mirror of https://github.com/acidanthera/audk.git
42 lines
1.3 KiB
ArmAsm
42 lines
1.3 KiB
ArmAsm
#------------------------------------------------------------------------------
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#
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# Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
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#
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# This program and the accompanying materials
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# are licensed and made available under the terms and conditions of the BSD License
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# which accompanies this distribution. The full text of the license may be found at
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# http://opensource.org/licenses/bsd-license.php
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#
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# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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#
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#------------------------------------------------------------------------------
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.text
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.align 2
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.globl ASM_PFX(GccSemihostCall)
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INTERWORK_FUNC(GccSemihostCall)
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/*
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Semihosting operation request mechanism
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SVC 0x123456 in ARM state (for all architectures)
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SVC 0xAB in Thumb state (excluding ARMv7-M)
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BKPT 0xAB for ARMv7-M (Thumb-2 only)
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R0 - operation type
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R1 - block containing all other parametes
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lr - must be saved as svc instruction will cause an svc exception and write
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the svc lr register. That happens to be the one we are using, so we must
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save it or we will not be able to return.
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*/
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ASM_PFX(GccSemihostCall):
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stmfd sp!, {lr}
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svc #0x123456
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ldmfd sp!, {lr}
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bx lr
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