Add activity spinner

bme280_util.z80

@@ -9,6 +9,10 @@ lcd_ctrl        equ     0dah
 celcius_offset  equ     08ah
 pressure_offset equ     0cah
 humid_offset    equ     09eh
+spinner_offset  equ     0e7h                    ; line 4, column 20 on a 20x4 panel
+
+bs_char         equ     01h                     ; cgram slot holding our backslash
+bs_cgram        equ     048h                    ; set cgram address, slot 1 row 0
 
 bdos            equ     0005h
 conout          equ     02h
@@ -26,6 +30,8 @@ start:
                 call    init_siob
                 call    lcd_delay
 
+                call    load_glyphs
+
                 ld      a,celcius_offset        ; write celcius label
                 out     (lcd_ctrl),a
                 call    lcd_delay
@@ -47,10 +53,13 @@ start:
 main:
                 call    read_char_b             ; never blocks now
                 jr      nc,check_quit           ; wire is idle, go look at the keyboard
+                ld      hl,rx_seen
+                ld      (hl),0ffh               ; note traffic, a holds the char untouched
                 call    parse_char
                 jr      main                    ; drain the sio while it still has data
 
 check_quit:
+                call    spin_tick               ; keep the spinner turning while idle
                 ld      c,dconio                ; direct console i/o, no echo
                 ld      e,0ffh                  ; ff polls, returning zero if no key
                 call    bdos
@@ -93,6 +102,21 @@ init_lcd:
 
                 ret
 
+load_glyphs:                                    ; the a00 rom has yen at 5ch, so draw our own backslash
+                ld      a,bs_cgram
+                out     (lcd_ctrl),a
+                call    lcd_delay
+                ld      hl,glyph_bs
+                ld      e,08h                   ; eight rows, and e survives lcd_delay
+glyph_row:
+                ld      a,(hl)
+                out     (lcd_data),a            ; cgram address auto increments
+                call    lcd_delay
+                inc     hl
+                dec     e
+                jr      nz,glyph_row
+                ret
+
 lcd_delay:
                 ld      bc,500
 delay1:
@@ -230,11 +254,44 @@ print_str_to_lcd:                                 ; place memory address in hl f
 print_done:
                 ret
 
+spin_tick:                                      ; count down, then step the spinner one frame
+                ld      hl,(spin_cnt)
+                dec     hl
+                ld      (spin_cnt),hl
+                ld      a,h                     ; dec hl leaves the flags alone
+                or      l
+                ret     nz                      ; not time yet
+
+                ld      hl,spin_ticks           ; reload, so the interval stays regular
+                ld      (spin_cnt),hl
+
+                ld      a,(rx_seen)             ; did anything arrive this interval?
+                or      a
+                ret     z                       ; no, hold the frame and stop spinning
+                xor     a
+                ld      (rx_seen),a             ; clear it for the next interval
+
+                ld      a,(spin_idx)
+                inc     a
+                and     03h                     ; four frames, then wrap
+                ld      (spin_idx),a
+
+                ld      hl,spinner
+                ld      d,00h
+                ld      e,a
+                add     hl,de                   ; hl now points at the frame character
+
+                ld      a,spinner_offset
+                out     (lcd_ctrl),a            ; park the cursor bottom right
+                call    lcd_delay
+                ld      a,(hl)                  ; fetch late, lcd_delay wrecks a and bc but not hl
+                out     (lcd_data),a
+                call    lcd_delay
+                ret
+
 move_to_tempaddr:
-                ld      c,a
                 ld      a,85h
                 out     (lcd_ctrl),a
-                ld      a,c
                 call    lcd_delay
                 ret
 
@@ -256,6 +313,13 @@ hlabel:         DB      '% RH',0
 
 quitmsg:        DB      'Press Q to quit',0dh,0ah,'$'
 
+spinner:        DB      '-','/','|',bs_char
+glyph_bs:       DB      00h,10h,08h,04h,02h,01h,00h,00h
+spin_ticks      equ     3000                    ; idle polls per frame, tune on real hardware
+spin_idx        DB      03h                     ; wraps to the first frame on the next tick
+spin_cnt        DW      spin_ticks
+rx_seen         DB      00h                     ; set on every byte off the sio
+
 char_max        equ     15
 char_cnt        DB      0