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https://github.com/vsariola/sointu.git
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66 lines
3.2 KiB
PHP
66 lines
3.2 KiB
PHP
;-------------------------------------------------------------------------------
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; ADVANCE opcode: advances from one voice to next
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;-------------------------------------------------------------------------------
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; Checks if this was the last voice of current instrument. If so, moves to
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; next opcodes and updates the stack to reflect the instrument change.
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; If this instrument has more voices to process, rolls back the COM and VAL
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; pointers to where they were when this instrument started.
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;
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; There is no stereo version.
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;-------------------------------------------------------------------------------
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SECT_TEXT(suopadvn)
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EXPORT MANGLE_FUNC(su_op_advance,0)
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%ifdef INCLUDE_POLYPHONY
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mov WRK, [_SP+su_stack.wrk] ; WRK points to start of current voice
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add WRK, su_voice.size ; move to next voice
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mov [_SP+su_stack.wrk], WRK ; update the pointer in the stack to point to the new voice
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mov ecx, [_SP+su_stack.voiceno] ; ecx = how many voices remain to process
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dec ecx ; decrement number of voices to process
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bt dword [_SP+su_stack.polyphony], ecx ; if voice bit of su_polyphonism not set
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jnc su_op_advance_next_instrument ; goto next_instrument
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mov VAL, PTRWORD [_SP+su_stack.val] ; if it was set, then repeat the opcodes for the current voice
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mov COM, PTRWORD [_SP+su_stack.com]
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su_op_advance_next_instrument:
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mov PTRWORD [_SP+su_stack.val], VAL ; save current VAL as a checkpoint
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mov PTRWORD [_SP+su_stack.com], COM ; save current COM as a checkpoint
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su_op_advance_finish:
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mov [_SP+su_stack.voiceno], ecx
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ret
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%else
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mov WRK, PTRWORD [_SP+su_stack.wrk] ; WRK = wrkptr
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add WRK, su_voice.size ; move to next voice
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mov PTRWORD [_SP+su_stack.wrk], WRK ; update stack
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dec PTRWORD [_SP+su_stack.voiceno] ; voices--
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ret
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%endif
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;-------------------------------------------------------------------------------
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; SPEED opcode: modulate the speed (bpm) of the song based on ST0
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;-------------------------------------------------------------------------------
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; Mono: adds or subtracts the ticks, a value of 0.5 is neutral & will7
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; result in no speed change.
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; There is no STEREO version.
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;-------------------------------------------------------------------------------
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%if SPEED_ID > -1
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SECT_TEXT(suspeed)
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EXPORT MANGLE_FUNC(su_op_speed,0)
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do fmul dword [,c_bpmscale,] ; (2*s-1)*64/24, let's call this p from now on
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call MANGLE_FUNC(su_power,0) ; 2^p, this is how many ticks we should be taking
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fld1 ; 1 2^p
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fsubp st1, st0 ; 2^p-1, the player is advancing 1 tick by its own
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fadd dword [WRK+su_speed_wrk.remainder] ; t+2^p-1, t is the remainder from previous rounds as ticks have to be rounded to 1
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push _AX
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fist dword [_SP] ; Main stack: k=int(t+2^p-1)
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fisub dword [_SP] ; t+2^p-1-k, the remainder
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pop _AX
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add dword [_SP+su_stack.rowtick], eax ; add the whole ticks to row tick count
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fstp dword [WRK+su_speed_wrk.remainder] ; save the remainder for future
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ret
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%define USE_C_BPMSCALE
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%endif
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