WO1998043401A2 - Software implementation of modem on computer - Google Patents
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- WO1998043401A2 WO1998043401A2 PCT/US1998/003461 US9803461W WO9843401A2 WO 1998043401 A2 WO1998043401 A2 WO 1998043401A2 US 9803461 W US9803461 W US 9803461W WO 9843401 A2 WO9843401 A2 WO 9843401A2
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- modem
- datapump
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- 230000003139 buffering effect Effects 0.000 claims description 9
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
- H04M11/06—Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
Definitions
- the invention relates to data communications and, in particular, to a software implementation of a modem that can operate on a general purpose computer having a non-real-time, multi-tasking operating environment.
- Modern modems are used to connect PCs, or other data terminal equipment (DTE), into wide area communication networks, in which the telephone system is used to carry information from one PC to another.
- DTE data terminal equipment
- These protocols specify various aspects of a communication protocol, such as signai constellations and coding methods to be used under the standard.
- modems have been typically implemented with special circuitry, or programmable digital signal processors (DSPs).
- DSPs programmable digital signal processors
- a microprocessor and a DSP would effectively cooperate in a master-slave relationship.
- the microprocessor would act as a "controller,” handling the control functions, such as configuring the system and the like, and the DSP would essentially act as a dedicated computation engine to handle the signal processing aspects.
- the above typical arrangement would operate in a "real-time" context. That is, both the microprocessor and the DSP would be dedicated to running the modem controller and DSP software, respectively.
- a real-time context provides deterministic behavior, and deterministic behavior, in turn, is desirable in the modem context, because modem data streams are continuous and arrive at fixed rates.
- the DSP and other dedicated hardware involve component costs. Moreover, they add to the associated manufacturing, distribution and maintenance costs and affect reliability of the overall system.
- Fig. 1 is a architectural diagram of the hardware of an exemplary embodiment of the invention
- Fig. 2A is an interrupt model of traditional, prior art modems
- Fig. 2B is an interrupt model of an exemplary embodiment
- Fig. 3 is a software architectural diagram illustrating an exemplary embodiment of the invention operating in a multi-tasking, preempatble operating system
- Fig. 4 is a software architectural diagram illustrating various subsystems of an exemplary embodiment of the invention
- Fig. 5 illustrates the priority levels at which various subsystems operate according to an exemplary embodiment of the invention
- Fig. 6 illustrates priority level assignments together with subsystems of an exemplary embodiment of the invention
- Fig. 7 shows aspects of a selected datapump of an exemplary embodiment of the invention
- Fig. 8 shows the logic of the HRT interrupt service routine of an exemplary embodiment of the invention
- Fig. 9 shows the logic of a transmit portion of a datapump of an exemplary embodiment of the invention.
- Fig. 10 shows the logic of a receive portion of a datapump of an exemplary embodiment of the invention.
- Fig. 11 shows a block diagram of a transmit portion of a datapump of an exemplary embodiment of the invention.
- the exemplary embodiments of the invention are software implementations of a modem, particularly designed to execute on a host processor, controlled by a non-real-time, multi-tasking operating system (OS), such as the Windows 95 OS.
- OS non-real-time, multi-tasking operating system
- the software design of the modem is scaleable and portable. In this fashion, communication protocols (particularly datapumps) may be easily added to, or removed from, the system, and the modem may be easily adapted for use on other types of processors and operating systems.
- the exemplary embodiments require a relatively minimal amount of hardware in addition to the host PC.
- Figure 1 shows one such exemplary arrangement in the form of an ISA card.
- This hardware arrangement is discussed in detail in co- pending U.S. Apl. No. 08/607, 911 to Sridhar et al., which is assigned to the assignee of this application and which is hereby incorporated by reference in its entirety.)
- This hardware arrangement is outlined below only to the extent necessary for understanding the exemplary embodiments of the invention.
- the exemplary hardware arrangement 100 includes a host processor 102, coupled to an ISA bus 104, which is coupled to an ISA card 105.
- the ISA card includes an exemplary ASIC 106, which communicates on the bus 104 via IRQ/Addr/Data lines 114.
- the ASIC 106 is coupled to a voice codec 108 and a data codec 110, which is coupled to a data access arrangement (DAA).
- DAA data access arrangement
- the voice codec 108 coupled to a microphone input and a speaker output, and the DAA is coupled to phone lines 116.
- the codecs 108, 110 perform the A/D and D/A conversions.
- the ASIC includes receive and transmit data FIFOs 118r and 118t, which hold, respectively, samples of data to be eventually demodulated and processed by the software modem and samples of data already modulated and processed by the software modem but which need to be converted to analog form.
- the ASIC 106 further includes receive and transmit voice data FIFOs 120r and 120t, which hold voice data, for example in 8 bit PCM (e.g., ⁇ -law), to be used by the host processor 102.
- PCM e.g., ⁇ -law
- the FIFOs' size and control thereof allow for extended interrupt latencies to the host processor 102.
- the actual sizes and control thereof of exemplary embodiments are discussed in the co-pending application.
- the exemplary arrangement 100 is shown as an ISA card arrangement, skilled artisans will appreciate that the invention is applicable to other arrangements.
- analogous logic may be implemented in alternative ASIC arrangements in which the FIFOs are implemented with memory chips external to the ASIC, or in which the codecs are implemented in the ASIC.
- alternative arrangements may be implemented on the motherboard containing the host processor 102, rather than on an ISA card, and the voice codec and FIFOs are optional.
- Figures 2A-B together compare the "interrupt models" of a typical DSP arrangement and of an exemplary embodiment of the software modem.
- Figure 2A shows the interrupt model for a typical DSP arrangement. Under this model, one symbol (or baud) of data is processed by the modem per interrupt. This symbol of data could correspond to several samples of data, e.g., 3.
- Figure 2B shows the interrupt model of an exemplary embodiment. For example, for a given hardware interrupt 90 samples (at 7.2KHz sampling rate) may be retrieved, corresponding to 30 symbols for a data pump operating at 2400 baud and the system having a 3X sampling rate. Under this model, the ASIC 106 gathers many symbols and generates interrupts to the host PC 102 at substantially regular intervals. The software modem, executing on the host PC, will respond to the interrupts by gathering the several samples and processing them according to modem algorithms.
- the buffering and interrupt model of Figure 2B provides several advantages.
- a lower interrupt rate improves performance of the system by reducing the number of context switches to and from the interrupt service routine, so that not only are fewer instructions executed (i.e., the ones involved with the context switch) but cache utilization is improved.
- the host PC can dynamically adjust FIFO depth and the interrupt rate.
- one interrupt rate may be used for steady state operation and another may be used during certain phases of the start-up sequence where some tight timing requirements exist.
- the interrupt rate is set to be about 12 to 12.5 ms and during certain start up phasesthe rate is set to 2.5 ms.
- the rate is set to 2.5 ms.
- about 90 samples of data are handled for a host processor interrupt during steady state operation and about 18 samples during interrupts in the ranging phase of the V.32.
- FIG. 3 shows a high-level software architectural diagram of an exemplary embodiment of the invention that is intended for the Windows 95 OS.
- the software components surrounded by dashed section 310 are conventional Windows OS infrastructure, including conventional infrastructure for having applications 320 communicate with a traditional modem 319 if it were connected to the system.
- the software applications 320 are representative of various applications that may cause communication via a modem link.
- the software modem in one sense includes the components of section 330.
- the core of the software modem is the Soft Modem VxD 334 (host-based modem).
- the UART VxD 332 is a software emulation of a conventional UART and is useful in allowing DOS applications, for example, to be used in the illustrated environment. (UART emulations are commercially available.)
- the line interface card 336 refers to all of the hardware outlined above in its various forms.
- the host-based modem 334 integrates with the OS infrastructure through the OS's VCOMM entity 314, using conventional techniques. In short, under this model, the host-based modem 334 effectively registers itself with VCOMM as a serial communications device. It is also registered with and controllable by the OS's Unimodem V entity 312 as a data/fax/voice modem, again using conventional techniques. Any application 322, 324 wishing to communicate using the modem has its requests routed through the OS infrastructure 310 and particularly through VCOMM 314 to the appropriate entry points of the host-based modem 334. If a hardware modem 319 were used, the requests would be routed by VCOMM 314 though serial VxD 316, part of the OS infrastructure 310, to a hardware UART 317 and eventually the hardware modem 319.
- FIG. 4 shows a more detailed software architecture 400 of an exemplary host-based modem 334.
- the architecture has various subsystems.
- Each subsystem may have software logic executing at, or responding to software executing at, one of three levels: HRT, SRT, BRT (from highest priority to lowest).
- the OS recognizes other levels of priority as well, for example, for applications 320.
- the OS will make scheduling decisions based on predefined scheduling rules.
- an appplication program which operates at a priority lower than BRT, would have a maximum amount of time in which it could use the host processor 102, before it would have to yield control.
- a given level of priority e.g., BRT could be preempted by a higher level routine, such as a HRT routine, even if the BRT routine had not yet finished.
- the host-based modem 334 is more able to balance the competing needs of handling an effectively real-time stream of data and of economically using the host processor's resources. This may be clearer by considering a crude design. A crude design would have the entire host-based modem operate at the highest priority level. Because the logic would operate at only the highest priority level, it could not be preempted by other routines, and thus would make the environment somewhat similar to a traditional real-time environment.
- HRT is short for Hard Real-Time and is implemented as a hardware interrupt service routine (ISR).
- ISR hardware interrupt service routine
- the HRT logic may be thought of as being responsible for handling the transmit and receive FIFOs 118, 120 (Fig. 1 ).
- the HRT routine implements portions of the SoftChip datapumps 410, in particular for the digital signal processing aspects and time-critical portions of the state machine control logic.
- the HRT logic includes portions of the ASIC driver 465 and portions of the System Services 455 that are invoked at a baud-level. The HRT task is invoked as a result of interrupts from the ASIC hardware (about every 12 to 12.5 ms). How the logic is invoked is discussed below.
- SRT is short for Soft Real-Time and is implemented as a global event routine, for example, in the Windows 95 OS.
- the HRT ISR posts global events on every other triggering of the HRT ISR.
- SRT routines are triggered approximately every 25 ms.
- One of the subsystems called the central dispatch (CD), among other things, keeps an SRT timer queue.
- CD central dispatch
- any of the various subsystems in 400 need to perform timing or monitoring operations, for example, monitoring a time out, they post references to a callback routine in the CD's SRT timer queue. The timer queue will then invoke the callback at the proper time.
- the subsystem that posted the callback may monitor elapsed time and the like, as is necessary to implement the communication standards.
- the actual callback routines referenced in the timer queue varies dynamically with the state of the host-based modem system 334.
- the host-based modem may need to monitor a time-out condition at some instants in time but not at others.
- Callbacks may be entered in the timer queue with various switches.
- the callback may be registered with information indicating that it should remain in the queue until cleared or until a specified time-out.
- the callback may be registered with an indication that after a specified time, a specific event should be posted in the BRT event queue, (more below)
- the HRT software logic was summarized as being responsible for transmit and receive FIFOs
- the SRT logic may be thought of as being responsible for the various "timer routines" typically found in a modem.
- typical modems have various functions to measure elapsed time or to monitor, or poll, certain signals.
- BRT is short for Background Real-Time and is the lowest priority level used by the host-based modem 334, but not necessarily by the overall PC system. As will be described below, the host-based modem 334 actually uses 2 separately, schedulable BRT routines.
- the central dispatch 415 includes an event queue.
- invocation of the callbacks in the SRT queue are time-based with a granularity of 25 ms
- the invocation of BRT routines is event and message based with no time granularity.
- the various subsystems used in the host-based modem 334 communicate with one another via events and messages.
- a data IO unit 450 may be first used in receiving the character stream and upon detecting a carriage return it would post an event to the autocall unit 430 informing it that an AT command has been received.
- the host- based modem at a subsystem level of description may be thought of as a large state machine in which state transitions are triggered by events.
- a subsystem needs to essentially go into a "sleep state," for example, a subsystem may need to wait for a response or time out.
- the SRT queue therefore, includes a mechanism for posting events in such cases.
- an event would be posted to the subsystem waiting for a response or the time-out, thus waking it from its wait, or sleep, state and informing the subsystem of the time-out.
- SRT and BRT effectively are subpriority execution levels.
- the overarching execution priority level corresponds to the global event, posted by HRT.
- the global event is routed through system services 455 to a callback routine in CD 415 corresponding to SRT scheduling logic.
- the SRT scheduling logic effectively implements the subpriorities, by first processing the callbacks on the SRT timer queue. Afterwards, events on the main BRT event queue are processed, followed by the EC BRT logic.
- Both of the BRT groups include logic to make sure they only do limited processing and that they do not starve other routines of resources (e.g., loop counting logic).
- An alternative embodiment of the invention implements the above logic executing at BRT priority level as two separate tasks at an application level of execution priority. Though this embodiment offers the advatages of the OS-level of support of execution priority and of time-slicing the BRT routines (to avoid starving other applications) it may be susceptible to delay, when the user has a large number of concurrently running applications.
- the common core includes SoftChip Datapump section 410, Central Dispatch (CD) 415, Master Control 420, Configuration Management 425, Autocall Command Processing 430, Protocol Processing 435, Soft Chip Control 440, and Test 445.
- the SoftChip Datapump section handles all datapump and signal processing functions, such as tone generation, call progress, call classification and the other traditional datapump and signal processing functions. These functions may depend on the corresponding standard, such as V.34, V.32bis, etc., each of which would have a corresponding datapump that could be coupled into the architecture and each of which would be integrated into the SoftChip Datapump section 410.
- Each datapump within the SoftChip Datapump 410 includes essentially two types of code: state machine control and digital signal processing code (not to be confused with code for DSPs).
- the source code is designed to be highly portable.
- the digital signal processing section is implemented using macros, which effectively force the compiler to compile the macros in a certain way, for example, into a particular sequence of machine instructions. (Later sections describe other aspects used to improve portability and scaleabilty)
- the Central Dispatch (CD) 415 manages event (BRT) and timer queues (SRT). In short, for background and timer priority levels, the main processing loop starts here and control is dispatched into an appropriate subsystem based on the state of the queues.
- BRT event
- SRT timer queues
- Master Control 420 provides higher level control functions such as connect/ disconnect handling; for example, informing the various subsystems in a specified sequence about disconnects.
- Configuration Management 425 maintains a configuration database analogous to that performed with conventional modem controllers.
- the software logic for this section is conventional, allowing for configuration of baud rates, flow control, etc., as is the case in traditional modems.
- Autocall Command Processor (ACU) 430 processes commands from the terminal, analogously to conventional modem controllers. These commands may be in different known formats, such as AT, V.25bis and LPDA.
- the Protocol Processor (PP) 435 handles data mode protocols.
- this section includes the software logic to support Error Correction/ Data Compression (EC/DC) with MNP 2-5 and/or V.42bis.
- EC/DC Error Correction/ Data Compression
- This section may also support other protocols, such as for fax , cellular, or simultaneous voice transmissions.
- Data compression logic could include macros with platform specific optimizations.
- This portion includes its own separately schedulable BRT task for error correction (EC) logic, which is organized in this fashion to minimize the risk of EC logic starving the other BRT threads.
- EC error correction
- the Soft Chip Control 440 translates events into proper control settings for the Soft Chip Datapump 410.
- the SoftChip Datapump has an interface analogous to that of dedicated DSPs to improve portability and scaleability. Among other things, this allows datapumps to be written for exemplary embodiments or for DSPs. This control will translate the events posted to Soft Chip Control 440 into the appropriate register settings to initiate the datapumps into action.
- Test Section 445 includes testing and diagnostic support logic.
- the more platform-specific aspects of the architecture 400 include a Data IO section 450, a System Service Interface 455, a Serial Driver Interface 460, and an ASIC driver 465.
- the Data IO section 450 provides lower level services for internal data transfers, for example, emulation of useful peripherals such as serial communication controllers (SCCs), e.g., asynchronous framing functions and HDLC framing.
- SCCs serial communication controllers
- asynchronous framing functions e.g., asynchronous framing functions
- HDLC framing e.g., HDLC framing
- the System Services Interface 455 insulates the above- described core from the operating system, such as the Windows 95. In this manner, the host-based modem 334 may be largely OS- independent with many of any necessary dependencies residing in the System Services Interface 455.
- the ASIC driver 465 provides the software logic for interfacing with the above-described hardware. It is primarily responsible for reading data from and writing data to the ASIC FIFOs.
- Figure 6 combines elements of Figures 4 and 5 so that priorities and data flow are more evident.
- Figure 6 illustrates that as a general matter the closer the software logic is to the hardware, the higher the priority level the software will execute at.
- Figure 5 shows the priority assignments associated with the various subsystems, along with the task assignments.
- the figure shows that there are 2 BRT tasks, one for the protocol processing and particularly for the EC logic, and a second for all of the logic having invoked as a result of the BRT event queue.
- the SRT task so to speak, is the collection of callbacks registered in the CD timer queue and triggered as a result of the global event (approximately every 25 ms).
- the HRT task is essentially the HRT ISR, responding to ASIC 106 interrupts, (this is described in more detail below)
- Figure 6 combines elements of Figures 4 and 5 to illustrate that, as a general matter, the software subsystems that are on the data path operate at HRT and SRT levels, with the subsystems closer to the ASIC running at HRT, and that the entities on the control path operate at BRT.
- FIG. 7 illustrates a portion of one datapump 410A as part of the SoftChip Datapump section 410.
- the SoftChip Datapump section 410 includes datapumps for the various communication standards, e.g., V.34, V.32bis, V.32, fax standards, etc., plus automode processing
- the datapump 410A includes a control/data structure 710. that includes an interface section 71 1 for interfacing with SoftChip Control section 440.
- This interface is modeled as a register-based interface, like interfaces used in traditional modems, but is extended in other ways, for example, for the fax-related datapumps.
- Finite State Machine Variables (FSM Vars) Section 712 holds data indicative of the various variables considered in determining whether a data pump state change is appropriate.
- DSP Vars Section 713 contains variables used by the datapump algorithms.
- Control Section 714 includes modem state 714a, transmit vector 714b, receive vector 714c, transmit DSP vector 714d, and receive DSP vector 714e.
- the transmit DSP vector 714d and receive DSP vector 714e are pointers, respectively, transmit and receive DSP tasks.
- the transmit vector 714b and receive vector 714c are pointers, respectively, to transmit and receive state logic; this state logic consider the modem state and other variables in determining whether to modify the modem state 714a.
- the HRT ISR When the ASIC 106 generates an interrupt, the HRT ISR is eventually invoked. Typically, the latency is small between the generation of the interrupt and the time the ISR is invoked, but the time can vary and become large if another ISR is executing at the time the interrupt is received, thus blocking the HRT ISR from execution.
- the HRT routine starts at step 801 and proceeds to step 810.
- the HRT routine reads the samples from the RX FIFO 118r of the ASIC 106.
- the number of samples depends on various things such as the sampling rate of the codecs and the programmed interrupt rate for the ASIC 106.
- 90 samples of data would be read.
- the logic proceeds to step 820 where it is determined whether more bauds, or symbols, need to be processed. For example, if 3x sampling were used, the 90 samples would correspond to 30 bauds.
- the amount of baud to be processed depends on the datapumps involved, as well as the sampling and baud rates. If more bauds are to be processed, the logic proceeds to step
- step 830 where a transmit baud is processed.
- This step 830 involves accessing the state control logic pointed to by txvec 714b in the data/control structure 714b for the selected datapump 410a.
- the state control logic pointed by txvec 714b will look at the modem state 714a and the various variables in the control structure 710 and update the modem state accordingly, all corresponding to the datapump's specific algorithms.
- step 830 then processes the samples (e.g., 3) corresponding to the next baud to be transmitted. This is done by referencing the software logic pointed to by txdspvec 714d in control structure 710.
- Txdspvec points to logic like that found in figure 9, which is fairly representative for most datapumps 410a.
- the various routines invoked correspond to a typical transmitter structure, such as the block diagram structure of Fig. 11.
- the logic implementing the transmitter functions executes on the host processor, not on a dedicated DSP.
- Figure 11 shows data types below the components as they are used in the host-based modem 334, not traditional DSP datapumps.
- the data types SC- DspDATA and SC_cDspDATA are genericized data types. Integer is a common data type for integer numerical values. (The genericized data types may be implemented with platform-specific macros, for example, exploiting floating point capabilities if it is provided by the host processor 102 or a co-processor (not shown)).
- step 850 the HRT routine then processes a receive baud. This is somewhat analogous to the processing of the transmit baud. For example, 3 samples of data which were read back in step 810 along with all of the other samples are processed at a time, corresponding to one receive baud.
- the HRT routine invokes the logic pointed to by rxdspvec 714e in control structure 710 of the selected data pump 410a.
- the logic pointed to by 714e is represented in Fig. 10, which like the case in Fig. 9, is fairly representative of typical receiver structures. Again, like the case in Fig.
- the actual algorithms implemented by the logic routines of Fig. 10 are datapump specific and are implemented in the host processor 102, not a dedicated DSP.
- the state control logic for the receiver is updated by invoking the logic pointed to by rxvec 714c, which looks at the modem state and the variables in the control structure 710 and modifies the state 714a accordingly.
- step 860 After processing the receive baud, the logic loops back to step 820, where it determines whether more baud need to be processed. If not, the logic proceeds to step 860.
- step 860 the data samples stored in the several iterations of step 840 are written to the transmit FIFO 118t of the ASIC 106.
- the logic then ends in step 899, but is invoked again for the next ASIC interrupt (again, about every 12-12.5 ms).
- the state control logic 714b,c and the dsp logic 714d,e referred to above reside in the datapump 410a.
- the variables 712, 713 used in determining whether more baud need to be processed are also indirectly referenced from the control structure 710.
- the HRT routine may be made datapump independent by referencing the various logic, residing in the datapumps, rather than hardcoding the logic into the HRT image.
- Sending information to the datapump and retrieving information from the datapump is accomplished via the datapump's 410a registered-based interface. This is controlled via the SoftChip control subsystem 440.
- the operation of the modem is summarized as follows.
- the host-based modem 334 is registered with the OS 310 using conventional techniques.
- the central dispatch (CD) 415 is initialized, as are the various other sections of the modem by invoking init routines for each section.
- each subsystem will post necessary callbacks with the SRT and BRT queues as necessary.
- the ASIC 106 is initialized, which will, among other things, cause the ASIC to start initiating hardware interrupts to the host-processor 102 about every 12 to 12.5 ms in steady-state.
- Steady state operation is then initiated with master control causing the two BRT level tasks to start.
- the main task transfers events and messages as necessary.
- the EC task operates when necessary. It is envisioned that in some system states an EC operation may actually take more than one BRT time quanta.
- the modem 334 is then configured using the CM 425 and a default set of values kept in a device control block associated with the host-based modem 334. This includes setting the various modem parameters typically configured in a traditional modem and using conventional techniques.
- the system then operates in an essentially event-driven and interrupt-driven manner, the exact behavior of which depends on the actual commands provided to the modem and the actual data streams encountered.
- the control logic of ACU 430, Master Control 420, and Protocol Processing 435 is analogous to logic used in modern modems, but improved to the event-driven and interrupt-driven structure described above.
- the CD 415 and Soft Chip Control 440 are described above.
- the various datapumps and automode logic in Datapump section 410 use DSP algorithms akin to those used in typical DSPs, but potentially modified for the general purpose host microprocessor 102.
- the digital signal processing algorithms are implemented with macros for genericized DSP functions and data types.
- An exemplary embodiment uses datapumps for V.34, V.32bis, V.32, V.22bis and fax, but is easily extended to others because of the well defined interfaces.
- Each of the datapumps in the SoftChip Datapump sections 410 is designed to be executed on a general purpose microprocessor.
- the instruction set available for the digital signal processing algorithms will not include the hardware do-loops, fractional arithmetic, modulo addressing and other functions typically available with DSPs.
- the various datapumps are designed with source code that will use macros for the conventional DSP instructions. More particularly, a set of defined and generic DSP data types and macros are created that are used by the datapumps code. When compiled, these will become sequences of instructions for the general purpose processor of the host PC 102, not special-purpose DSP instructions and data types.
- Each of the macros is likely to be platform dependent. Thus, while the original source code will not need to change much for various platforms, the macro libraries will.
- the macros for example, may take advantage of floating point capabilities if they're provided by the target processor.
Abstract
Description
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Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA002284277A CA2284277C (en) | 1997-03-21 | 1998-02-24 | Software implementation of modem on computer |
AU63349/98A AU6334998A (en) | 1997-03-21 | 1998-02-24 | A modem implemented in software for operation on a general purpose computer in anon-real-time environment |
EP98907581A EP1012729A4 (en) | 1997-03-21 | 1998-02-24 | A modem implemented in software for operation on a general purpose computer in a non-real-time environment |
BR9808384-8A BR9808384A (en) | 1997-03-21 | 1998-02-24 | Milti-modulation mode modem for operation with a general purpose processor |
HK00105482A HK1026283A1 (en) | 1997-03-21 | 2000-09-01 | A modem implemented in software for operation on a general purpose computer in a non-real-time environment |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/823,304 | 1997-03-21 | ||
US08/823,304 US5925114A (en) | 1997-03-21 | 1997-03-21 | Modem implemented in software for operation on a general purpose computer having operating system with different execution priority levels |
Publications (2)
Publication Number | Publication Date |
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WO1998043401A2 true WO1998043401A2 (en) | 1998-10-01 |
WO1998043401A3 WO1998043401A3 (en) | 1998-11-05 |
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PCT/US1998/003461 WO1998043401A2 (en) | 1997-03-21 | 1998-02-24 | Software implementation of modem on computer |
Country Status (9)
Country | Link |
---|---|
US (1) | US5925114A (en) |
EP (1) | EP1012729A4 (en) |
CN (1) | CN1153149C (en) |
AU (1) | AU6334998A (en) |
BR (1) | BR9808384A (en) |
CA (1) | CA2284277C (en) |
HK (1) | HK1026283A1 (en) |
ID (1) | ID22521A (en) |
WO (1) | WO1998043401A2 (en) |
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EP1045308A2 (en) * | 1999-04-12 | 2000-10-18 | Eaton Corporation | Virtual device driver |
WO2004098139A1 (en) * | 2003-04-30 | 2004-11-11 | Dequn Liang | A multi-modulation transmitting method |
EP3623332B1 (en) | 2018-08-21 | 2022-01-12 | Otis Elevator Company | Elevator data communication system |
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US6353857B2 (en) * | 1997-03-31 | 2002-03-05 | Intel Corporation | Controllerless modem |
JPH1124907A (en) * | 1997-06-27 | 1999-01-29 | Toshiba Corp | Software development supporting method/device |
US6570911B1 (en) * | 1997-06-27 | 2003-05-27 | Intel Corporation | Method and apparatus for controlling modem data pump parameters based on processor loading |
US6252900B1 (en) | 1997-06-30 | 2001-06-26 | Integrated Telecom Express, Inc. | Forward compatible and expandable high speed communications system and method of operation |
US6400759B1 (en) | 1997-06-30 | 2002-06-04 | Integrated Telecom Express, Inc. | Device driver for rate adaptable modem with forward compatible and expandable functionality |
US6792039B1 (en) * | 1997-11-13 | 2004-09-14 | Surf Communication Solutions Ltd. | Method for controlled reducing of processor utilization by a soft modem and a soft modem with controlled different processor utilization modes |
IL132888A0 (en) | 1999-11-11 | 2001-03-19 | Surf Comm Solutions Ltd | Channel load balancing |
US7200168B1 (en) | 1997-11-13 | 2007-04-03 | Surf Communication Solutions Ltd. | Stable operation of media gateway |
US6330597B2 (en) | 1998-03-04 | 2001-12-11 | Conexant Systems, Inc. | Method and apparatus for monitoring, controlling, and configuring remote communication devices |
US6314475B1 (en) | 1998-03-04 | 2001-11-06 | Conexant Systems, Inc. | Method and apparatus for monitoring, controlling and configuring local communication devices |
US6427178B2 (en) * | 1998-03-04 | 2002-07-30 | Conexant Systems, Inc. | Software modem having a multi-task plug-in architecture |
US6408351B1 (en) * | 1998-03-31 | 2002-06-18 | Compaq Computer Corporation | Host modem having a peripheral codec powered by a peripheral bus |
US6557061B1 (en) * | 1998-09-25 | 2003-04-29 | Intel Corporation | Modem instructions sequentially alternating executions between sending a predetermined number of symbols by a transmit sequencer and receiving by a receive sequencer |
US6711206B1 (en) * | 1998-09-25 | 2004-03-23 | Intel Corporation | Modem using a digital signal processor and separate transmit and receive sequencers |
US6490628B2 (en) * | 1998-09-25 | 2002-12-03 | Intel Corporation | Modem using a digital signal processor and a signal based command set |
US6625208B2 (en) * | 1998-09-25 | 2003-09-23 | Intel Corporation | Modem using batch processing of signal samples |
US6374312B1 (en) * | 1998-09-25 | 2002-04-16 | Intel Corporation | System for dedicating a host processor to running one of a plurality of modem programs and dedicating a DSP to running another one of the modem programs |
US6661848B1 (en) | 1998-09-25 | 2003-12-09 | Intel Corporation | Integrated audio and modem device |
US6502138B2 (en) * | 1998-09-25 | 2002-12-31 | Intel Corporation | Modem with code execution adapted to symbol rate |
US6711205B1 (en) | 1998-09-25 | 2004-03-23 | Intel Corporation | Tone detector for use in a modem |
WO2001020456A1 (en) * | 1999-09-10 | 2001-03-22 | Hitachi, Ltd. | Operating system managing system and method |
US7257642B1 (en) | 1999-11-11 | 2007-08-14 | Surp Communication Solutions Ltd. | Channel load balancing |
US7577958B1 (en) * | 1999-12-09 | 2009-08-18 | Nortel Networks Limited | Expediting an operation in a computer system |
FR2803150A1 (en) * | 1999-12-22 | 2001-06-29 | St Microelectronics Sa | Terminal adaptor format ISDN bus/USB bus converter having pin series selective earth/different potential connected indicating adaptor power consumption class. |
US6363426B1 (en) | 2000-01-07 | 2002-03-26 | Dialout.Net, Inc. | System and method of allocating modem resources to software applications |
US20030014484A1 (en) * | 2000-11-09 | 2003-01-16 | Arnon Netzer | Scheduling in a remote-access server |
US6978233B1 (en) * | 2000-03-03 | 2005-12-20 | Unisys Corporation | Method for emulating multi-processor environment |
AU2001241011A1 (en) * | 2000-05-09 | 2001-11-20 | Surf Communication Solutions, Ltd. | Always-on access server pool |
EP1997001A1 (en) * | 2000-07-24 | 2008-12-03 | Infineon Technologies AG | Distributed micro instruction set processor architecture for high-efficiency signal processing |
US6842812B1 (en) * | 2000-11-02 | 2005-01-11 | Intel Corporation | Event handling |
US6842803B2 (en) | 2001-07-09 | 2005-01-11 | Advanced Micro Devices, Inc. | Computer system with privileged-mode modem driver |
US7096353B2 (en) * | 2001-07-09 | 2006-08-22 | Advanced Micro Devices, Inc. | Software modem with privileged mode decryption of control codes |
US7197768B2 (en) | 2001-07-09 | 2007-03-27 | Advanced Micro Devices, Inc. | Software modem for communicating data using encrypted data and unencrypted control codes |
US20050034124A1 (en) * | 2003-03-27 | 2005-02-10 | House Eric Edward | Mechanism for simultaneously operating multiple applications on a personal digital assistant implementing a palm operating system |
US20050180337A1 (en) * | 2004-01-20 | 2005-08-18 | Roemerman Steven D. | Monitoring and reporting system and method of operating the same |
US7424003B2 (en) * | 2004-03-08 | 2008-09-09 | Surf Communication Solutions | Multi-parameter scheduling in communication systems |
WO2012030653A2 (en) | 2010-08-29 | 2012-03-08 | Vascode Technologies Ltd. | A system and methods for multi-tasking in a clientless mobile phone |
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US4085449A (en) * | 1976-11-26 | 1978-04-18 | Paradyne Corporation | Digital modem |
US5408614A (en) * | 1993-12-17 | 1995-04-18 | Xircom, Inc. | Modem adapter for use with standard PC parallel port |
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-
1997
- 1997-03-21 US US08/823,304 patent/US5925114A/en not_active Expired - Lifetime
-
1998
- 1998-02-24 AU AU63349/98A patent/AU6334998A/en not_active Abandoned
- 1998-02-24 CA CA002284277A patent/CA2284277C/en not_active Expired - Lifetime
- 1998-02-24 EP EP98907581A patent/EP1012729A4/en not_active Withdrawn
- 1998-02-24 BR BR9808384-8A patent/BR9808384A/en not_active Application Discontinuation
- 1998-02-24 WO PCT/US1998/003461 patent/WO1998043401A2/en not_active Application Discontinuation
- 1998-02-24 CN CNB988035782A patent/CN1153149C/en not_active Expired - Lifetime
- 1998-02-24 ID IDW991032A patent/ID22521A/en unknown
-
2000
- 2000-09-01 HK HK00105482A patent/HK1026283A1/en not_active IP Right Cessation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US4085449A (en) * | 1976-11-26 | 1978-04-18 | Paradyne Corporation | Digital modem |
US5408614A (en) * | 1993-12-17 | 1995-04-18 | Xircom, Inc. | Modem adapter for use with standard PC parallel port |
Non-Patent Citations (1)
Title |
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See also references of EP1012729A2 * |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1045308A2 (en) * | 1999-04-12 | 2000-10-18 | Eaton Corporation | Virtual device driver |
EP1045308A3 (en) * | 1999-04-12 | 2002-06-05 | Eaton Corporation | Virtual device driver |
US6546434B1 (en) | 1999-04-12 | 2003-04-08 | Eaton Corporation | Virtual device driver |
WO2004098139A1 (en) * | 2003-04-30 | 2004-11-11 | Dequn Liang | A multi-modulation transmitting method |
EP3623332B1 (en) | 2018-08-21 | 2022-01-12 | Otis Elevator Company | Elevator data communication system |
Also Published As
Publication number | Publication date |
---|---|
CA2284277C (en) | 2001-12-25 |
EP1012729A4 (en) | 2004-05-12 |
CA2284277A1 (en) | 1998-10-01 |
ID22521A (en) | 1999-10-28 |
BR9808384A (en) | 2000-06-13 |
CN1153149C (en) | 2004-06-09 |
AU6334998A (en) | 1998-10-20 |
EP1012729A2 (en) | 2000-06-28 |
CN1251184A (en) | 2000-04-19 |
US5925114A (en) | 1999-07-20 |
WO1998043401A3 (en) | 1998-11-05 |
HK1026283A1 (en) | 2000-12-08 |
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