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//
// Payload launcher stub.
//
.globl _start
.section ".text"
_start:
// First, we'll need to move ourselves _out_ of the target area.
// We'll copy down into the IRAM.
ldr r0, =INTERMEZZO_RELOCATED_ADDRESS
ldr r1, =post_relocation
ldr r2, =intermezzo_end
sub r2, r2, r1
bl copy
// Jump to the start of RAM, which should now contain the post-relocation code.
ldr r0, =INTERMEZZO_RELOCATED_ADDRESS
bx r0
.align 4
post_relocation:
// Next, we'll copy our payload down to the appropriate relocaiton address.
ldr r0, =RELOCATION_TARGET
ldr r1, =PAYLOAD_START_ADDR
ldr r2, =BEFORE_SPRAY_LENGTH
bl copy
ldr r0, =RELOCATION_TARGET
ldr r1, =BEFORE_SPRAY_LENGTH
add r0, r0, r1
ldr r1, =STACK_SPRAY_END
ldr r2, =AFTER_SPRAY_LENGTH
bl copy
// Finally, jump into the relocated target.
ldr r0, =ENTRY_POINT_ADDRESS
bx r0
//
// Simple block copy.
// r0 = destination address
// r1 = source address
// r2 = length in bytes
// Destroys r0-r3.
//
copy:
// Copy the word...
ldr r3, [r1], #4
str r3, [r0], #4
// And continue while we have words left to copy.
subs r2, r2, #4
bne copy
// Once we're done, return.
bx lr