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The stereo opcode variants have bit 1 of the command stream set. The polyphony is split into two parts: 1) polyphony, meaning that voices reuse the same opcodes; 2) multitrack voices, meaning that a track triggers more than voice. They both can be flexible defined in any combinations: for example voice 1 and 2 can be triggered by track 1 and use instrument 1, and voice 3 by track 2/instrument 2 and voice 4 by track 3/instrument 2. This is achieved through the use of bitmasks: in the aforementioned example, bit 1 of su_voicetrack_bitmask would be set, meaning "the voice after voice #1 will be triggered by the same track". On the other hand, bits 1 and 3 of su_polyphony_bitmask would be set to indicate that "the voices after #1 and #3 will reuse the same instruments".
63 lines
2.8 KiB
NASM
63 lines
2.8 KiB
NASM
;-------------------------------------------------------------------------------
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; su_op_advance function: opcode to advance from one instrument to next
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;-------------------------------------------------------------------------------
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; Stack: voice wrkptr valptr comptr
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; voice : the number of voice we are currently processing
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; wrkptr : pointer to the first unit of current voice - su_unit.size
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; valptr : pointer to the first unit's value of current voice
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; comptr : pointer to the first command of current voice
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; COM : pointer to the command after current command
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; Output: WRK : pointer to the next unit to be processed
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; VAL : pointer to the values of the next to be processed
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; COM : pointer to the next command to be executed
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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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SECT_TEXT(suopadvn)
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%ifdef INCLUDE_POLYPHONY
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EXPORT MANGLE_FUNC(su_op_advance,0) ; Stack: addr voice wrkptr valptr comptr
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mov WRK, dword [esp+8] ; WRK = wrkptr
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add WRK, su_voice.size ; move to next voice
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mov dword [esp+8], WRK ; update stack
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mov ecx, dword [esp+4] ; ecx = voice
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bt dword [su_polyphony_bitmask],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, dword [esp+12] ; rollback to where we were earlier
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mov COM, dword [esp+16]
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jmp short su_op_advance_finish
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su_op_advance_next_instrument:
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mov dword [esp+12], VAL ; save current VAL as a checkpoint
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mov dword [esp+16], COM ; save current COM as a checkpoint
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su_op_advance_finish:
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inc ecx ; voice++
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mov dword [esp+4], ecx
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ret
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%else
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EXPORT MANGLE_FUNC(su_op_advance,0) ; Stack: addr voice wrkptr valptr comptr
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mov WRK, dword [esp+8] ; WRK = wrkptr
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add WRK, su_voice.size ; move to next voice
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mov dword [esp+8], WRK ; update stack
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inc dword [esp+4] ; voice++
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ret
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%endif
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;-------------------------------------------------------------------------------
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; Constants
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;-------------------------------------------------------------------------------
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%ifdef SU_USE_DLL_DC_FILTER
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%ifndef C_DC_CONST
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SECT_DATA(suconst)
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c_dc_const dd 0.99609375 ; R = 1 - (pi*2 * frequency /samplerate)
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%define C_DC_CONST
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%endif
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%endif |