CloverBootloader/ArmPkg/Library/SemihostLib/Arm/GccSemihost.S
Slice 84f41b2b58 prepare to arm
Signed-off-by: Slice <sergey.slice@gmail.com>
2023-07-04 19:53:11 +03:00

32 lines
904 B
ArmAsm

#------------------------------------------------------------------------------
#
# Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
#
# SPDX-License-Identifier: BSD-2-Clause-Patent
#
#------------------------------------------------------------------------------
#include <AsmMacroIoLib.h>
/*
Semihosting operation request mechanism
SVC 0x123456 in ARM state (for all architectures)
SVC 0xAB in Thumb state (excluding ARMv7-M)
BKPT 0xAB for ARMv7-M (Thumb-2 only)
R0 - operation type
R1 - block containing all other parametes
lr - must be saved as svc instruction will cause an svc exception and write
the svc lr register. That happens to be the one we are using, so we must
save it or we will not be able to return.
*/
ASM_FUNC(GccSemihostCall)
stmfd sp!, {lr}
svc #0x123456
ldmfd sp!, {lr}
bx lr