import: untested anim decoder

asm/play.s

@@ -0,0 +1,132 @@
+//
+// New Animated File Format
+//
+
+// xxx_xxxx_xxxx_xxx is the number of bytes 1-16384 to follow (0 == 1 byte)
+
+%0xxx_xxxx_xxxx_xxx1 - Copy Bytes - straight copy bytes
+%1xxx_xxxx_xxxx_xxx1 - Skip Bytes - skip bytes / move the cursor
+%1xxx_xxxx_xxxx_xxx0 - Dictionary Copy Bytes from  frame buffer to frame buffer
+
+%0000_0000_0000_0000- Source Skip -> Source pointer skips to next bank of data
+%0000_0000_0000_0010- End of Frame - end of frame
+%0000_0000_0000_0110- End of Animation / End of File / no more frames
+
+// other remaining codes, are reserved for future expansion
+
+
+16 bit opcode
+
+%1 xxx xxxx xxxx xxx 0
+%0 xxx xxxx xxxx xxx 0
+
+// X = SRC
+// Y = DST
+
+// Source Data Stream Copy
+// Dictionary Copy
+// xx xxxx xxxx xxxx // up to 16384 length of copy (0 is a copy length of 1 byte, so it's length-1)
+
+// Copy this code to your direct page, please make sure it's aligned to a page
+// The buffer is hardcoded to be at $012000, to take advantage of fast reads
+
+// pass in a pointer to the start of the compressed stream
+// ldx #offset in source bank
+// lda #source bank
+// we assume all next bank data is sequential from this first bank, but it
+// wouldn't be hard to work from a list of banks, to make the player more
+// friendly
+
+//---  this code sits at location $0 in the DP register
+//---  DP may be anywhere in bank 0, but make sure it's PAGE aligned
+//---- for performance reasons
+
+        org $0
+        mx %00
+        phb
+        sep #$30
+        sta <srcbank+1           // self modify the code for mvn
+        sta <read_opcode+3       // data stream reader
+        sta <dictionary_offset+3 // opcode stream reader
+        rep #$31
+        ldy #$2000              // it's a new frame, cursor starts at beginning of SHR
+
+        bra     read_opcode
+
+extended_command
+
+        lsr
+        bcs :not end of frame
+
+        ldy #$2000
+        // check elapsed ticks (need at least 1)
+
+        // For now just inline vsync (preferable to check the number of
+        // if jiffy that have elapsed, because if the animation uses more than
+        // roughly 10% of the screen we don't want to sync here
+
+
+        bra read_opcode
+
+:end_of_file
+        plb    // restore bank
+        rtl
+
+:not_end_of_frame
+        beq :end_of_file
+
+        cmp #1
+        bne :not_new_bank
+
+        // source data, new bank
+        inc <read_opcode+3        // 6
+        inc <dictionary_offset+3  // 6
+
+        // start of new bank
+        ldx #0
+
+:not_new_bank
+       
+        ; currently reserved
+        bra read_opcode
+
+stream_copy:
+        inx
+        inx
+        lsr
+        bcc extended_command
+srcbank:
+        mvn ss,dd
+read_opcode:
+        ldal opcode,x
+        bpl stream_copy
+        inx
+        inx
+dictionary_copy:
+        and #$7FFF
+        lsr
+        bcs cursor_skip
+
+        sta <temp
+
+        stx <dictionary_offset+1
+dictionary_offset
+        ldal dictionary_offset
+        tax
+
+        lda <temp
+        // dictionary copy
+        mvn dd,dd
+
+        ldx <dictionary_ofset+1
+        inx
+        inx
+
+        bra read_opcode
+
+cursor_skip
+        sty temp
+        adc temp
+        tay
+        bra read_opcode
+