spcm_core.spcm_tools

View Source

 1from ctypes import *
 2
 3# load registers for easier access
 4from .regs import *
 5
 6
 7#
 8# **************************************************************************
 9# pvAllocMemPageAligned: creates a buffer for DMA that's page-aligned 
10# **************************************************************************
11#
12def pvAllocMemPageAligned (qwBytes):
13    dwAlignment = 4096
14    dwMask = dwAlignment - 1
15
16    # allocate non-aligned, slightly larger buffer
17    qwRequiredNonAlignedBytes = qwBytes * sizeof (c_char) + dwMask
18    pvNonAlignedBuf = (c_char * qwRequiredNonAlignedBytes)()
19
20    # get offset of next aligned address in non-aligned buffer
21    misalignment = addressof (pvNonAlignedBuf) & dwMask
22    if misalignment:
23        dwOffset = dwAlignment - misalignment
24    else:
25        dwOffset = 0
26    return(c_char * qwBytes).from_buffer(pvNonAlignedBuf, dwOffset)

def pvAllocMemPageAligned(qwBytes): View Source

13def pvAllocMemPageAligned (qwBytes):
14    dwAlignment = 4096
15    dwMask = dwAlignment - 1
16
17    # allocate non-aligned, slightly larger buffer
18    qwRequiredNonAlignedBytes = qwBytes * sizeof (c_char) + dwMask
19    pvNonAlignedBuf = (c_char * qwRequiredNonAlignedBytes)()
20
21    # get offset of next aligned address in non-aligned buffer
22    misalignment = addressof (pvNonAlignedBuf) & dwMask
23    if misalignment:
24        dwOffset = dwAlignment - misalignment
25    else:
26        dwOffset = 0
27    return(c_char * qwBytes).from_buffer(pvNonAlignedBuf, dwOffset)