87 lines
2.5 KiB
NASM
87 lines
2.5 KiB
NASM
;/*
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; Copyright Oliver Kowalke 2009.
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; Distributed under the Boost Software License, Version 1.0.
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; (See accompanying file LICENSE_1_0.txt or copy at
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; http://www.boost.org/LICENSE_1_0.txt)
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;*/
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; *******************************************************
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; * *
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; * ------------------------------------------------- *
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; * | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | *
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; * ------------------------------------------------- *
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; * | 0x0 | 0x4 | 0x8 | 0xc | 0x10| 0x14| 0x18| 0x1c| *
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; * ------------------------------------------------- *
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; * |deall|limit| base|hiddn| v1 | v2 | v3 | v4 | *
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; * ------------------------------------------------- *
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; * ------------------------------------------------- *
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; * | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | *
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; * ------------------------------------------------- *
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; * | 0x20| 0x24| 0x28| 0x2c| 0x30| 0x34| 0x38| 0x3c| *
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; * ------------------------------------------------- *
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; * | v5 | v6 | v7 | v8 | lr | pc | FCTX| DATA| *
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; * ------------------------------------------------- *
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; * *
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; *******************************************************
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AREA |.text|, CODE
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ALIGN 4
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EXPORT ontop_fcontext
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ontop_fcontext PROC
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; save LR as PC
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push {lr}
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; save hidden,V1-V8,LR
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push {a1,v1-v8,lr}
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; load TIB to save/restore thread size and limit.
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; we do not need preserve CPU flag and can use it's arg register
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mrc p15, #0, v1, c13, c0, #2
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; save current stack base
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ldr a1, [v1, #0x04]
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push {a1}
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; save current stack limit
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ldr a1, [v1, #0x08]
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push {a1}
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; save current deallocation stack
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ldr a1, [v1, #0xe0c]
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push {a1}
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; store RSP (pointing to context-data) in A1
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mov a1, sp
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; restore RSP (pointing to context-data) from A2
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mov sp, a2
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; restore stack base
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pop {a1}
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str a1, [v1, #0x04]
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; restore stack limit
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pop {a1}
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str a1, [v1, #0x08]
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; restore deallocation stack
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pop {a1}
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str a1, [v1, #0xe0c]
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; store parent context in A2
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mov a2, a1
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; restore hidden,V1-V8,LR
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pop {a1,v1-v8,lr}
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; return transfer_t from jump
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str a2, [a1, #0]
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str a3, [a1, #4]
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; pass transfer_t as first arg in context function
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; A1 == hidden, A2 == FCTX, A3 == DATA
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; skip PC
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add sp, sp, #4
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; jump to ontop-function
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bx a4
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ENDP
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END
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