exec.library/CacheClearE                          exec.library/CacheClearE

NAME
    CacheClearE - Cache clearing with extended control (V37)

SYNOPSIS
    CacheClearE(address,length,caches)
                a0      d0     d1

    void CacheClearE(APTR,ULONG,ULONG);

FUNCTION
    Flush out the contents of the CPU instruction and/or data caches.
    If dirty data cache lines are present, push them to memory first.

    Motorola CPUs have separate instruction and data caches.  A data
    write does not update the instruction cache.  If an instruction is
    written to memory or modified, the old instruction may still exist
    in the cache.  Before attempting to execute the code, a flush of
    the instruction cache is required.

    For most systems, the data cache is not updated by Direct Memory
    Access (DMA), or if some external factor changes shared memory.

    Caches must be cleared after *any* operation that could cause
    invalid or stale data.  The most common cases are DMA and modifying
    instructions using the processor.

    Some examples:
                    Self modifying code
                    Building Jump tables
                    Run-time code patches
                    Relocating code for use at different addresses.
                    Loading code from disk

INPUTS
    address - Address to start the operation.  This may be rounded
              due to hardware granularity.
    length  - Length of area to be cleared, or $FFFFFFFF to indicate all
              addresses should be cleared.
    caches  - Bit flags to indicate what caches to affect.  The current
              supported flags are:
                    CACRF_ClearI    ;Clear instruction cache
                    CACRF_ClearD    ;Clear data cache
              All other bits are reserved for future definition.

NOTES
    On systems with a copyback mode cache, any dirty data is pushed
    to memory as a part of this operation.

    Regardless of the length given, the function will determine the most
    efficient way to implement the operation.  For some cache systems,
    including the 68030, the overhead partially clearing a cache is often
    too great.  The entire cache may be cleared.

    For all current Amiga models, Chip memory is set with Instruction
    caching enabled, data caching disabled.  This prevents coherency
    conflicts with the blitter or other custom chip DMA.  Custom chip
    registers are marked as non-cacheable by the hardware.

    The system takes care of appropriately flushing the caches for normal
    operations.  The instruction cache is cleared by all calls that
    modify instructions, including LoadSeg(), MakeLibrary() and
    SetFunction().

SEE ALSO
    exec/execbase.i, CacheControl, CacheClearU