JPH01259607A - White noise waveform generating circuit - Google Patents

Abstract

PURPOSE:To obtain plural different white noise waveforms with one type of equipment by controlling the operation of a polynomial arithmetic circuit and controlling the selection of number-of-stages switching circuits under a prescribed program by a control means. CONSTITUTION:A polynomial arithmetic circuit 33 receives the output of each stage of shift registers 21-25 cascaded to many stages and performs a polynomial calculation, number-of-stages switching circuits 31 and 32 provided on the output side of one or more stages of shift registers 21-25 select the outputs of the shift registers or the output of the polynomial arithmetic circuit 33 and output it to the next-stage shift register. A control means 34 controls the operation of the polynomial arithmetic circuit 33 and the selection of the number-of- stages switching circuits 31 and 34 under the prescribed program. Thus, by the control of the control means 34, the plural white noise waveforms can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a white noise waveform generation circuit for generating various noise sounds.

<Conventional technology> Many methods have been known to generate white noise waveforms, but it is extremely difficult to generate completely random waveforms, and this requires the use of hardware and software. It becomes quite complicated.

Therefore, when a complete white noise waveform is not required, such as for sound effects in video game equipment, a white noise waveform generation circuit using a shift register, which has simple hardware and is less dependent on software, can be used. A pseudo white noise waveform was generated.

<Problem to be solved by the invention> By the way, since the pseudo white noise waveform generated by the white noise waveform generation circuit using such a shift register has a specific periodicity, The timbre of the noise waveform varies considerably depending on the configuration, but conventional white noise waveform generation circuits have a fixed configuration of this shift register for each model, so there is a problem that only a certain white noise waveform can be generated. . For this reason, if a special sound effect is required for each game or if multiple different white noise waveforms are required, such as in a video game device, it is necessary to use a model with a different shift register configuration each time. There was a problem that it was troublesome.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a white noise waveform generation circuit that can generate a plurality of different white noise waveforms with a single model.

Means for Solving the Problems> In order to achieve the above object, the white noise waveform generation circuit of the present invention includes shift registers connected in cascade in multiple stages, and a polynomial that performs a polynomial operation in response to the output of each of the shift registers. Provided on the output side of the arithmetic circuit and one or more stages of the shift registers, selects the output of the shift register or the output of the polynomial arithmetic circuit and outputs it to the next stage shift register. The present invention is characterized by comprising: a stage number switching selection circuit; and a control means for controlling the calculation of the polynomial calculation circuit and controlling the selection of the stage number switching selection circuit based on a predetermined program.

Function> The output of each stage of shift registers connected in cascade in multiple stages is
A polynomial arithmetic circuit receives the signal and performs a polynomial arithmetic operation, and a stage number switching selection circuit provided on the output side of the shift register of one or more stages selects the output of the shift register or the output of the polynomial arithmetic circuit. and outputs to the next stage shift register. A control means controls the calculation of the polynomial calculation circuit and the selection of the stage number switching selection circuit based on a predetermined program. Therefore, a plurality of white noise waveforms can be obtained by controlling the control means.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

Figure 1 shows white noise in which a polynomial calculation circuit 2 receives the output of each stage of shift registers l connected in series in n stages, and feeds back the polynomial calculation output signal to the shift register l to obtain a white noise waveform. A waveform generation circuit is shown.

FIG. 2 shows a white noise waveform generation circuit of this embodiment using a polynomial arithmetic circuit and a 7-foot register as shown in FIG. In this circuit, the maximum number of stages of shift registers is m, and the output 1 of the m-th stage shift register 21 is
The output side of the (n+1)th stage shift register 22 is provided with stage number switching circuits 31 and 32, respectively. and,
The output of each shift register is output to a polynomial calculation circuit 33, and the polynomial calculation output of this polynomial calculation circuit 33 is fed back to the stage number switching circuits 31 and 32 as a feedback signal.

The stage number switching circuits 31 and 32 receive a stage number signal output from the CPU 34 as a control means according to a predetermined program, select either the output of the shift register of that stage or the feedback signal, and shift the stage to the next stage. It is designed to be output to a register. When the feedback signal is selected, the number of stages of the shift register is truncated at that point. That is, when the stage number switching circuit 31 selects the feedback signal, it becomes a (m-1) stage shift register, and when the stage number switching circuit 32 selects the feedback signal, it becomes an n stage shift register.

Further, the CPU 34 outputs a polynomial calculation control signal to the polynomial calculation circuit 33 according to the program to determine the logic of the polynomial calculation, select the operand signal used in the calculation, or select one of the plurality of polynomial calculations. Control is performed such as selecting the necessary polynomial calculation output from the input signal and using it as a feedback signal.

In this way, the number of stages of the shift register and the method of creating the calculation output signal of the polynomial calculation circuit are determined and output by the "stage number signal" and the "polynomial calculation control signal" outputted from the CPU 34 as a control means by the above program. A white noise waveform is determined.Therefore, by changing the number of shift register stages and the method of creating a calculation output signal using this program, a plurality of different white noise waveforms can be obtained.

FIG. 3 is a flowchart explaining this operation. First, when the required white noise waveform is determined, the number of stages of the shift register and the calculation of the polynomial calculation circuit are determined accordingly, and the white noise waveform generation circuit is uniformly determined. The desired white noise waveform is then generated by this white noise waveform generation circuit.

<Effects of the Invention> As is clear from the above, the white noise waveform generation circuit of the present invention includes a polynomial calculation circuit that performs polynomial calculation in response to the output of each stage of shift registers connected in cascade in multiple stages, and the shift register described above. A stage number switching selection circuit is provided on the output side of one or more stages of the shift register, and selects the output of the shift register or the output of the polynomial arithmetic circuit and outputs it to the next stage of the shift register. Since the control means controls the calculation of the polynomial calculation circuit and the selection of the stage number switching circuit based on a predetermined program, it is possible to obtain a plurality of different white noise waveforms with one model. can.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining a white noise waveform generation circuit consisting of a shift register and a polynomial calculation circuit, Fig. 2 is a block diagram showing an embodiment of the white noise waveform generation circuit of the present invention, and Fig. 3 is a diagram illustrating the above implementation. 12 is a flowchart illustrating an example operation. 1.21-25...shift register, 2.33...
Polynomial calculation circuit, 31.32... Stage number switching circuit, 34... CPU.

Claims (1)

[Claims] (1) Shift registers connected in cascade in multiple stages, a polynomial calculation circuit that receives the output of each of the above shift registers and performs a polynomial calculation, and the output side of the shift register of one or more stages of the above shift registers. a stage number switching selection circuit that selects the output of the shift register or the output of the polynomial calculation circuit and outputs it to the next stage shift register, and controls the calculation of the polynomial calculation circuit based on a predetermined program. A white noise waveform generation circuit comprising: a control means for controlling selection of the stage number switching selection circuit;