JP2576614B2 - Processing equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a processing device, and more particularly to a structural architecture of the processing device.

[Prior art and its problems] In recent years, electronic musical instruments have been computerized. However, the part related to the generation of musical tones that require a large amount of high-speed data operation is performed by hardware of a special structure called a tone generator circuit, and the microcomputer controls input to the musical instrument (input from the keyboard or console panel, MIDI or other external control input, input from an internal or external performance memory, etc.) and only transfer commands appropriate for the tone generator circuit to the tone generator circuit.

The sound source circuit has a different structure depending on the method of synthesizing a musical tone, but any of the sound source methods has a large circuit scale. Typically, the circuit size is about twice as large as that of a microcomputer (central processing unit).

As an example, FIG. 11 shows a block diagram of a PCM sound source type. Microcomputer 101 for controlling PCM sound source 100
Exists, and information (commands) necessary for generating a musical sound in the PCM sound source 100 is sent from the microcomputer 101 to the PCM sound source 100. A command from the microcomputer 101 is set in each part of the sound source via the sound source command analysis unit 102.

For example, at the start of sound generation, information is set in the following procedure.

(A) Waveform storage device containing waveform to be sounded
Send the address for 107 (usually consisting of start address, end address, loop address). These addresses are set in the address control unit 104.

(B) Send pitch data of a musical tone to be sounded. The pitch data is set in the pitch control unit 105.

(C) Envelope controller by sending envelope data
Set to 106.

(D) Turn on channel control (Channel ON / OFF
Set in the control unit 103).

In the case of a polyphonic sound source, these data need to match the channel number, and each part of the sound source 100 must operate in a time division manner. When the above data is set, the PCM sound source 100 generates a musical sound as follows. At the corresponding channel time, the address control unit 104 reads from the waveform storage unit 107 the waveform data (the immediately preceding waveform value and the immediately following waveform value) at the two adjacent addresses closest to the pitch data accumulation result from the pitch control unit 105. . This waveform data is sent to the waveform processing unit 108, where the difference between the immediately preceding waveform value and the immediately following waveform value is calculated. This difference and the immediately preceding waveform value are sent to the interpolation circuit 109, where the difference between adjacent waveform values is added to the decimal part PD of the address of the waveform storage device (the pitch control unit in the figure).
105) and the immediately preceding waveform value is added thereto to obtain an interpolated value.
The instantaneous value of the musical tone waveform of the channel is obtained by multiplying the envelope value ED generated in step 6. This instantaneous value is accumulated for all the channels by the adder 110, and the result is sent to the D / A converter 111 to be an analog tone signal.

As can be seen from this example, the hardware of the tone generator circuit requires an arithmetic circuit and a storage device for temporarily holding data at every stage of the processing, and there is a problem that the circuit becomes large-scale. Further, the structure of the specific tone generator circuit only realizes the tone synthesis with the specific tone generator method and the specific polyphonic number. Even if the polyphonic number is simply changed, a significant circuit change or addition is inevitable. Further, it is necessary to design a set of commands to be sent from the microcomputer to the tone generator circuit in accordance with the tone generator, which requires a great deal of time and effort to develop a tone control program.

Next, a pitch control unit incorporated in the tone generator circuit hardware will be described. FIG. 12 shows a hardware configuration of the pitch control unit 105 in FIG. Addition address register shown
In the 201, pitch data representing the frequency of a musical tone is set from the microcomputer 101 via the sound source command analysis unit 102. This pitch data is added to the interpolation address register 2
03 is added to the output, and the sum is input to the interpolation address register 203 via the gate G. The carry terminal of the adder 202 outputs a carry signal at the time of addition, and this signal is input to the address control unit 104 in FIG. The address controller 104 increments the address of the waveform storage device 107 by one when the carry is output from the adder 202. On the other hand, the output of the interpolation address register 203 is input to the interpolation circuit 109 as an address interpolation value PD. The address interpolation value indicates the distance from the address of the waveform data read from the waveform storage device 107, and this data is hereinafter referred to as an address decimal part. On the other hand, the waveform storage device 10
The address for the physical storage location 7 is called an address integer part. That is, the phase of the waveform of the musical tone is determined by the address integer part and the address decimal part. Since the digital waveform storage device 107 cannot have a waveform value at an arbitrary phase, interpolation calculation of the waveform value is required.

The pitch control unit as exemplified in FIG. 12 cannot be used over a wide range. For example, consider a case where a sound having the same pitch as the original sound is reproduced at twice the sampling frequency recorded in the waveform storage device 107.
It must have a size of 0.5, which is half the distance between adjacent addresses in one data waveform storage device 107.
When the addition address register has a size of 15 bits and is expressed in binary, the size of 0.5 is 10000 00000 00000 (data A). At this time, a carry is output once every two times from the adder 202. In this case, the maximum value that can be set in the addition address register is clearly 11111 11111 11111 (data B). This is almost twice the frequency of the original sound indicated by data A, but does not reach one octave higher. This is the upper limit of the range that can be used by the pitch control unit in FIG. Certainly, the hardware can be complicated and used in a wider range, but it is not as effective as complex circuits. For example, in a high-grade sampling electronic musical instrument that requires high-quality musical sounds, waveform data (original sound data) of musical sounds of the same tone (for example, piano) are prepared for a large number of pitches and reproduced only in a limited range. Obviously, this method is only feasible at the expense of huge storage capacity.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problem of the sound source circuit hardware and the problem of the ability to reproduce a tone in a narrow range from the waveform data of the original sound relating to pitch control. It is an object of the present invention to provide a processing apparatus capable of generating a musical tone from a limited musical tone waveform data over a wide range or a desired range without increasing the storage capacity or complicating the circuit.

According to the present invention, in order to achieve the above object, a polyphonic musical tone is generated based on a control program for processing a control signal input supplied from the outside and a processing result of the control signal input. A program storage means for storing a musical sound generation program for generating in real time; an address control means for controlling an address for reading out a program stored in the program storage means; and Decoding means for decoding each instruction of the read program, waveform data storage means for storing sound waveform data, and necessary for generating musical tones generated according to each instruction of the control program decoded by the decoding means. Data storage means for storing important data, and data stored in the data storage means. Arithmetic processing means for performing arithmetic processing on the waveform data stored in the waveform data storage means in accordance with each instruction of the musical tone generation program decoded by the decoding means to generate a musical tone signal. The microcomputer executes the control program, activates and executes the tone generation program at predetermined sampling intervals independent of pitch, and generates a polyphonic tone signal in real time, Means for generating phase data consisting of an integer part and a fractional part representing the phase of the waveform of the tone from the pitch data representing the frequency of the tone, as a function of the microcomputer executing the tone generating program. , From the waveform data storage means according to the data of the integer part. Means for reading the waveform data at each of the addresses, and means for interpolating the value of the waveform data at the phase indicated by the phase data from the plurality of read waveform data and the data of the decimal part. A processing device is provided.

In the case of this configuration, the tone generation is performed by the microcomputer itself under program control of the microcomputer, so that the conventional tone generator circuit hardware is unnecessary. Further, by executing a program for generating a musical tone at each sampling time of musical tone generation, functions such as calculation of phase data from pitch data, reading of waveform data based on an integer part (upper bits) of the phase data, Since the means for interpolating the value of the waveform data at the designated phase using the read waveform data and the fractional part (lower bit) of the phase data is realized, the pitch data is provided with tone frequency information over a wide range. However, it is possible to generate a corresponding musical tone.
For this reason, no significant addition is required in terms of circuit scale and storage capacity.

In one configuration example, the microcomputer is realized by an integrated circuit chip, on which a digital-to-analog (D / A) converter for converting a generated digital tone signal to an analog signal and a musical instrument are provided in addition to the above-mentioned means. A port to receive input is also implemented.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of the electronic musical instrument according to the present embodiment.
The microcomputer 1 controls the entire apparatus. In particular, according to the present invention, the microcomputer 1 performs not only the processing of control input of the musical instrument but also the processing of generating musical tones.
, And does not require tone generator circuit hardware for musical tone generation. Switch section 4 composed of keyboard 2 and function keys 3
Is a control input source of the musical instrument, and information inputted from the switch unit 4 is processed by the microcomputer 1. The tone signal after analog conversion generated by the microcomputer 1 is filtered by the low-pass filter 5 and
And is emitted through the speaker 7. The power supply circuit 8 supplies necessary power to the microcomputer 1, the low-pass filter 5, and the amplifier 6.

FIG. 2 is a block diagram showing the internal structure of the microcomputer 1. The illustrated elements are mounted on one chip. The actually produced one has a chip size of 5 x 5 mm, has eight tones of polyphonic polyphony, and the tone synthesis method is PCM (waveform readout method). of course,
The polyphonic number can be easily changed within a range that maintains the sampling frequency for musical tone generation.

The control ROM 31 stores a program for processing various control inputs of the musical instrument and a program for generating musical sounds.
The program word (instruction) of the designated address is sequentially output from the ROM address control unit 39 via the ROM address decoder 32. In specific experiments, the program word length is
28 bits, part of the program word is RO as the lower part (address in page) of the address to be read next
Although the next address system is input to the M address control unit 39, the present invention can also be applied to a program counter system. The RAM address control unit 33 is a control ROM 31
If the operand of the instruction specifies a register, the address of the corresponding register in the RAM 34 is specified. The RAM 34 is a group of registers, and is used for general-purpose arithmetic, flag arithmetic, musical tone arithmetic, and the like. The adder / subtracter / logical operation unit 35 and the multiplier 36 are used when the instruction from the control ROM 32 is an operation instruction. In particular, the multiplier 36 is used for the calculation of the tone waveform, and as an optimization therefor, the first and second data inputs (for example, 16-bit data) are multiplied to obtain data having the same length (16 bits) as the input. Output. The RAM 34, the adder / subtractor 35, and the multiplier 36 constitute an arithmetic circuit (AU). Pitch data and envelope data (rate, level) in ROM 37 for control data and waveform
For example, various tone control parameters such as tone and tone waveform data of PCM (pulse code modulation) are stored. The envelope data and the tone waveform data are prepared for each tone color of the tone. Operation analysis unit (operation control circuit)
38 decodes the operation code of the instruction from the control ROM 31 and sends a control signal to each part of the circuit to execute the specified operation.

In order to execute the musical sound generation program in the control ROM 31 at predetermined time intervals, a timer interrupt is employed in this example. That is, the interrupt control unit 40 having a timer causes the ROM address control
9 transmits a control signal (interrupt request signal), and by this signal, the ROM address control unit 39 saves (holds) the address of the instruction of the next main program and generates an interrupt processing program (subroutine ) Is set instead. Thereby, the interrupt processing program is started. At the end of the interrupt processing program, there is a return instruction, and when this return instruction is decoded by the operation analysis unit 38, the ROM address control unit 39 sets the saved address again and returns to the main program. .

The input port 41 and the output port 42 are used for key scanning of the keyboard 2 and the function key 3. The tone generated in the interrupt processing program is converted into an analog signal by the digital / analog converter 43 and output to the outside.

FIG. 3A shows a flow of a main program of the microcomputer 1 of the present embodiment. A1 is the initial processing at the time of power-on,
(Register group) Clears 34 and sets initial values such as rhythm tempo. At A2, the microcomputer 1 outputs a signal for key scanning from the output port 42 and captures the state of the switch unit 4 from the input port 41 to store the state of the function keys and keyboard keys in the key buffer area of the RAM 34. . At A3, the function key whose state has changed is identified from the state of the function key 3 obtained at A2, and the designated function is executed (for example, a tone number set, an envelope number set, a rhythm number set, etc.). . In A4, the changed key (key pressed, key released) is identified from the state of the keyboard 2 obtained in A2.
In the next A5, a key assignment process for the sound generation process A9 is performed from the processing result of A4. In A6, when the demo performance key is pressed with the function key 3, the demo performance data (sequencer data) is sequentially read from the control data / waveform ROM 37 and processed, thereby performing key assignment processing for the sound generation processing A9. Do. At A7, when the rhythm start key is pressed, rhythm data is sequentially read from the control data / waveform ROM 37, and key assignment processing for sound generation processing A9 is performed. In the flow round timer processing A8, in order to know the timing of an event required in the main flow, the flow round time (this is obtained by counting the number of timer interrupts executed during one round of the flow. The process is performed in an interrupt timer process B3 described later.) To obtain an envelope timer (envelope calculation cycle) and a rhythm reference value. In the sound generation processing A9, various operations for actually generating a tone are performed from the data set in A5, A6, and A7, and the result is set in a tone generator processing register (FIG. 6) in the RAM 34. A10 is a preparation process for the pass of the next main flow, in which the NEW ON state indicating the change to the key pressed state obtained in this pass is set to ON or the NEW OFF state indicating the change to the key released state. Processing such as changing to OFF is performed.

FIG. 3B shows the flow of an interrupt processing program for generating a musical tone. In B1, the tone waveform data (cumulative waveform values for eight sounds) generated in the sound source processing B2 of the previous interrupt is sent to the D / A converter 43. As a result, a sample of a musical tone is given to the D / A converter 43 at a constant cycle. The following sound source processing B2 is a point of the embodiment. Conventionally, this processing is performed on the sound source circuit hardware. Details will be described later. In the next interrupt timer process B3, by taking advantage of the fact that an interrupt is taken at a predetermined time interval, the value is incremented by one every time the timer passes through the timer register (in the RAM 34) for counting one round of the flow.

In this embodiment, the contents of the registers to be written by the main program in the interrupt processing program are not rewritten. Therefore, the registers are saved at the start and end of the normal interrupt processing. No recovery process is required. That is, the registers on the RAM 34 are independent of the registers related to the tone processing and the registers related to other processing, so that the transition from the main program to the interrupt processing is performed with as little delay as possible.

The details of the sound source processing B2 are shown in FIG. 3C. RA for waveform addition with C1
After clearing the M area (see FIG. 6), processing C2 to C9 for eight channels is performed in order. At the end of each channel processing, the tone waveform value of the channel is added to the data in the RAM area for waveform addition.

FIG. 4 illustrates the flow of the operation of the embodiment over time. A, B, C, D, E, and F are fragments of the main program (FIG. 3A), and an interrupt process (FIG. 3B) is executed at regular intervals. FIG. 5 shows a time chart. As shown in the drawing, each time an interrupt occurs, a tone waveform signal is input to the D / A converter 43, and a corresponding analog signal is output to the outside.

FIG. 7 shows the processing of C2 to C9 in FIG. 3C in detail for one channel. Channel processing is roughly divided into envelope processing (D1 to D7) and waveform processing (D8 to D2).
Consisting of 1).

FIG. 8 shows an envelope generated by the envelope processing. The envelope of one musical tone consists of several steps (segments). In the figure, it is shown by four segments. In the figure, Δx is the sampling period of the envelope, and Δy is the change width of the envelope value. Channel envelope processing (D1 to D7)
In, the calculation of the envelope for each sampling time and the check of whether the target level of the step has been reached are performed. When the values match, the target value is set in the current envelope register (see FIG. 6). Therefore, the target value is detected in the sound generation processing A9 of the main program, and data (Δx, Δy, target (Envelope value) is set in each register.

More specifically, the timer register for comparing with the operation period Δx of the envelope is incremented in D1 for each interrupt, and when the value matches Δx in D2, the addition / subtraction flag (sign bit) of the data Δy corresponding to the envelope displacement is tested in D3. Then, it is determined whether the envelope is rising or falling, and the current envelope is subtracted or added at D4 and D5, respectively. At D6, check whether the current envelope has reached the target envelope value, and if so, set the target level to the current envelope. As a result, the data of the next envelope step is set in the sound generation processing A9 of the main program. Also sound processing A9
When the current envelope of zero is read, it is treated as the end of sound generation.

Next, the waveform processing D8 to D21 will be described. In the waveform processing, the waveform data of two adjacent addresses is read from the waveform ROM using the integer part of the current address, and (integer part +
The waveform value assumed for the current address indicated by the decimal part is obtained by interpolation. The reason why the interpolation is necessary is that the waveform sampling period due to the interrupt is constant, and the added value of the address (pitch data) covers a certain sound range for application to a musical instrument. Is widely available). Normally, the original sound is reproduced at a period faster than the recording sampling period of the original sound because the deterioration and distortion of the timbre due to interpolation are more remarkable in the high sound range. In this embodiment, the period of the original sound (A4) reproduction is set to 2
(Figure 9). Therefore, when the address addition value is 0.5, a sound of A4 can be obtained. In this case, in A # 4, the address addition value is 0.529, and A3
In the case of 1, it becomes 1. These address addition values are stored in the control data / waveform ROM 37 as pitch data.
When the key is depressed, in the tone generation process A9, the pitch data corresponding to the key and the waveform start address, waveform end address and waveform loop address of the selected timbre are stored in the corresponding register of the RAM 34, that is, an address addition value register,
It is set in the start address / current address register, end address register, and loop address register.

For reference, FIG. 10 shows the interpolated waveform data with respect to time. In the figure, white circles indicate waveform data values at the address of the waveform ROM, and black circles indicate interpolation values.

Although there are various interpolation methods, linear interpolation is employed here. The waveform generation processing D8 to D21 in FIG. 7 will be described in detail. First, at D8, an address addition value is added to the current address to obtain a new current address. D9 compares the current address with the end address. If the current address is greater than the end address, then according to D10 and D11, and if the current address is less than the end address, according to D12. , And the waveform ROM is accessed by the integer part in D14 to obtain the next waveform data. The loop address is the address following the end address in operation. That is, in the case of FIG. 9, the illustrated waveform is repeatedly read. Therefore, when the current address = end address, the waveform data of the loop address is read as the next address (D13). According to D15 and D16, the waveform ROM is accessed with the integer part of the current address to read the current waveform data. Next, the current waveform value is subtracted from the next waveform value in D17, the difference is multiplied by the decimal part of the current address in D18, and the result is added to the current waveform value in D19 to obtain the linear interpolation value of the waveform. Ask. The linearly interpolated data is multiplied by the current envelope value to obtain a tone data value of the channel (D20), and the resultant value is added to the contents of the waveform addition register to accumulate the tone data (D21).

Here, as shown in the sound source processing RAM table (FIG. 6), if the size of the address addition value register is set to be larger than the address decimal part of the start address / current address register (the data length of the start address or the current address in the figure) And the data length of the address addition value are the same), and the address addition value can be extended to an integer. This allows the generation of musical tone waveforms over a wide range. Further, the value range of the data actually set in the address addition value register can be easily changed by program control of the microcomputer. For example,
Depending on the musical sound, there is a sound (high quality sound) that is not suitable for reproducing as a musical sound over a range of ± 1 octave or more. Such a case can be dealt with without sacrificing storage capacity or adding a circuit. For example, limit data for the range of access to the pitch data table (in the control data / waveform ROM 37) is provided as control data for each tone color quality, and the control ROM 31 is used.
In the part of the program that converts the scale number of the key to pitch data, a load command for limit data corresponding to the quality of the selected musical tone, a routine for comparing the pitch data table address corresponding to the scale number with the limit data, It is sufficient to provide a routine for determining whether pitch data is issued for the comparison result or for recalculating the pitch data table address.

Finally, the circuit scale and operating time of a specific embodiment (8-tone polyphonic PCM sound source system) will be described.
112Kbit of ROM, 5.4Kbit of RAM34, RO for control data and waveform
M37 (100 tones) is 508Kbit. One machine cycle is about 276 nanoseconds, and the maximum number of interrupt processing program cycles during operation is about 150. Execution interval of interrupt processing (output sampling cycle of musical sound)
Is about 47 microseconds.

As described above, in the embodiment, the musical tone is generated by the program control of the microcomputer, and the interpolation calculation of the pitch-controlled waveform corresponding to the frequency of the musical tone is performed at each musical sound generation sampling time. The conventional tone generator circuit hardware is unnecessary, and the tone can be reproduced from limited waveform data over a wide range of pitch.

The description of the embodiment is finished above, but various modifications and changes can be made without departing from the scope of the present invention. For example, the interpolation calculation is not limited to linear interpolation.

[Effects of the Invention] As is clear from the above description, in the present invention, the tone generation is performed by the microcomputer itself under the program control of the microcomputer, so that the conventional tone generator circuit hardware is not required. Further, by executing the tone generation program for each sampling time of the tone generation, its function is to generate the next phase data by adding the pitch data and the current phase data, and to generate two adjacent waveform data according to the integer part of the phase data. The reading means implements means for interpolating the value of the waveform data at the position of the phase data based on the read waveform data and the fractional part of the phase data. It can be freely selected at the program level, and has the advantage that it does not increase the storage capacity or complicate the circuit configuration even when generating musical tones over a wide range.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an electronic musical instrument according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a microcomputer of the embodiment, FIG. 3A is a diagram showing a flow of a main program of the microcomputer, FIG. FIG. 3B is a flowchart of an interrupt process for generating a musical tone, and FIG. 3C is a flowchart of the interrupt process.
FIG. 3B is a detailed flowchart of the sound source processing, FIG. 4 is a diagram showing a flow of a program along time, FIG. 5 is a time chart showing an outline of the processing along time, and FIG. 6 is a RAM 34 in FIG. FIG. 7 is a detailed flowchart of one channel processing shown in FIG. 3C, FIG. 8 is a diagram showing an envelope, and FIG. 9 is a diagram showing waveform data of a waveform ROM. FIG. 10, FIG. 10 is a diagram showing an interpolation calculation waveform along time, FIG. 11 is a block diagram showing an example of conventional sound source circuit hardware, and FIG. 12 is a block of a pitch control unit incorporated in the sound source circuit hardware. FIG. 1 ... microcomputer, 31 ... control ROM, 34 ...
... RAM, 35... Adder / subtractor and logical operation unit, 36... Multiplier, 37... Control data and waveform ROM, 38... Operation analysis unit, 40.

Claims (2)

(57) [Claims] A program storage means for storing a control program for processing a control signal input supplied from the outside and a tone generation program for generating a polyphonic tone in real time based on a processing result of the control signal input. Address control means for controlling an address for reading a program stored in the program storage means; decoding means for decoding each instruction of the program read from the program storage means by the address control means; Waveform data storage means for storing shape data; data storage means for storing data necessary for generation of musical tones generated in accordance with each instruction of the control program decoded by the decoding means; storage in the data storage means Data and the waveform data stored in the waveform data storage means. Arithmetic processing means for generating a musical sound signal by performing arithmetic processing according to each instruction of the musical sound generating program decoded by the decoding means.The microcomputer executes the control program and By activating and executing the above-described tone generation program at predetermined sampling periods independent of pitch, a polyphonic tone signal is generated and output in real time. Means for generating phase data consisting of an integer part and a decimal part representing the phase of a musical tone waveform from pitch data representing the frequency of the musical tone as functions by executing the program; and from the waveform data storage means according to the data of the integer part. Means for reading waveform data at each of a plurality of addresses; Means for interpolating the value of waveform data at the phase indicated by the phase data from a plurality of read waveform data and the data of the decimal part. 2. The processing apparatus according to claim 1, wherein said microcomputer is constituted by an integrated circuit chip, and a digital-to-analog converter for converting a digital sound signal into an analog signal is provided on said chip and supplied from outside. A processing device, further comprising a port for receiving a control signal input.