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vars.asm
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vars.asm
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; /////////////////////////////////////////////////////////////////////////////
; Znake (ZX Spectrum 48K)
; -----------------------------------------------------------------------------
; vars.asm
; -----------------------------------------------------------------------------
; Copyright (C) 2016, Chris Wyatt
; All rights reserved
; Distributed under the Apache 2 license (see LICENSE)
; /////////////////////////////////////////////////////////////////////////////
menu_last_direction: db 0x00
menu_last_direction_frame_count: db 0x00
str_title: db "Z N A K E\0"
str_keyboard: db "K - Keyboard\0"
str_kempston: db "J - Kempston\0"
str_credits: db "Chris Wyatt ", 0x7f, " 2016, 2017\0"
str_easy: db " Easy \0"
str_normal: db "Normal\0"
str_hard: db " Hard \0"
str_expert: db "Expert\0"
str_guru: db " Guru \0"
str_score_lbl: db "Sc:\0"
str_hi_score_lbl: db "Hi:\0"
difficulty: db 0x01
; string, display location, snake speed, high score
difficulties:
dw str_easy
dw 0x0d07
db 18
dw 0x0000
dw str_normal
dw 0x0d09
db 6
dw 0x0000
dw str_hard
dw 0x0d0b
db 4
dw 0x0000
dw str_expert
dw 0x0d0d
db 3
dw 0x0000
dw str_guru
dw 0x0d0f
db 2
dw 0x0000
; Starting offset for snake history
snake_history_tail_offset: db 0x00
; End offset for snake history
snake_history_head_offset: db 0x00
; The length of the clean snake history table (byte per item)
snake_history_clean_length: db 0x00
; The length of both free squares tables (byte per item)
free_squares_bl_length: db 0x00
free_squares_br_length: db 0x00
free_squares_tr_length: db 0x00
free_squares_tl_length: db 0x00
; Low byte of current free squares table
free_squares_low: db 0x00
; Pointer to current free squares table length
free_squares_length_pointer: dw 0x0000
; Current direction of snake (bits: 0000UDLR)
snake_direction_current: db 0x00
; Snake direction queue (bits: UDLRUDLR)
; (low bits have higher priority)
snake_direction_queue: db 0x00
; The last processed Kempston input
last_input: db 0x00
; The last direction pushed to the queue
last_direction: db 0x00
; The current location of the snake's food
current_food_location: db 0x00
; Bit 0: Food eaten
; Bit 1: Kempston enabled
; Bit 2: Reserved
; Bit 3: Reserved
; Bit 4: Invalidate BL free squares table
; Bit 5: Invalidate BR free squares table
; Bit 6: Invalidate TR free squares table
; Bit 7: Invalidate TL free squares table
flags: db 0x00
previous_frame_count: db 0x00
; i.e. snake speed (higher = slower)
no_of_frames_per_update: db 0x00
; Calculating this from snake history would be too expensive
snake_length: db 0
seed: defw 0x0000
; BCD
score: dw 0x0000
str_score db " \0"
; BCD
hi_score: dw 0x0000
str_hi_score db "0000\0"