Mercurial > vba-clojure

     1 

     2 (defn count-frames* []

     3   (-> (tick (mid-game))

     4       (IE! 0) ; disable interrupts

     5       (inject-item-assembly

     6        ;; write 00010000 to 0xFF00 to select joypad

     7        [0x18   ;D31D                    ; jump over          

     8         0x02   ;D31E                    ; the next 2 bytes

     9         0x00   ;D31F                    ; frame-count

    10         0x00   ;D320                    ; v-blank-prev

    11 

    12         

    13         0xFA   ;D321

    14         0x41   ;D322                    ; load (FF41) into A

    15         0xFF   ;D323                    ; this contains mode flags

    16 

    17         0x47   ;; copy A -> B

    18         

    19         0xCB

    20         0x3F ;; shift A right

    21         0x2F ;; complement A

    22 

    23         0xA0 ;; A & B -> A.

    24         0x47 ;; copy A -> B. Now the first bit of B is (VB == 1)

    25         

    26         0xFA

    27         0x20

    28         0xD3 ;; load v-blank-prev into A

    29 

    30         0xA0 ;; A & B -> A. 

    31         0x4F ;; copy A to C. Now C contains increment-counter?

    32 

    33         0xFA

    34         0x1F

    35         0xD3 ;; load frame-count into A

    36 

    37         0x81 ;; add increment-counter? to frame-count

    38         0xEA ;; store A into frame-count

    39         0x1F

    40         0xD3

    41 

    42         0x3E ;; load 1 into A

    43         0x01

    44         0xA0 ;; A & B -> A. Now A is (VB==1)

    45         0xEA ;; store A into v-blank-prev

    46         0x20

    47         0xD3

    48 

    49         0xC3   ;D348                   ; return to beginning

    50         0x1D   ;D349

    51         0xD3   ;D34A

    52 

    53 

    54         ])))
author	Robert McIntyre <rlm@mit.edu>
date	Fri, 16 Mar 2012 20:55:28 -0500
parents	bcb5c41626b4
children