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| cresample Xilinx SDK Drivers API Documentation

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cresample Documentation

This header file contains identifiers and register-level driver functions (or macros), that can be used to access the Xilinx Chroma Resampler (Cresample) core instance.The Chroma Resampler core converts between chroma sub-sampling formats of 4:4:4, 4:2:2,and 4:2:0. There are a total of six conversions available for the three supported sub-sampling formats. Conversion is achieved using a FIR filter approach. Some conversions require filtering in only the horizontal dimension, only the vertical dimension, or both. Interpolation operations are implemented using a two-phase polyphase FIR filter. Decimation operations are implemented using a low-pass FIR filter to suppress chroma aliasing.

Features of Chroma Resampler core are

- Configurable filters sizes with programmable filter coefficients for high performance applications.
- Replicate or drop pixels.
- Static, predefined, powers-of-two coefficients for low-footprint applications
- Converts between YCbCr: 4:4:4, 4:2:2,and 4:2:0.
- Supports both progressive and interlaced video.

Initialization & Configuration

The device driver enables higher layer software (e.g., an application) to communicate to the Cresample core.

XCresample_CfgInitialize() API is used to initialize the Cresample core. The user needs to first call the XCresample_LookupConfig() API which returns the Configuration structure pointer which is passed as a parameter to the XCresample_CfgInitialize() API.

Interrupts

The driver provides an interrupt handler XCresample_IntrHandler for handling the interrupt from the Cresample core. The users of this driver have to register this handler with the interrupt system and provide the callback functions by using XCresample_SetCallBack API.

Virtual Memory

This driver supports Virtual Memory. The RTOS is responsible for calculating the correct device base address in Virtual Memory space.

Threads

This driver is not thread safe. Any needs for threads or thread mutual exclusion must be satisfied by the layer above this driver.

Asserts

Asserts are used within all Xilinx drivers to enforce constraints on argument values. Asserts can be turned off on a system-wide basis by defining, at compile time, the NDEBUG identifier. By default, asserts are turned on and it is recommended that users leave asserts on during development.

Building the driver

The Cresample driver is composed of several source files. This allows the user to build and link only those parts of the driver that are necessary.*

    MODIFICATION HISTORY:

    Ver   Who     Date     Changes

    2.00a vy      04/24/12 Updated for version 2.00.a
                           Converted from xio.h to xil_io.h, translating
                           basic type, MB cache functions, exceptions and
                           assertion to xil_io format.
    1.00a vy      10/22/10 Initial version
    3.0   adk     19/12/13 Updated as per the New Tcl API's.
    4.0   adk     03/12/14 Changed the file name cresample.h to xcresample.h.
                           Macros of register offsets, bit definitions,
                           ReadReg and WriteReg macros which are the part of
                           xcresample_hw.h.were moved to xcresample_hw.h.
                           Removed file inclusion of Xil_io.h.

                           Removed the following functional macros:
                           CRESAMPLE_Enable, CRESAMPLE_Disable,
                           CRESAMPLE_RegUpdateEnable, CRESAMPLE_RegUpdateDisable,
                           CRESAMPLE_Reset, CRESAMPLE_ClearReset,
                           CRESAMPLe_AutoSyncReset.
                           Defined the following functional macros:
                           XCresample_Enable, XCresample_Disable,
                           XCresample_RegUpdateEnable,XCresample_RegUpdateDisable
                           XCresample_Reset, XCresample_ClearReset,
                           XCresample_SyncReset, XCresample_IntrDisable,
                           XCresample_IntrEnable, XCresample_StatusGetPending
                           XCresample_IntrGetPending, XCresample_IntrClear.
                           Declared following structures:
                           XCresample_Config and XCresample of Chroma Resampler.

                           Defined the following range macros:
                           XCRE_VSIZE_FIRST, XCRE_VSIZE_LAST, XCRE_HSIZE_FIRST,
                           XCRE_HSIZE_FIRST, XCRE_HSIZE_LAST, XCRE_PARITY_ODD,
                           XCRE_PARITY_EVEN, XCRE_COEF_FIRST, XCRE_COEF_LAST,
                           XCRE_OFFSET_DIFF, XCRE_NUM_OF_PHASES, XCRE_NUM_HCOEFS,
                           and XCRE_NUM_VCOEFS.

                           Modifications in the file xcresample_hw.h are:
                           Added the register offsets and bit masks for the
                           registers and added backward compatibility for macros.

                           Modifications in the file xcresample.c are:
                           Changed the filename cresample.c to xcresample.c.
                           The Following functions are removed:
                           clear_coef_values, configure_444_to_422,
                           configure_422_to_444, configure_422_to_420,
                           configure_420_to_422, configure_444_to_420 and
                           configure_420_to_444.
                           Implemented the following functions :
                           StubCallBack, StubErrorCallBack,
                           XCresample_CfgInitialize,
                           XCresample_GetVersion, XCresample_EnableDbgByPass,
                           XCresample_IsDbgByPassEnabled,
                           XCresample_DisableDbgByPass,
                           XCresample_SetDbgTestPattern,
                           XCresample_IsDbgTestPatternEnabled,
                           XCresample_DisableDbgTestPattern
                           XCresample_GetDbgFrameCount,
                           XCresample_GetDbgLineCount,
                           XCresample_GetDbgPixelCount,
                           XCresample_SetActiveSize, XCresample_GetActiveSize,
                           XCresample_SetFieldParity, XCresample_GetFieldParity,
                           XCresample_SetChromaParity,
                           XCresample_GetChromaParity
                           XCresample_SetHCoefs, XCresample_GetHCoefs,
                           XCresample_SetVCoefs, XCresample_GetVCoefs,
                           XCresample_Clear_HCoef_Values, and
                           XCresample_Clear_VCoef_Values.

                           Modifications in the file xcresample_intr.c are:
                           Implemented XCresample_IntrHandler and
                           XCresample_SetCallBack functions.

                           Modifications in the file xcresample_selftest.c are:
                           Implemented XCresample_SelfTest function.

                           Modifications in the file xcresample_sinit.c are:
                           Implemented XCresample_LookupConfig function.
    4.1   ms      01/16/17 Updated the parameter naming from
                           XPAR_CRESAMPLE_NUM_INSTANCES to
                           XPAR_XCRESAMPLE_NUM_INSTANCES to avoid compilation
                           failure for XPAR_CRESAMPLE_NUM_INSTANCES as the
                           tools are generating XPAR_XCRESAMPLE_NUM_INSTANCES
                           in the generated xcresample_g.c for fixing MISRA-C
                           files. This is a fix for CR-966099 based on the
                           update in the tools.
          ms      03/17/17 Added readme.txt file in examples folder for doxygen
                           generation.