JP2604695B2 - Computer device with intermediate address interrupt - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ADP from an external storage device such as a computer game device using a CD-ROM.
The present invention relates to a method for generating an interrupt in a computer device that receives audio data such as CM data and performs long-time reproduction.

[0002]

2. Description of the Related Art At present, digital sound systems have become mainstream in computer game devices. In the digital system, all audio signals are obtained as numerical values, and waveforms can be easily synthesized by addition, subtraction, multiplication, and division operations.

Computers are used because high-speed data processing capability is required to synthesize waveforms by calculation. In order to obtain a sound source, there is a method of generating a sound by creating a waveform by programming. However, in order to obtain a sound source of high sound quality, a target analog sound is often converted into a digital signal.

[0004] In order to digitize an audio signal, a pulse code modulation method (PC) which is an analog signal general A / D conversion method is used.
M) is used. PCM is a method of obtaining digital data by sampling an analog signal at fixed time intervals and converting a numerical value obtained by quantizing a measured value into a binary number.

[0005] Differential PCM (DPCM) with improved PCM
Is a method in which the difference between the values of adjacent samples is taken and quantized to reduce the data amount. Adaptive Differential PCM (ADP
CM) further compresses the data by reducing the sampling pitch when the difference is large and increasing the pitch when the difference is small, thereby minimizing sound quality damage and reducing the amount of data. It reproduces the sound.

[0006] PCM data is mutually converted to ADPCM data having a small data amount by a compression / expansion coefficient composed of a scale value and a scale level.

[0007] Although computer games did not handle sound in the early stages, with the advance of technology, a programmable sound generator (PSG) having a small size and a small data amount was first used.

The PSG generates an audio waveform created by performing amplitude change and frequency modulation by calculation from waveform data for a fixed period given under the control of a central processing unit (CPU). In some cases, noise is generated by directly generating a simple waveform. PSG audio output is easy to control, but it is difficult to obtain free sounds.

As a sound source for obtaining free sound, the above-mentioned ADPCM system capable of obtaining high-quality sound is employed. ADPC for computer game devices based on the amount of data that can be handled by general computer game devices
The sampling frequency of the M decoder is around 16 kHz.

The CPU reads out audio data previously written in the attached storage device in the form of ADPCM data, and the ADPCM decoder expands the data by referring to the scale value and the scale level to reproduce sound.

The ADPCM decoder in the sound generator is
It has a built-in synchronization signal generation circuit that creates a transfer rate. By reproducing PCM data and outputting it as audio in accordance with a transfer rate set by a synchronizing signal generated from a crystal oscillator, the timing of generation of musical sounds or sound effects is controlled.

In recent computer game machines, PS
In addition to a sound source whose output is controlled by a CPU such as G and ADPCM, it is connected to an external audio device to obtain an output of high sound quality. For example, in a game device in which a compact disk (CD) is introduced as a storage medium for game software, a CD player is directly used as a PCM sound source to obtain high-quality sound.

[0013]

In a process of continuously reading data in a memory, it is necessary for a user to manage how much data has been read by a program.
Even so, there is no problem when reading while directly specifying the address because the address is known.

However, when reading memory data such as ADPCM, since the system automatically accesses the data at a predetermined time interval, it is not possible to directly know how far the data has been read. For this reason, the position currently read must be calculated from the elapsed time.

As a matter of course, such a monitoring method increases the load on the CPU and adversely affects other processes. In particular, processing in a computer game machine includes HSYNC (horizontal synchronization) and VSYNC (vertical synchronization)
Since processing in a short period of time is required, taking a CPU during this calculation time imposes a heavy burden on a system that requires high-speed processing.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce a load on a CPU in a continuous reproduction process such as a continuous sound reproduction process in a computer device.

[0017]

The sound reproducing process in the system of the present invention has a system configuration as shown in FIG. The original data of the sound is stored in the CD-ROM. It is read by a chip with SCSI controller and sound controller functions and dedicated RAM
Is read and stored in the ADPCM area of the K-RAM.

This data is transferred to the sound reproducing chip at a certain timing. Sound reproduction chip (SOU
NDBOX) reproduces the data and generates sound through a speaker. The arrows in FIG. 1 indicate the flow of data.

All the sound data on the CD-ROM
-It is only necessary to read them into RAM at once, but ADPC
Since the capacity of the M area is limited, not all of the data can be read in the memory.

In such a case, it is necessary to read the continuous data again into the data area reproduced halfway as shown in FIG. 2 and prepare in advance for the next reproduction. Otherwise, if the next new data is read after all the data has been reproduced, the sound is interrupted while the data is read, resulting in intermittent sound reproduction.

In the present invention, the checkpoint can be set by a program, and is incorporated in the hardware of the sound controller so that an interrupt occurs when an access comes to this point.

After the data of the end address of the data area provided in the data buffer memory is transferred, the point is automatically shifted to the start address to set the ring mode for continuous reproduction, and the check point set between the start address and the end address is set. When the point reaches the intermediate address and the end address, an interrupt is generated.

Continuous reproduction is possible by updating the first half of the data in response to the intermediate address interrupt and updating the data of the second half in response to the end address interrupt. According to the computer apparatus of the present invention having such a function, it is not necessary for the software to check how much data has been processed, and the reading of new data can be easily performed in the interrupt routine.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Let's see how to use interrupt processing. FIG. 3 is a block diagram showing one embodiment of a computer game device incorporating the chip of the present invention. FIG. 4 is a more detailed diagram of a chip including the SCSI controller, graphic controller, sound controller and the like in FIG.

In the sound controller, a checkpoint causing an interrupt is set in the SOUND half address register. This register has # 1 and # 2,
# 1 is for channel 1 and # 2 is for channel 2.

Assume now that only channel 1 is used. Whether or not to generate an interrupt can be determined by the SOUND buffer control register. Therefore, it is assumed that an interrupt is generated when the middle point m and the end point e of the ADPCM data area are reached. To do so, the following is set in the SOUND buffer control register # 1.

RING BUF = 1 (ring buffer mode) BUF END = 1 (interrupt occurs when end point is reached) BUF HALF = 1 (interrupt occurs when intermediate point is reached)

The ring mode is a mode for automatically returning to the start point when the end point is reached and reading data again. The start point and the end point are set by a SOUND start address register and a SOUND end address register. On the other hand, as shown in FIG. 5, the intermediate address m of the ADPCM data is designated in the SOUND half address register # 1.

When the sound processing is executed in this manner, an interrupt is generated at addresses m and e. When an interrupt occurs at point m, new data is read into the data area (A in FIG. 5) which has been processed up to that point.

When an interrupt occurs at point e, new data is read into the data area (B in FIG. 5) which has been processed up to that point. FIG. 6 is a flowchart of the above processing.

In the drawing, various processes represent general processes for displaying images and preparing for the same in a game. This includes sound generation in SOUNDBOX and transfer of sound data from the K-RAM for that purpose.

However, this is the default setting for various SOUNDs.
Once you set the registers, the system does it automatically, so you don't have to touch the program directly.

Similarly, the system generates an interrupt at the intermediate point m or the end point e by checking the contents of the SOUND register. Of course, the processing in the interrupt processing needs to be handled by the user. That is the interrupt processing at the intermediate point m shown in FIG. 4 and the interrupt processing at the end point e.

[0034]

According to the interrupt function of the intermediate address of the present invention, the interrupt at the checkpoint can be automatically generated by hardware only by setting the necessary items in the register for SOUND. Time is faster.

Particularly when a long time sound reproduction is required, a great effect can be obtained. I mean,
This is because the user program does not need to check the intermediate point at all while other processing is being executed. As a result, the burden on the CPU is reduced, and the burden on the CPU, which has been checking the intermediate point, can be transferred to other processing.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a flow of sound data in a computer game device.

FIG. 2 is an explanatory diagram showing a relationship between transfer timing when sound data is read from a CR-ROM to a KRAM and a reception area.

FIG. 3 is a block diagram of a computer device according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a chip including a sound controller of the computer device according to the embodiment of the present invention;

FIG. 5 is an explanatory diagram of a relation between a SOUND address register and an ADPCM data area.

FIG. 6 is a flowchart of an interrupt process using an intermediate point address according to the present invention.

Claims (1)

(57) [Claims] An audio data is transferred from an external storage device.
Read into the buffer memory
Reads and reproduces data at appropriate timing and outputs audio
In a computer device for outputting, the audio data
The buffer memory is used to store the end address of the data area.
Automatically transfer point to start address after data transfer
And the voice recorded in the voice data buffer memory
Configure a ring buffer memory for continuous data playback,
And set between the start address and end address
To the specified intermediate address and the end address.
That a means to generate an interrupt when the
Computer device characterized by the following.