332 lines
12 KiB
Z80 Assembly
332 lines
12 KiB
Z80 Assembly
org 100h
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siob_data equ 083h
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siob_ctrl equ 082h
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lcd_data equ 0dbh
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lcd_ctrl equ 0dah
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celcius_offset equ 08ah
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pressure_offset equ 0cah
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humid_offset equ 09eh
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spinner_offset equ 0e7h ; line 4, column 20 on a 20x4 panel
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bs_char equ 01h ; cgram slot holding our backslash
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bs_cgram equ 048h ; set cgram address, slot 1 row 0
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bdos equ 0005h
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conout equ 02h
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conin equ 01h
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dconio equ 06h
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printstr equ 09h
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start:
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ld c,printstr ; tell the operator how to quit
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ld de,quitmsg
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call bdos
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call init_lcd
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call init_siob
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call lcd_delay
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call load_glyphs
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ld a,celcius_offset ; write celcius label
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out (lcd_ctrl),a
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call lcd_delay
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ld hl,clabel
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call print_str_to_lcd
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ld a,pressure_offset ; write pressure label
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out (lcd_ctrl),a
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call lcd_delay
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ld hl,plabel
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call print_str_to_lcd
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ld a,humid_offset ; write humidity label
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out (lcd_ctrl),a
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call lcd_delay
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ld hl,hlabel
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call print_str_to_lcd
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main:
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call read_char_b ; never blocks now
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jr nc,check_quit ; wire is idle, go look at the keyboard
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ld hl,rx_seen
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ld (hl),0ffh ; note traffic, a holds the char untouched
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call parse_char
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jr main ; drain the sio while it still has data
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check_quit:
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call spin_tick ; keep the spinner turning while idle
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ld c,dconio ; direct console i/o, no echo
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ld e,0ffh ; ff polls, returning zero if no key
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call bdos
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cp a,051h ; Q
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ret z
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cp a,071h ; q
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ret z
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jr main ; no key, or a key we ignore
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init_siob:
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ld a,018h ; channel reset
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out (siob_ctrl),a
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ld a,04h
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out (siob_ctrl),a ; wr4 baud settings
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ld a,0c4h
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out (siob_ctrl),a
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ld a,03h
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out (siob_ctrl),a ; rx enable
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ld a,0c1h
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out (siob_ctrl),a
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ld a,05h
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out (siob_ctrl),a ; tx settings
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ld a,0eah
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out (siob_ctrl),a
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ret
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init_lcd:
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ld a,38h
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out (lcd_ctrl),a ; function 8 bit, 2 lines, 5x8 dot font
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call lcd_delay
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ld a,0ch
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out (lcd_ctrl),a ; display on, cursor off, no blink
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call lcd_delay
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ld a,01h
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out (lcd_ctrl),a ; clear display
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ret
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load_glyphs: ; the a00 rom has yen at 5ch, so draw our own backslash
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ld a,bs_cgram
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out (lcd_ctrl),a
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call lcd_delay
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ld hl,glyph_bs
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ld e,08h ; eight rows, and e survives lcd_delay
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glyph_row:
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ld a,(hl)
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out (lcd_data),a ; cgram address auto increments
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call lcd_delay
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inc hl
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dec e
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jr nz,glyph_row
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ret
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lcd_delay:
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ld bc,500
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delay1:
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dec bc
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ld a,b
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or c
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jr nz,delay1
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ret
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convert_to_hpa: ; shift the decimal point in (pressure) two places left
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ld hl,pressure
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ld b,0 ; count of digits ahead of the point
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find_point:
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ld a,(hl)
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or a
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ret z ; no point in the string, leave it alone
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cp a,2eh ; period
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jr z,found_point
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inc hl
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inc b
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jr find_point
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found_point:
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ld a,b
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cp 3 ; need three whole digits to shift by two
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ret c
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dec hl ; step back over the ones digit
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dec hl ; hl now holds the new tenths digit
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ld a,(hl)
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ld (hl),2eh ; drop the point in two places left
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inc hl
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ld (hl),a ; and the saved digit after it
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inc hl
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ld (hl),00h ; null terminate, discarding the rest
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ret
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read_char_b: ; carry set with the char in a, carry clear if nothing waiting
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in a,(siob_ctrl)
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bit 0,a
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jr z,no_char
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in a,(siob_data)
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scf ; flag a as a real character
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ret
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no_char:
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or a ; clears carry, a holds status not data
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ret
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parse_char: ; char should be in register a
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cp a,25h ; percent sign (end of transmission)
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jr z,print_telem_to_lcd
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cp a,0dh ; carriage return
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jr z,null_term
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cp a,0ah ; new line
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jr z,parse_char_done
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cp a,054h ; T character
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jr z,set_char_idx_t ; point the char_idx to the temperature buffer
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cp a,050h ; P character
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jr z,set_char_idx_p ; point the char_idx to the pressure buffer
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cp a,048h ; H character
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jr z,set_char_idx_h ; point the char_idx to the humidity buffer
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push af
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ld a,(char_cnt) ; get number stored in char_cnt
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cp char_max ; compare it to maximum character count
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jr nc,store_full ; if no carry, the buffer is full
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inc a ; otherwise increment
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ld (char_cnt),a ; and store back in char_cnt
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pop af
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ld bc,(char_idx) ; get address stored in char_idx
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ld (bc),a ; deref that address and store char
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inc bc
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ld (char_idx),bc ; store incremented address in char_idx
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parse_char_done:
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ret
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store_full:
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pop af
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ret
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print_telem_to_lcd:
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call move_to_tempaddr
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ld hl,temperature
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call print_str_to_lcd
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call convert_to_hpa
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call move_to_presaddr
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ld hl,pressure
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call print_str_to_lcd
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call move_to_humidaddr
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ld hl,humidity
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call print_str_to_lcd
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ld a,1h
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ret
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null_term: ; null terminate end of parsed string in memory
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ld a,00h
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ld bc,(char_idx)
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ld (bc),a
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jr parse_char_done
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set_char_idx_t:
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ld bc,temperature
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ld (char_idx),bc
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xor a ; reset char_cnt to zero
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ld (char_cnt),a
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ret
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set_char_idx_p:
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ld bc,pressure
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ld (char_idx),bc
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xor a ; reset char_cnt to zero
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ld (char_cnt),a
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ret
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set_char_idx_h:
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ld bc,humidity
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ld (char_idx),bc
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xor a ; reset char_cnt to zero
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ld (char_cnt),a
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ret
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print_str_to_lcd: ; place memory address in hl first
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ld a,(hl)
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or a
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jr z,print_done
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out (lcd_data),a
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call lcd_delay
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inc hl
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jr print_str_to_lcd
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print_done:
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ret
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spin_tick: ; count down, then step the spinner one frame
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ld hl,(spin_cnt)
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dec hl
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ld (spin_cnt),hl
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ld a,h ; dec hl leaves the flags alone
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or l
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ret nz ; not time yet
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ld hl,spin_ticks ; reload, so the interval stays regular
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ld (spin_cnt),hl
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ld a,(rx_seen) ; did anything arrive this interval?
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or a
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ret z ; no, hold the frame and stop spinning
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xor a
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ld (rx_seen),a ; clear it for the next interval
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ld a,(spin_idx)
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inc a
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and 03h ; four frames, then wrap
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ld (spin_idx),a
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ld hl,spinner
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ld d,00h
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ld e,a
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add hl,de ; hl now points at the frame character
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ld a,spinner_offset
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out (lcd_ctrl),a ; park the cursor bottom right
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call lcd_delay
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ld a,(hl) ; fetch late, lcd_delay wrecks a and bc but not hl
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out (lcd_data),a
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call lcd_delay
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ret
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move_to_tempaddr:
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ld a,85h
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out (lcd_ctrl),a
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call lcd_delay
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ret
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move_to_presaddr:
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ld a,0c3h
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out (lcd_ctrl),a
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call lcd_delay
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ret
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move_to_humidaddr:
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ld a,99h
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out (lcd_ctrl),a
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call lcd_delay
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ret
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clabel: DB 'degree C',0
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plabel: DB 'hPa',0
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hlabel: DB '% RH',0
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quitmsg: DB 'Press Q to quit',0dh,0ah,'$'
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spinner: DB '-','/','|',bs_char
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glyph_bs: DB 00h,10h,08h,04h,02h,01h,00h,00h
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spin_ticks equ 3000 ; idle polls per frame, tune on real hardware
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spin_idx DB 03h ; wraps to the first frame on the next tick
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spin_cnt DW spin_ticks
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rx_seen DB 00h ; set on every byte off the sio
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char_max equ 15
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char_cnt DB 0
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char_idx DW scratch
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scratch: DS 16
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temperature: DS 16
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humidity: DS 16
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pressure: DS 16
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