cv2ins_sample_before

function DeletePlayer2Input()
{
  global $linker,$space;
  // Frees RAM addresses F4,F6 (new buttons player2),
  //                     F2,F8 (current buttons player2)
  /* Change NMI_UpdateInput (C453-C4AE, 92 bytes) to to:
   *          ldx #1                    ;2
   *          jsr @read                 ;12+189
   *          dex                   ;2
   *          jsr @read                 ;12+189
   *          lda $00                   ;3
   *          cmp $01                   ;3
   *          bne @blank (+14)              ;2
   *          tay                   ;2
   *          eor $F1 (Input_CurrentJoyButtonsOrig) ;3
   *          and $00                   ;3
   *          sta $F5 (Input_NewJoyButtonsWork)     ;3
   *          sta $F3 (Input_NewJoyButtonsOrig)     ;3
   *          sty $F7 (Input_CurrentJoyButtonsWork) ;3
   *          sty $F1 (Input_CurrentJoyButtonsOrig) ;3
   *          rts
   *    @blank:
   *          stx $F5                   ;3
   *          stx $F3                   ;3
   *          nop;nop;nop;php;plp                       ;13
   *          rts
   *    @read:
   *          ldy #1        ;2
   *          sty $4016     ;4
   *          dey       ;2
   *          sty $4016     ;4
   *          ldy #8        ;2
   *    @loop:
   *          lda $4016     ;4
   *          sta $04       ;3
   *          lsr a     ;2
   *          ora $04       ;3
   *          lsr a     ;2
   *          rol $00,x     ;3
   *          dey       ;2
   *          bne @loop     ;3
   *                    ;  (4+3+2+3+2+3+2+3)*8-1 = 175
   *          rts       ; @read cost: 189 cycles + JSR+RTS
   *
   * Cost (normally):     2+12+189+2+12+189+3+3+2+2+6*3 = 434 cycles
   * Cost (if DMA error): 2+12+189+2+12+189+3+3+3+6+13  = 434 cycles
   */
  $location = 0x1C453;
  $space[$location] = 0x1C4AF - 0x1C453;
  $b = new Blob("NMI_UpdateInput",
             "\xA2\x01");
  $b->AppendCallPointerTo("NMI_ReadOneJoypad");
  $b->AppendRawData(
             "\xCA");
  $b->AppendCallPointerTo("NMI_ReadOneJoypad");
  $b->AppendRawData(
             "\xA5\x00\xC5\x01\xD0\x0E".
             "\xA8\x45\xF1\x25\x00\x85\xF5\x85\xF3\x84\xF7\x84\xF1\x60".
             "\x86\xF5\x86\xF3\xEA\xEA\xEA\x08\x28\x60");
  $b->AddPublicHere("NMI_ReadOneJoypad");
  $b->AppendRawData(
             "\xA0\x01\x8C\x16\x40\x88\x8C\x16\x40".
             "\xA0\x08".
             "\xAD\x16\x40\x85\x04\x4A\x05\x04\x4A\x36\x00".
             "\x88\xD0\xF2".
             "\x60");
  $linker->AddBlobTakeSpace($space, $b, $location);

  /* Change _func_1C5EF, which clears memory from 300..3C5,
   * to a more optimal implementation:
   *        ldy #$C6
   *        lda #0
   * @loop: dey
   *        sta $0300,y
   *        bne @loop
   *        rts
   * (Also erases a couple of unused functions)
   */
  $location = 0x1C5EF;
  $space[$location] = 0xC615-0xC5EF;
  $b = new Blob("ReplaceC5EF",
      "\xA0\xC6\xA9\x00".
      "\x88\x99\x00\x03".
      "\xD0\xFA\x60");
  $linker->AddBlobTakeSpace($space, $b, $location);
}