TI Santa Barbara - BIOSuite FAQ - DSP/BIOS Kernel API

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DSP/BIOS Kernel API:

HST

1. When is the notify function called for a HST object?

For an input HST channel, the notify function is a notifyReader function. It will be called when full frames are available in the host channel to be read by the target application. For an output channel, the notify function is a notifyWriter function. It will be called when empty frames are available in the host channel to be filled with data by the target application.

MEM

1. Can the data structures required by the DSP/BIOS be placed anywhere within the data space?

Virtually all data in the DSP/BIOS can be moved to any valid data location (on-chip, off-chip,...). The only requirement is that 4 words be reserved in on chip memory (data page 0). These words are used to point to the system data page, hold timer counter registers, and the TRC trace mask. The user can freely place all the other data.

HWI

1. Can Interrupt Service Routine (ISR) code be written and tested in C before writing an optimized assembly version of it?

An ISR can be written in C but a small assembly stub function that saves and restores registers (using then HWI_enter and HWI_exit macros) and calls your C ISR must be written as well. In the Configuration Tool, enter the assembly stub function as a service routine for the corresponding interrupt. An example of how this can be done is provided in the audio example of your product. (Review chapter 6 of you Getting Started Guide and the dss_cisr.c and dss_asm.s## files included in the product distribution).

If the C ISR does not contain any DSP/BIOS APIs that may result in a signal being posted, you do not need to use the HWI_enter/HWI_exit macros. In this case, you can use the compiler's interrupt handling support to write the C ISR. The Configuration Tool will still need to be used to ‘plug in’ the ISR in the corresponding location of the interrupt vector table.

LOG

1. Can a LOG_printf style format string be entered in the 'format' window for an event log using raw data type?

When using 'raw data' display type, you use LOG_event to write to the event log. The data written to the second, third, and fourth words on each event log message can be formatted using conversion characters such as %d, %o, %x. However, enter format strings data = %d, mydata in the Format entry in the appropriate log properties window.

PRD

1. When using the CLK manager to drive PRD, how frequently is PRD_signal posted?

To optimize CPU performance, PRD_signal is not always posted with every PRD_tick. PRD calculates the greatest common denominator of all periodic functions that is a power of 2. If this number is n, PRD_signal will only be posted every n PRD_tick calls by CLK.