forked from KolibriOS/kolibrios
44 lines
1.4 KiB
PHP
44 lines
1.4 KiB
PHP
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; ;;
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;; Copyright (C) KolibriOS team 2013-2015. All rights reserved. ;;
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;; Distributed under terms of the GNU General Public License ;;
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;; ;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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$Revision$
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; Memory management for USB structures.
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; Protocol layer uses the common kernel heap malloc/free.
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; Hardware layer has special requirements:
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; * memory blocks should be properly aligned
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; * memory blocks should not cross page boundary
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; Hardware layer allocates fixed-size blocks.
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; Thus, hardware layer uses the system slab allocator.
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; Helper procedure: translate physical address in ecx
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; of some transfer descriptor to linear address.
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; in: eax = address of first page
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proc usb_td_to_virt
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; Traverse all pages used for transfer descriptors, looking for the one
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; with physical address as in ecx.
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@@:
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test eax, eax
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jz .zero
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push eax
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call get_pg_addr
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sub eax, ecx
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jz .found
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cmp eax, -0x1000
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ja .found
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pop eax
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mov eax, [eax+0x1000-4]
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jmp @b
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.found:
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; When found, combine page address from eax with page offset from ecx.
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pop eax
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and ecx, 0xFFF
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add eax, ecx
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.zero:
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ret
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endp
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