mirror of
https://github.com/autc04/Retro68.git
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496 lines
12 KiB
ArmAsm
496 lines
12 KiB
ArmAsm
#include "newlib.h"
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#include "arm.h"
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#include "swi.h"
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/* ANSI concatenation macros. */
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#define CONCAT(a, b) CONCAT2(a, b)
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#define CONCAT2(a, b) a ## b
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#ifdef __USER_LABEL_PREFIX__
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#define FUNCTION( name ) CONCAT (__USER_LABEL_PREFIX__, name)
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#else
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#error __USER_LABEL_PREFIX is not defined
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#endif
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#ifdef HAVE_INITFINI_ARRAY
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#define _init __libc_init_array
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#define _fini __libc_fini_array
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#endif
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#if defined(__ARM_EABI__) && defined(__thumb__) && !defined(__thumb2__)
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/* For Thumb1 we need to force the architecture to be sure that we get the
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correct attributes on the object file; otherwise the assembler will get
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confused and mark the object as being v6T2. */
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#if defined(__ARM_ARCH_4T__)
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.arch armv4t
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#elif defined(__ARM_ARCH_5T__) || defined(__ARM_ARCH_5TE__)
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/* Nothing in this object requires higher than v5. */
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.arch armv5t
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#elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) \
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|| defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) \
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|| defined(__ARM_ARCH_6ZK__)
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/* Nothing in this object requires higher than v6. */
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.arch armv6
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#elif defined(__ARM_ARCH_6M__)
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#ifdef ARM_RDP_MONITOR
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/* Object file uses SVC, so mark as v6s-m. */
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.arch armv6s-m
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#else
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.arch armv6-m
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#endif
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#endif
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#endif
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/* .text is used instead of .section .text so it works with arm-aout too. */
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.text
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.syntax unified
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#ifdef THUMB_V7_V6M
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.thumb
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.macro FUNC_START name
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.global \name
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.thumb_func
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\name:
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.endm
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#else
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.code 32
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.macro FUNC_START name
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.global \name
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\name:
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.endm
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#endif
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.macro indirect_call reg
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#ifdef HAVE_CALL_INDIRECT
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blx \reg
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#else
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mov lr, pc
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mov pc, \reg
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#endif
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.endm
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.align 0
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FUNC_START _mainCRTStartup
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FUNC_START _start
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FUNC_START start
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#if defined(__ELF__) && !defined(__USING_SJLJ_EXCEPTIONS__)
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/* Annotation for EABI unwinding tables. */
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.fnstart
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#endif
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/* Start by setting up a stack. */
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#ifdef ARM_RDP_MONITOR
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/* Issue Demon SWI to read stack info. */
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swi SWI_GetEnv /* Returns command line in r0. */
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mov sp,r1 /* and the highest memory address in r1. */
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/* Stack limit is at end of data. */
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/* Allow slop for stack overflow handling and small frames. */
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#ifdef __ARM_ARCH_6M__
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ldr r0, .LC2
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adds r0, #128
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adds r0, #128
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mov sl, r0
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#else
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ldr sl, .LC2
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add sl, sl, #256
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#endif
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#else
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#ifdef ARM_RDI_MONITOR
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/* Issue Angel SWI to read stack info. */
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movs r0, #AngelSWI_Reason_HeapInfo
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adr r1, .LC0 /* Point at ptr to 4 words to receive data. */
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#ifdef THUMB_V7M_V6M
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bkpt AngelSWI
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#elif defined(__thumb2__)
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/* We are in thumb mode for startup on armv7 architectures. */
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AngelSWIAsm AngelSWI
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#else
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/* We are always in ARM mode for startup on pre armv7 archs. */
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AngelSWIAsm AngelSWI_ARM
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#endif
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ldr r0, .LC0 /* Point at values read. */
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ldr r1, [r0, #0]
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cmp r1, #0
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bne .LC32
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/* If the heap base value [r0, #0] is 0 then the heap base is actually
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at the end of program data (i.e. __end__). See:
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http://infocenter.arm.com/help/topic/com.arm.doc.dui0471-/Bacbefaa.html
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for more information. */
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ldr r1, .LC31
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str r1, [r0, #0]
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.LC32:
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ldr r1, [r0, #8]
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ldr r2, [r0, #12]
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/* We skip setting sp/sl if 0 returned from semihosting.
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- According to semihosting docs, if 0 returned from semihosting,
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the system was unable to calculate the real value, so it's ok
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to skip setting sp/sl to 0 here.
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- Considering M-profile processors, We might want to initialize
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sp by the first entry of vector table and return 0 to SYS_HEAPINFO
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semihosting call, which will be skipped here. */
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cmp r1, #0
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beq .LC26
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mov sp, r1
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.LC26:
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cmp r2, #0
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beq .LC27
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/* Allow slop for stack overflow handling and small frames. */
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#ifdef __ARM_ARCH_6M__
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adds r2, #128
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adds r2, #128
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mov sl, r2
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#else
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add sl, r2, #256
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#endif
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.LC27:
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#else
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/* Set up the stack pointer to a fixed value. */
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/* Changes by toralf:
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- Allow linker script to provide stack via __stack symbol - see
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defintion of .Lstack
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- Provide "hooks" that may be used by the application to add
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custom init code - see .Lhwinit and .Lswinit
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- Go through all execution modes and set up stack for each of them.
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Loosely based on init.s from ARM/Motorola example code.
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Note: Mode switch via CPSR is not allowed once in non-privileged
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mode, so we take care not to enter "User" to set up its sp,
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and also skip most operations if already in that mode. */
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ldr r3, .Lstack
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cmp r3, #0
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#ifdef __thumb2__
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it eq
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#endif
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#ifdef __ARM_ARCH_6M__
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bne .LC28
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ldr r3, .LC0
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.LC28:
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#else
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ldreq r3, .LC0
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#endif
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/* Note: This 'mov' is essential when starting in User, and ensures we
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always get *some* sp value for the initial mode, even if we
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have somehow missed it below (in which case it gets the same
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value as FIQ - not ideal, but better than nothing). */
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mov sp, r3
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#ifdef THUMB_V7_V6M
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/* XXX Fill in stack assignments for interrupt modes. */
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#else
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mrs r2, CPSR
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tst r2, #0x0F /* Test mode bits - in User of all are 0. */
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beq .LC23 /* "eq" means r2 AND #0x0F is 0. */
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msr CPSR_c, #0xD1 /* FIRQ mode, interrupts disabled. */
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mov sp, r3
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sub sl, sp, #0x1000 /* This mode also has its own sl (see below). */
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mov r3, sl
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msr CPSR_c, #0xD7 /* Abort mode, interrupts disabled. */
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mov sp, r3
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sub r3, r3, #0x1000
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msr CPSR_c, #0xDB /* Undefined mode, interrupts disabled. */
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mov sp, r3
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sub r3, r3, #0x1000
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msr CPSR_c, #0xD2 /* IRQ mode, interrupts disabled. */
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mov sp, r3
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sub r3, r3, #0x2000
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msr CPSR_c, #0xD3 /* Supervisory mode, interrupts disabled. */
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mov sp, r3
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sub r3, r3, #0x8000 /* Min size 32k. */
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bic r3, r3, #0x00FF /* Align with current 64k block. */
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bic r3, r3, #0xFF00
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str r3, [r3, #-4] /* Move value into user mode sp without */
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ldmdb r3, {sp}^ /* changing modes, via '^' form of ldm. */
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orr r2, r2, #0xC0 /* Back to original mode, presumably SVC, */
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msr CPSR_c, r2 /* with FIQ/IRQ disable bits forced to 1. */
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#endif
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.LC23:
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/* Setup a default stack-limit in-case the code has been
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compiled with "-mapcs-stack-check". Hard-wiring this value
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is not ideal, since there is currently no support for
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checking that the heap and stack have not collided, or that
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this default 64k is enough for the program being executed.
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However, it ensures that this simple crt0 world will not
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immediately cause an overflow event: */
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#ifdef __ARM_ARCH_6M__
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movs r2, #64
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lsls r2, r2, #10
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subs r2, r3, r2
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mov sl, r2
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#else
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sub sl, r3, #64 << 10 /* Still assumes 256bytes below sl. */
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#endif
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#endif
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#endif
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/* Zero the memory in the .bss section. */
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movs a2, #0 /* Second arg: fill value. */
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mov fp, a2 /* Null frame pointer. */
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mov r7, a2 /* Null frame pointer for Thumb. */
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ldr a1, .LC1 /* First arg: start of memory block. */
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ldr a3, .LC2
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subs a3, a3, a1 /* Third arg: length of block. */
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#if defined(__thumb__) && !defined(THUMB_V7_V6M)
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/* Enter Thumb mode... */
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add a4, pc, #1 /* Get the address of the Thumb block. */
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bx a4 /* Go there and start Thumb decoding. */
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.code 16
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.global __change_mode
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.thumb_func
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__change_mode:
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#endif
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bl FUNCTION (memset)
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#if !defined (ARM_RDP_MONITOR) && !defined (ARM_RDI_MONITOR)
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/* Changes by toralf: Taken from libgloss/m68k/crt0.S
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initialize target specific stuff. Only execute these
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functions it they exist. */
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ldr r3, .Lhwinit
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cmp r3, #0
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beq .LC24
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indirect_call r3
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.LC24:
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ldr r3, .Lswinit
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cmp r3, #0
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beq .LC25
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indirect_call r3
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.LC25:
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movs r0, #0 /* No arguments. */
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movs r1, #0 /* No argv either. */
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#else
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/* Need to set up standard file handles. */
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bl FUNCTION (initialise_monitor_handles)
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#ifdef ARM_RDP_MONITOR
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swi SWI_GetEnv /* Sets r0 to point to the command line. */
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movs r1, r0
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#else
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movs r0, #AngelSWI_Reason_GetCmdLine
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adr r1, .LC30 /* Space for command line. */
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#ifdef THUMB_V7M_V6M
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bkpt AngelSWI
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#else
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AngelSWIAsm AngelSWI
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#endif
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ldr r1, .LC30
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#endif
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/* Parse string at r1. */
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movs r0, #0 /* Count of arguments so far. */
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/* Push a NULL argument onto the end of the list. */
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#ifdef __thumb__
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push {r0}
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#else
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stmfd sp!, {r0}
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#endif
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.LC10:
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/* Skip leading blanks. */
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#ifdef __thumb__
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ldrb r3, [r1]
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adds r1, #1
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#else
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ldrb r3, [r1], #1
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#endif
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cmp r3, #0
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beq .LC12
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cmp r3, #' '
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beq .LC10
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/* See whether we are scanning a string. */
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cmp r3, #'\"'
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#ifdef __thumb__
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beq .LC20
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cmp r3, #'\''
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bne .LC21
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.LC20:
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movs r2, r3
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b .LC22
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.LC21:
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movs r2, #' ' /* Terminator type. */
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subs r1, r1, #1 /* Adjust back to point at start char. */
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.LC22:
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#else
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cmpne r3, #'\''
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moveq r2, r3
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movne r2, #' ' /* Terminator type. */
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subne r1, r1, #1 /* Adjust back to point at start char. */
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#endif
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/* Stack a pointer to the current argument. */
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#ifdef __thumb__
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push {r1}
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#else
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stmfd sp!, {r1}
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#endif
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adds r0, r0, #1
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.LC11:
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#ifdef __thumb__
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ldrb r3, [r1]
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adds r1, #1
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#else
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ldrb r3, [r1], #1
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#endif
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cmp r3, #0
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beq .LC12
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cmp r2, r3 /* Reached terminator ? */
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bne .LC11
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movs r2, #0
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subs r3, r1, #1
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strb r2, [r3] /* Terminate the arg string. */
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b .LC10
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.LC12:
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mov r1, sp /* Point at stacked arg pointers. */
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/* We've now got the stacked args in order, reverse them. */
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#ifdef __thumb__
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movs r2, r0
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lsls r2, #2
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add r2, sp
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mov r3, sp
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.LC15: cmp r2, r3
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bls .LC14
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subs r2, #4
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ldr r4, [r2]
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ldr r5, [r3]
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str r5, [r2]
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str r4, [r3]
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adds r3, #4
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b .LC15
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.LC14:
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/* Ensure doubleword stack alignment. */
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mov r4, sp
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movs r5, #7
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bics r4, r5
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mov sp, r4
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#else
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add r2, sp, r0, LSL #2 /* End of args. */
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mov r3, sp /* Start of args. */
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.LC13: cmp r2, r3
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ldrhi r4,[r2, #-4] /* Reverse ends of list. */
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ldrhi r5, [r3]
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strhi r5, [r2, #-4]!
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strhi r4, [r3], #4
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bhi .LC13
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/* Ensure doubleword stack alignment. */
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bic sp, sp, #7
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#endif
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#endif
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#ifdef __USES_INITFINI__
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/* Some arm/elf targets use the .init and .fini sections
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to create constructors and destructors, and for these
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targets we need to call the _init function and arrange
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for _fini to be called at program exit. */
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movs r4, r0
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movs r5, r1
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ldr r0, .Lfini
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bl FUNCTION (atexit)
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bl FUNCTION (_init)
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movs r0, r4
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movs r1, r5
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#endif
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bl FUNCTION (main)
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bl FUNCTION (exit) /* Should not return. */
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#if defined(__thumb__) && !defined(THUMB_V7_V6M)
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/* Come out of Thumb mode. This code should be redundant. */
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mov a4, pc
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bx a4
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.code 32
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.global change_back
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change_back:
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/* Halt the execution. This code should never be executed. */
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/* With no debug monitor, this probably aborts (eventually).
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With a Demon debug monitor, this halts cleanly.
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With an Angel debug monitor, this will report 'Unknown SWI'. */
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swi SWI_Exit
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#endif
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/* For Thumb, constants must be after the code since only
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positive offsets are supported for PC relative addresses. */
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.align 0
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.LC0:
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#ifdef ARM_RDI_MONITOR
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.word HeapBase
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#else
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#ifndef ARM_RDP_MONITOR
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/* Changes by toralf: Provide alternative "stack" variable whose value
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may be defined externally; .Lstack will be used instead of .LC0 if
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it points to a non-0 value. Also set up references to "hooks" that
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may be used by the application to provide additional init code. */
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#ifdef __pe__
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.word 0x800000
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#else
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.word 0x80000 /* Top of RAM on the PIE board. */
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#endif
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.Lstack:
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.word __stack
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.Lhwinit:
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.word FUNCTION (hardware_init_hook)
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.Lswinit:
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.word FUNCTION (software_init_hook)
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/* Set up defaults for the above variables in the form of weak symbols
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- so that application will link correctly, and get value 0 in
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runtime (meaning "ignore setting") for the variables, when the user
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does not provide the symbols. (The linker uses a weak symbol if,
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and only if, a normal version of the same symbol isn't provided
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e.g. by a linker script or another object file). */
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.weak __stack
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.weak FUNCTION (hardware_init_hook)
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.weak FUNCTION (software_init_hook)
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#endif
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#endif
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#if defined(__ELF__) && !defined(__USING_SJLJ_EXCEPTIONS__)
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/* Protect against unhandled exceptions. */
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.cantunwind
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.fnend
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#endif
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.LC1:
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.word __bss_start__
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.LC2:
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.word __bss_end__
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#ifdef __USES_INITFINI__
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.Lfini:
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.word FUNCTION(_fini)
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#endif
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#ifdef ARM_RDI_MONITOR
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.LC30:
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.word CommandLine
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.word 255
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.LC31:
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.word __end__
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/* Workspace for Angel calls. */
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.data
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/* Data returned by monitor SWI. */
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.global __stack_base__
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HeapBase: .word 0
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HeapLimit: .word 0
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__stack_base__: .word 0
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StackLimit: .word 0
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CommandLine: .space 256,0 /* Maximum length of 255 chars handled. */
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#endif
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#ifdef __pe__
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.section .idata$3
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.long 0,0,0,0,0,0,0,0
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#endif
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