ARM Initialization Question

[Sebastian Huber]

Hi,
I am quite new to the ARM architecture and try to develop a BSP for the 
LPC2478.  I have a question to the initialization code (random start.S):

[...]
/* Set up the SVC stack pointer last and stay in SVC mode */
mov     r0, #(PSR_MODE_SVC | PSR_I | PSR_F)     /* No interrupts */
msr     cpsr, r0
ldr     r1, =_svc_stack_size
ldr     sp, =_svc_stack
add     sp, sp, r1
sub     sp, sp, #0x64
[...]

Why is 0x64 subtracted from the stack pointer?

-- 
Sebastian Huber, Embedded Brains GmbH

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