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AX = 8103h DX = flags (see #03220) ES:DI -> DMA descriptor structure (see #03221,#03222,#03223)
Return:
CF clear if successful DDS physical address field filled in DDS buffer ID field filled (0000h if no buffer allocated) CF set on error AL = error code (see #03218) DDS region size field filled wth maximum contiguous length in bytes
BUGS: Windows 3.0 does not correctly support automatic remapping or copying in enhanced mode. Windows 3.0 in enhanced mode does not return a correct code on error
Bitfields for VDS flags: Bit(s) Description (Table 03220) 0 reserved (zero) 1 data should be copied into buffer (ignored if 2 set) 2 buffer should not be allocated if region noncontiguous or crosses physical alignment boundary specified by 4-5 3 don't attempt automatic remap 4 region must not cross 64K physical alignment boundary 5 region must not cross 128K physical alignment boundary 6-15 reserved (zero)
Format of DMA descriptor structure (DDS): Offset Size Description (Table 03221) 00h DWORD region size 04h DWORD offset 08h WORD segment/selector 0Ah WORD buffer ID 0Ch DWORD physical address
Format of Extended DMA descriptor structure (EDDS): Offset Size Description (Table 03222) 00h DWORD region size 04h DWORD offset 08h WORD segment/selector 0Ah WORD reserved 0Ch WORD number available 0Eh WORD number used 10h DWORD region 0 physical address 14h DWORD region 0 size in bytes 18h DWORD region 1 physical address 1Ch DWORD region 1 size in bytes. ...
Format of Extended DMA descriptor structure (EDDS) with page table entries: Offset Size Description (Table 03223) 00h DWORD region size 04h DWORD offset 08h WORD segment/selector 0Ah WORD reserved 0Ch WORD number available 0Eh WORD number used 10h DWORD page table entry 0 (same as 80386 page table entry) 14h DWORD page table entry 1. ...
Note: Bits 1-11 of the page table entries should be zero; bit 0 set if page is present and locked
Category: Disk I/O Enhancements - Int 4Bh - V
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