Routines
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F220: 128K mode routines and data
This is relocated to $8014/load_stage onwards during init (926 bytes long).
page_in_stage_128k F220 LD A,($8007) Load wanted_stage_number
F223 LD HL,$A13A Address of current_stage_number
F226 CP (HL) Return if the stage is already loaded
F227 RET Z
F228 LD (HL),A wanted_stage_number = current_stage_number
Copy the stage data from the correct bank and address to $5C00..$76EF.
F229 ADD A,A Point HL at stage_data_locations[current_stage_number]
F22A LD B,$00
F22C LD C,A
F22D LD HL,$8037
F230 ADD HL,BC
F231 LD A,(HL) Load paging flags byte
F232 INC HL HL++
F233 LD H,(HL) HL = Source data address (B is zero)
F234 LD L,B
F235 LD BC,$7FFD 128K: Page in required bank
F238 OUT (C),A
F23A LD DE,$5C00 Destination $5C00..$76EF (from the horizon backdrop to just before the turbo icons)
F23D LD BC,$1AF0 Bytes to copy (worst case)
F240 LDIR Copy
F242 JP $8208 Exit via relocated reset_paging_128k
Pairs of (top byte of source data address, paging flags).
stage_data_locations F245 DEFW $C001 Level 1. Source = $C000, Paging = bank 1
F247 DEFW $E001 Level 2. Source = $E000, Paging = bank 1
F249 DEFW $C006 Level 3. Source = $C000, Paging = bank 6
F24B DEFW $E006 Level 4. Source = $E000, Paging = bank 6
F24D DEFW $C007 Level 5. Source = $C000, Paging = bank 7
F24F DEFW $E007 Level 6. Source = $E000, Paging = bank 7
$8045 once relocated.
start_siren_hook_128k F251 LD A,$8C Store $8C to channel A fine pitch
F253 LD ($A213),A
F256 LD A,$0E Store 14 to channel A volume (4-bit)
F258 LD ($A21B),A
F25B SUB $02 Store 12 to channel B volume
F25D LD ($A21C),A
F260 LD A,$AA Self modify 'LD A,x' @ F271 (in this position)
F262 LD ($8066),A
F265 LD ($A239),A var_a239 = $AA
F268 RET Return
engine_sfx_play_hook_128k F269 LD A,($A239) var_a239 (initialised to $AA above)
F26C AND A Return if zero
F26D RET Z
F26E LD A,($A213) Load channel A fine pitch
F271 LD B,$AA jump on 50-50 alternating pattern? -- could be flipping between string sets?
F273 RLC B
F275 JR C,f27f_128k
Decreasing case
F277 SUB $03 A -= 3
F279 CP $5A Jump if A >= $5A
F27B JR NC,f28b_128k
F27D JR f285_128k Jump
Increasing case
f27f_128k F27F ADD A,$03 A += 3
F281 CP $8C Jump if A < $8C
F283 JR C,f28b_128k
Arrive here if A is outside of $5A..$8B
f285_128k F285 EX AF,AF'
F286 LD A,B Store B (rotating pattern)
F287 LD ($8066),A
F28A EX AF,AF'
Arrive here if A is $5A..$8B
f28b_128k F28B LD ($A213),A Update channel A fine pitch
F28E SUB $04 and store 4 less to channel B fine pitch
F290 LD ($A215),A
F293 LD A,($A21A) Set mixer to enable tone A & B
F296 AND $3C
F298 LD ($A21A),A
F29B JR write_registers_hook_128k Jump
silence_audio_hook_128k F29D LD A,$3F Initialise mixer to $3F (all noise and tone off)
F29F LD ($A21A),A
writing the full register set?
write_registers_hook_128k F2A2 LD HL,$A21E Address of sound register value(s) -- other values must be earlier
F2A5 LD A,$0B Select AY-3-8912 sound chip register 11: envelope fine duration
F2A7 LD C,$FD
write_registers_hook_loop F2A9 LD B,$FF
F2AB OUT (C),A
F2AD LD B,$BF Write to the register from (HL), then decrement B and HL
F2AF OUTD
F2B1 DEC A Next register down
F2B2 JP P,sub_809D Loop to write_registers_hook_loop while +ve
F2B5 RET Return
f2b6_128k F2B6 LD HL,($A24A) Get speed value
F2B9 RR H A = speed / 2 (top half)
F2BB LD A,L A = speed / 2 (bottom half)
F2BC RRA
F2BD CPL L = ~A
F2BE LD L,A
F2BF LD A,($A253) Jump if in low gear
F2C2 AND A
F2C3 JR Z,page_in_stage_128k_0
F2C5 SLA L
F2C7 RL H
page_in_stage_128k_0 F2C9 SLA L
F2CB RL H
F2CD SLA L
F2CF RL H
F2D1 LD A,($A23B) A = tunnel_sfx
F2D4 AND A Set flags
F2D5 LD DE,$0190 -- base tone value?
F2D8 LD A,$0F
F2DA JR Z,page_in_stage_128k_1 Jump if tunnel_sfx was zero
F2DC LD DE,$0258 -- base tone value?
F2DF LD A,$0C Volume = 12
page_in_stage_128k_1 F2E1 ADD HL,DE -- speed value + base tone?
F2E2 LD ($A217),HL Set channel C pitch (both fine and course)
F2E5 LD ($A21D),A Set channel C volume
F2E8 LD A,($A21A) Set mixer to enable tone C
F2EB AND $3B
F2ED LD ($A21A),A
F2F0 RET Return
turbo_sfx_play_hook_128k F2F1 LD A,$3C Set noise pitch (5-bit) [$3C is > 5-bit...]
F2F3 LD ($A219),A
F2F6 LD ($A23A),A var_a23a = $3C -- Copy of it?
F2F9 RET Return
engine_sfx_setup_hook_128k F2FA LD A,($A23A) Jump if var_a23a is zero
F2FD AND A
F2FE JR Z,f2b6_128k
F300 DEC A Decrement noise pitch
F301 RET Z Return if zero
F302 LD HL,$A219 Address of noise pitch register soft copy
F305 DEC (HL) Decrement in-place
F306 JR Z,f31f_128k Jump if zero
F308 LD A,(HL) Increment noise pitch register soft copy by 10
F309 ADD A,$0A
F30B LD L,A
F30C LD H,$00
F30E LD ($A217),HL Set channel C pitch (both fine and course)
F311 LD A,($A21A) Set mixer to enable tone C and noise C
F314 AND $1B
F316 LD ($A21A),A
F319 LD A,$0D Set channel C volume to 13
F31B LD ($A21D),A
F31E RET Return
f31f_128k F31F LD A,($A21A) Set mixer to disable tone C and noise C
F322 OR $24
F324 LD ($A21A),A
F327 XOR A var_a23a = 0
F328 LD ($A23A),A
F32B JP load_stage_7 Exit via f2b6_128k
Relocated to $8122
"Giddy up boy!"
speech_samples_table F32E DEFW $0A8C length
F330 DEFW $C000 address
"Let's go Mr. Driver!"
F332 DEFW $14E6 length
F334 DEFW $CA8C address
"Hold on man!"
F336 DEFW $0A5A length
F338 DEFW $DF72 address
"Your time's up"
F33A DEFW $0ABE length
F33C DEFW $E9CC address
Start noise
F33E DEFW $0ADC length
F340 DEFW $F48A address
play_speech_128k F342 EX AF,AF' Bank input index (sample indices are 1..5)
F343 CALL load_stage_6 Call silence_audio_hook_128k
F346 LD A,$04 128K: Map RAM bank 4 to $C000; Map normal screen; Map ROM 0
F348 LD BC,$7FFD
F34B OUT (C),A
F34D LD C,$FD
F34F LD HL,$FFBF
F352 LD D,$08
F354 EXX
F355 EX AF,AF' Unbank input index
F356 ADD A,A HL = $F32A + A*4 -- i.e. it's 1-indexed speech_samples_table
F357 ADD A,A
F358 LD HL,$811E
F35B LD C,A
F35C LD B,$00
F35E ADD HL,BC
F35F LD E,(HL) DE = wordat(HL); HL += 2 -- read length
F360 INC HL
F361 LD D,(HL)
F362 INC HL
F363 LD A,(HL) HL = wordat(HL) -- read address
F364 INC HL
F365 LD H,(HL)
F366 LD L,A
plsp_f367_128k F367 LD C,$02 C = 2 -- iterations (two nibbles)
F369 LD A,(HL) A = *HL -- read a sample (or two?)
F36A RRA A = A ROR 4
F36B RRA
F36C RRA
F36D RRA
plsp_f36e_loop F36E AND $0F A &= 15
F370 EX AF,AF'
F371 EXX
F372 LD B,H B = H which is $FF
F373 LD A,D A = D which is 8 -- register 8: Channel A volume
F374 OUT (C),A C is $FD
F376 LD B,L B = L which is $BF
F377 EX AF,AF' A = value loaded above
F378 OUT (C),A Write to register
F37A EX AF,AF' Bank it again
F37B INC A 8 -> 9 -- register 9: Channel B volume
F37C LD B,H B = $FF
F37D OUT (C),A C is $FD
F37F LD B,L B = L which is $BF
F380 EX AF,AF' A = value loaded above
F381 OUT (C),A Write to register
F383 EX AF,AF' Bank it again
F384 INC A 9 -> 10 -- register 9: Channel C volume
F385 LD B,H B = $FF
F386 OUT (C),A C is $FD
F388 LD B,L B = L which is $BF
F389 EX AF,AF' A = value loaded above
F38A OUT (C),A Write to register
F38C EXX
F38D LD B,$13 Delay loop (lower value => higher frequency)
page_in_stage_128k_2 F38F DJNZ page_in_stage_128k_2
F391 LD A,(HL) Load next nibble (same byte, but next nibble)
F392 DEC C Decrement nibble counter
F393 JR NZ,plsp_f36e_loop Loop plsp_f36e_loop
F395 INC HL Advance to next byte of sample data
F396 DEC DE Decrement sample data counter
F397 LD A,D Loop to plsp_f367_128k while sample data remains
F398 OR E
F399 JP NZ,$815B
F39C JP $8208 Exit via relocated reset_paging_128k
plsp_f39f_128k F39F LD A,($8E4A) -- frame delay?
F3A2 CP $2A Return if A < 42
F3A4 RET C
F3A5 CALL silence_audio_hook Call silence_audio_hook
F3A8 XOR A var_a239 = 0
F3A9 LD ($A239),A
F3AC INC A A = 1
F3AD LD ($A23A),A Load var_a23a -- copy of noise pitch
F3B0 LD ($8E4A),A Self modify 8E49
F3B3 LD HL,$C006
plsp_f3b6_128k F3B6 LD ($81C6),HL Self modify 'CALL xxxx' @ $81C5 ($F3D1 before relocation - below)
F3B9 LD HL,$B000 Copy 4096 bytes from $B000 to $F000 (preserving registers for later)
F3BC LD DE,$F000
F3BF LD BC,$1000
F3C2 PUSH HL
F3C3 PUSH DE
F3C4 PUSH BC
F3C5 LDIR
F3C7 LD ($81CE),SP Self modify 'LD SP,xxxx' @ 81CD ($F3D9 here - below)
F3CB LD SP,$A214 new sp
F3CE CALL $81D6 Call relocated f3e2_128k
F3D1 CALL $0000 Self modified by plsp_f3b6_128k
F3D4 PUSH AF Preserve ?
F3D5 CALL $81D6 Call relocated f3e2_128k
F3D8 POP AF Restore ?
F3D9 LD SP,$0000 Restore SP - self modified by F3C7 above
F3DC POP BC Copy 4096 bytes from $B000 to $F000
F3DD POP HL
F3DE POP DE
F3DF LDIR Copy
F3E1 RET Return
f3e2_128k F3E2 LD HL,$C000 HL = $C000
F3E5 LD B,$04 4 iterations
F3E7 LD E,L E = 0
f3e8_loop F3E8 PUSH BC Preserve iterations
F3E9 LD D,$B0 DE = $B000
F3EB LD BC,$1000 4096 bytes
F3EE PUSH BC Preserve
F3EF PUSH HL
F3F0 LDIR Copy
F3F2 LD A,$03 A = 3
F3F4 CALL engine_sfx_setup_0 Jump into engine_sfx_setup with engine speed setup
F3F7 POP HL Retrieve from stack
F3F8 POP BC
F3F9 PUSH BC
F3FA PUSH HL
F3FB LD D,$B0 DE = $B000
f3fd_loop F3FD LD A,(DE) A = *DE
F3FE LDI Transfer a byte
F400 DEC HL HL[-1] = A
F401 LD (HL),A
F402 INC HL
F403 JP PE,$81F1 Loop if (parity even) to f3fd_loop
F406 CALL $8208 Call relocated reset_paging_128k
F409 POP DE Restore
F40A POP BC
F40B LD H,$B0 HL = $B000
F40D LDIR Copy
F40F LD H,D H = D
F410 POP BC Restore iterations
F411 DJNZ f3e8_loop Loop to f3e8_loop
F413 RET Return
reset_paging_128k F414 XOR A 128K: Set paging register to default
F415 LD BC,$7FFD
F418 OUT (C),A
F41A RET Return
attract_mode_hook_128k F41B LD HL,$C000 HL = $C000
page_in_stage_128k_3 F41E CALL $81AA Call relocated plsp_f3b6_128k (speech)
F421 AND A Return if A is zero
F422 RET Z
F423 LD HL,$5D2B HL -> attract_data
F426 CALL setup_game Call setup_game
F429 LD A,$02 var or self modify or ..?
F42B LD ($825E),A
F42E LD HL,$0190 Set speed to $190
F431 LD ($A24A),HL
f434_128k_loop F434 CALL cpu_driver Call cpu_driver
F437 LD A,($8001) Load attract_cycle
F43A AND A Set flags
F43B LD DE,$8296 -> enter_for_options_messages
F43E JR Z,f44b_key_check Jump to f44b_key_check
F440 CALL keyscan Call keyscan
F443 AND $10 Was FIRE pressed?
F445 JP NZ,play_start_noise Jump to play_start_noise if so
F448 LD DE,$8285 -> press_gear_messages
f44b_key_check F44B LD A,$BF Read port $BFFE -- ENTER, L, K, J, H
F44D IN A,($FE)
F44F CPL Complement the value returned to change it from to active-high
F450 RRA ?Shift out lsb
F451 LD HL,$C009
F454 JR C,page_in_stage_128k_3 ?Jump if ENTER was pressed
F456 EX DE,HL
F457 LD A,$F0
F459 RRCA -- why load A then shift? self modified?
F45A LD ($824C),A
F45D JR NC,page_in_stage_128k_4
F45F LD A,(HL)
F460 CALL print_message Call print_message
page_in_stage_128k_4 F463 LD A,($A231) If transition_control != 0 jump
F466 AND A
F467 JR NZ,f488_128k
F469 LD A,$00 -- smells like self modified
F46B AND A
F46C JP M,$820F
F46F DEC A A--
F470 LD ($825E),A self modifying?
F473 JP P,attract_mode_1
F476 LD A,$08 Transition type?
F478 CALL setup_transition Call setup_transition
F47B JR f488_128k
f47d_128k F47D LD HL,$82AD -- must be messages ptr below ($8208+165 means ?)
F480 JR NZ,f485_128k
F482 LD HL,$830F -- must be messages ptr below ($8208+263 means ?)
f485_128k F485 CALL message_printing_related Call message_printing_related
f488_128k F488 CALL transition Call transition
F48B CALL draw_screen Call draw_screen
F48E JP $8228 Loop to f434_128k_loop
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