Hardware Timer Configuration for Precise Expiration in Non-Real-Time Systems
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Solution Overview
Problem
In computing devices, particularly in non-real-time environments like Windows NT, existing timers are not guaranteed to expire at a specific time, making them unsuitable for applications requiring precise timing, such as performance and power consumption algorithms, due to hardware abstraction layer limitations that restrict direct access to hardware-specific timers like HPET.
Innovation Solution
A method and system for configuring hardware timers to expire at a specific time, using a combination of hardware-independent and hardware-dependent APIs to validate parameters, register ISRs, and manage timer operations, ensuring timers expire as specified, either once or periodically, with control returned to the application upon expiration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a hardware abstraction layer (HAL) is used to control hardware access, then device driver development becomes easier and hardware configurations are accessible in a similar manner, but applications and device drivers become unaware of hardware-dependent details and cannot directly access hardware timers like HPET that are required for precise timing
Solution Approach 1:
The patent introduces a hardware-dependent API layer that acts as an intermediary between applications and the HAL. This API provides direct access to hardware timers (HPET) while maintaining the HAL's hardware abstraction benefits. The API translates application timer requests into hardware-specific operations, enabling precise timing access without requiring applications to deal with raw hardware details.
2Ease of operation
If standard software timers are used in a non-real-time environment, then the system is easier to operate, but the timers are not guaranteed to expire at a programmed time, making them unsuitable for applications requiring precise timing
Solution Approach 1:
The patent segments the timer system into two distinct layers: a hardware-independent API layer that maintains ease of operation and compatibility with non-real-time environments, and a hardware-dependent API layer that provides access to precise hardware timers (HPET). This segmentation allows applications to use precise hardware timers when needed while maintaining the simplicity of standard software timer interfaces for general-purpose operations.
3Measurement precision
If hardware timers (HPET) are accessed directly by applications, then precise timing is achieved, but the hardware abstraction layer's ability to provide unified hardware access across different platforms is compromised
Solution Approach 1:
The hardware-dependent API is designed to be universal across different hardware platforms. It provides a unified interface that adapts to various hardware timer implementations (HPET, PIT, TSC) while maintaining consistent behavior. The API translates platform-specific hardware operations into a standardized interface, allowing applications to access precise timing functionality regardless of the underlying hardware platform.
Data Source
AI summary
The present invention facilitates access to timers in a computing device. In particular, a timer system facilitates configuring a hardware interrupt timer in a computing device, the timer being guaranteed to expire at a specific time in a non-real-time environment. A calling application passes parameters to a hardware independent application programming interface (API) to the hardware interrupt timer. The hardware independent API validates the parameters and relays them to a hardware dependent API. The hardware dependent API establishes a connection with the timer in accordance with the validated parameters, and executes a service routine associated with the application upon expiration of the timer.