc.dsk" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ;- 42 Snowflake (Amstrad CPC/Z80 Assembler) by issalig (77) ; * ; * * * ; * * *** * * ; ** * ** ; *** * * * *** ; * *** * ; * * * ; * * * * * * * ; * * *** * * ;******************* ; * * *** * * ; * * * * * * * ; * * * ; * *** * ; *** * * * *** ; ** * ** ; * * *** * * ; * * * ; * ; ============================================================================= ; Vintage Computing Christmas Challenge 2025 (VCCC 2025) ; Z80 assembly for Amstrad CPC - Snowflake ; works with pasmo or winape ; size. 77 bytes ; author. issalig ; ============================================================================= ;write "vc3.bin" ORG #8000 PRINT_CHAR EQU #BB5A START: ; Initialize Y counter to -9 (Top of the grid) LD C, -9 Y_LOOP: ; Initialize X counter to -9 (Left of the grid) LD B, -9 X_LOOP: ; --- 1. Calculate Absolute Coordinates for Symmetry --- ; The snowflake is symmetric. We map (-9..9) to (9..0..9). ; This allows us to store data for only one quadrant. LD A, C CALL ABS LD E, A ; E = ABS(Y) = Row Index (0-9) LD A, B CALL ABS LD D, A ; D = ABS(X) = Column Index (0-9) ; --- 2. The Center Cross Rule --- ; If we are on the X axis (Y=0) or Y axis (X=0), always print '*' ; Check if D (ABS(X)) is zero OR A ; A currently holds D from previous block JR Z, STAR ; If X=0, jump to print star ; Check if E (ABS(Y)) is zero LD A, E OR A JR Z, STAR ; If Y=0, jump to print star ; --- 3. Data Lookup --- ; We need to check the pattern for the current row E. ; DATA_TABLE stores patterns for rows 1 to 9. ; We calculate address HL = DATA_TABLE + (E - 1) LD HL, DATA_TABLE-1 ; Base address minus 1 ADD A, L ; Add E (in A) to L LD L, A ; HL now points to the byte for this row ; --- 4. Bitmask Generation --- ; We need to check if the bit corresponding to column D is set. ; We generate a mask 2^(D-1) efficiently. ; Example If D=1, mask=1. If D=3, mask=4. XOR A ; A = 0 SCF ; Set Carry Flag = 1 SHIFT: ADC A, A ; Shift Left Bit 0 gets Carry (1), others 0 DEC D ; Loop D times JR NZ, SHIFT ; Now A contains the bitmask (e.g., 00000100) ; --- 5. Pixel Decision --- AND (HL) ; Check if the bit is set in the data byte LD A, ' ' ; Default to Space JR Z, PRNT ; If result is 0, print Space STAR: LD A, '*' ; Otherwise, load Star PRNT: CALL PRINT_CHAR ; Print the character ; --- 6. Loop Control (X Axis) --- INC B ; Move to next column LD A, B CP 10 ; Have we reached the end (+9)? JR NZ, X_LOOP ; If not, continue row ; --- 7. Newline --- ;LD A, 10 ; LF (Line Feed) not needed as after CP 10 A is 10 CALL PRINT_CHAR LD A, 13 ; CR (Carriage Return) CALL PRINT_CHAR ; --- 8. Loop Control (Y Axis) --- INC C ; Move to next row LD A, C CP 10 ; Have we reached the bottom (+9)? JR NZ, Y_LOOP ; If not, continue grid RET ; --- Helper Function Absolute Value --- ; Input A (signed 8-bit) ; Output A (positive 8-bit) ABS: OR A ; Update flags based on A RET P ; Return if Positive (Sign bit clear) NEG ; Negate (Two's complement) if Negative RET ; --- Data Table --- ; Bit patterns for rows 1 to 9 (Row 0 is handled by logic). ; Each bit represents a star position. ; 73 = 01001001 -> Stars at positions 1, 4, 7 DATA_TABLE: DB 73, 146, 4, 9, 114, 48, 81, 2, 0 END - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ;- 44 Snowflake (Amstrad CPC/Z80 Assembler) by BSC (79) ; ; DEFINES ; txtout equ $bb5a ROW1 equ %00000010 ; = 2 ROW2 equ %01010001 ROW3 equ %00110000 ROW4 equ %01110010 ROW5 equ %00001001 ROW6 equ %00000100 ROW7 equ %10010010 ROW8 equ %01001001 org BASE ; see Makefile db 0 ; this can be stored implicitly ; i.e. it does not have to be part of the file/data generator rows: db ROW1,ROW2,ROW3,ROW4,ROW5,ROW6,ROW7,ROW8 ; ; IDEAS ; ; Use H and L as indices into the patterns ; and D and E as offsets to add to HL after ; each row. ; can we use the RES b,r trick (see dancedance.z80 aka heartbel) ; ; CODE ; ; CALL <nnnn> from Basic sets Z80 DE register to <nnnn>. ; i.e. DE=&202a ; HL = 68 = 0x0044 ; regs: ; A=char, B=column counter, C=pattern bitmap, D=row counter, E=&2a = '*' ; HL=pattern ptr where H=&20 = ' ' ; D and H are both $20 here ; print upper part ld hl, rows-1 ; the byte before "rows" must be zero! call print_rows call long_line ; print lower part ld a,$2b ; dec hl ld (inc_or_dec),a dec hl print_rows: ld d,9 rows_loop: ; load pattern ld c,(hl) ; print left part with leading space ld a,h ; $20 call print_row_half ; inject RR C to print reversed ld a,$19 ld (rotate+1),a ; prints middle column: '*' ; and right part (=left part reversed) ld a,e ; star call print_row_half call crlf ; inject RL C again ld a,$11 ld (rotate+1),a ; next/previous row inc_or_dec: inc hl ; or dec hl dec d jr nz,rows_loop ret long_line: ; print long middle line ld a,e ; $2a ld b,19 ; = 0x13 middle_line: call $bb5a djnz middle_line crlf: rst $18 dw rom_addr_crlf ret ; ' ' = 32 = 0x20 = %00100000 ; '*' = 42 = 0x2a = %00101010 ; prints the pattern once, making half a row (without the middle column) print_row_half: ; print what was in A ; A=char, B=loop cnt, C=bitmap, D=outer loop cnt, E='*', H=' ', L=pattern ptr ld b,9 print_loop: call $bb5a ld a,h ; = 32 = 0x20 = %00100000 rotate: rl c ; cb 11 jr nc,skip ld a,e; = 42 = 0x2a = %00101010 = '*' skip: djnz print_loop ret ; ; DATA ; rom_addr_crlf: dw $c3e2 ; = print CRLF ; db 0 ; this can be stored implicitly, see above - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ;- 60 Snowflake (Amstrad CPC/Z80 Assembler) by lightforce6128 (87) NOLIST SCR_SET_MODE EQU #BC0E ;; A=mode TXT_OUTPUT EQU #BB5A ;; A=character EXPECTED_ADDRESS EQU #5204 ORG EXPECTED_ADDRESS RUN winape_entry program_begin: ;; Store a pattern that is used multiple times. ;; ;; Input: ;; A - Symbol to store. ;; HL - Row and column of upper left symbol. ;; ;; Changes: ;; H - Incremented by one. print_pattern: IF2 : IF $ - EXPECTED_ADDRESS PRINT "Routine 'print_pattern' needs to be located at #$EXPECTED_ADDRESS, but is at #$print_pattern." STOP ENDIF : ENDIF LD (HL),A : INC H : INC L ;; 3 ;; 1 LD (HL),A : INC H : INC L ;; 3 ;; |\ LD (HL),A : DEC L ;; 2 ;; | 2 LD (HL),A : DEC L ;; 2 ;; | \ LD (HL),A : DEC H : DEC H ;; 3 ;; 5-4-3 RET ;; 1 ;; ;; ;; -- ;; ;; ;; 14 ;; program_entry: ;; AF:FFA4 HL:ABFF DE:0040 BC:B0FF IX:B0A0 IY:0000 ;; ^^^^ ;; Redirect (in this program) unused restart 5/#28 to pattern printing routine. LD HL,print_pattern : LD (#29),HL ;; 6 ;; Only store address, jump command is already there. ;; ;; -- ;; ;; ;; 6 ;; ;; Prepare octant (upper left quarter, lower triangle). ;; The range #xxyy with xx,yy from [1,19] is filled with zeros. ASTERISK EQU #2A ;; - ;; LD A,ASTERISK ;; 2 ;; Store character to print in A. ADD HL,BC : RST #28 ;; 2 ;; Store pattern for position 3|3. (HL+BC=#0303) ADD HL,HL : LD (HL),A ;; 2 ;; Store single star for position 6|6. INC H : INC L : LD (HL),A ;; 3 ;; Store single star for position 7|7. INC H : INC L : RST #28 ;; 4 ;; Store pattern for position 8|8. LD L,5 : RST #28 ;; 3 ;; Store pattern for position 8|5. LD L,2 : RST #28 ;; 3 ;; Store pattern for position 8|2. LD HL,#0A01 : LD (HL),A ;; 4 ;; Store single star for position 10|1. ;; ;; -- ;; ;; ;; 23 ;; ;; AF:2A0A HL:0A01 DE:0040 BC:B0FF IX:B0A0 IY:0000 ;; (^^) ^^ (^^) ;; Mirror prepared octant to other octants and quadrants. ;; The order is important: Because the loop runs backwards, ;; the needed parts of the upper triangle are available. LD D,H ;; 1 ;; Store constant #0A. LD B,D ;; 1 ;; Row in upper left quadrant. m__y_loop: ;; - ;; LD C,D ;; 1 ;; Column in upper left quadrant. m__x_loop: ;; - ;; LD A,C : CP A,B ;; 2 ;; Lower or upper triangle? LD A,(BC) ;; 1 ;; Already load stored value to A. JR NC,m__skip ;; 2 ;; LD H,C : LD L,B : LD (HL),A ;; 3 ;; If in lower triangle, mirror to upper triangle. m__skip: ;; - ;; LD H,D : LD L,D : ADD HL,HL : SBC HL,BC ;; 5 ;; Calculate inverse row and column in HL. LD (HL),A ;; 1 ;; Mirror to lower right quadrant. PUSH HL : LD H,B : LD (HL),A : POP HL ;; 4 ;; Mirror to upper right quadrant. LD L,C : LD (HL),A ;; 2 ;; Mirror to lower left quadrant. DEC C : JR NZ,m__x_loop ;; 3 ;; DJNZ m__y_loop ;; 2 ;; ;; ;; -- ;; ;; ;; 28 ;; ;; AF:0042 HL:1301 DE:0A40 BC:0000 IX:B0A0 IY:0000 ;; ^^ ;; Transfer completed pattern from memory to screen. LD B,H ;; 1 ;; Row in all quadrants. t__y_loop: ;; - ;; LD C,H ;; 1 ;; Column in all quadrants. t__x_loop: ;; - ;; LD (#B726),BC ;; 4 ;; Position cursor. LD A,(BC) : CALL TXT_OUTPUT ;; 4 ;; Print star on screen. DEC C : JR NZ,t__x_loop ;; 3 ;; DJNZ t__y_loop ;; 2 ;; ;; ;; -- ;; ;; ;; 15 ;; ;; A:0042 HL:1301 DE:0A40 BC:0000 IX:B0A0 IY:0000 ;; ;; Wait forever. JR $ ;; 2 ;; ;; ;; -- ;; ;; ;; 2 ;; program_end: ;; Entry point for WinAPE assembler. winape_entry: ;; Clear screen. This is automatically done when program was loaded from file. LD A,1 : CALL SCR_SET_MODE ;; Set second register set as it is set when loaded from file. ;; NOTE: As long as interrupts are running, this cannot be used. ;;EX AF,AF' : EXX ;; LD HL,8D8C : PUSH HL : POP AF ;; LD HL,#B8D9 ;; LD DE,#8020 ;; LD BC,#7F8D ;;EX AF,AF' : EXX ;; Set first register set as it is set when loaded from file. LD HL,#FFA4 : PUSH HL : POP AF LD HL,#ABFF LD DE,#0040 LD BC,#B0FF LD IX,#B0A0 LD IY,#0000 ;;LD SP,#BFFA CALL program_entry ;; If the program returns, the computer will be reset. RST #00 IF2 program_size EQU program_end - program_begin PRINT "Program size: &program_size bytes" PRINT 'SAVE"snow.bin",B,&program_begin,&program_size,&program_entry' ENDIF