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gbdk-2020

GameBoy Development Kit
download: https://git.y1.nz/archives/gbdk.tar.gz
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gbdk-lib/libc/targets/mos6502/mode.s

      1     .include    "global.s"
      2 
      3     .title  "screen modes"
      4     .module Modes
      5 
      6     .area   GBDKOVR (PAG, OVR)
      7     temp_word:                  .ds 2
      8 
      9     ;; BANKED:  checked
     10     .area   _HOME
     11 
     12 _mode::
     13 .set_mode::
     14     sta .mode
     15     ;; AND to get rid of the extra flags
     16     and #0x03
     17     asl                     ; Multiply mode by 4
     18     asl
     19     clc
     20     adc #<.MODE_TABLE
     21     sta temp_word
     22     lda #0
     23     adc #>.MODE_TABLE
     24     sta temp_word+1
     25     jmp [*temp_word]        ; Jump to initialization routine
     26 
     27 _get_mode::
     28     lda .mode
     29     rts

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