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# Assembler initialization code for actual execution test.
# This code becomes the start of the execution test program. It is
# responsible for initializing the static data, invoking the C code,
# and returning the result. It is called as though it were a C
# function with an argument of the address of the data segment.
# We need to know the value of _ftext and _fdata at link time, but we
# have no way to actually get that at runtime. This is because when
# this code is compiled with -membedded-pic, the la instruction will
# be turned into an addiu $gp instruction. We work around this by
# storing the information in words in the .data section. We then load
# the values of these words *before* doing the runtime relocation.
.sdata
text_start:
.word _ftext
data_start:
.word _fdata
.globl start
.text
start:
# Grab some space on the stack, just as though we were a real
# function.
addiu $sp,$sp,-8
sw $31,0($sp)
# Save the $gp register, and set it up for our data section.
sw $gp,4($sp)
addu $gp,$4,0x8000 # macro
# The start of the data segment is in $4.
# Get the address of start into $5 in a position independent
# fashion.
.set noreorder
$LF1 = . + 8
bal $LF1
la $5,start-$LF1 # macro
.set reorder
addu $5,$5,$31
# Now get the address of _ftext into $6.
la $6,_ftext-start # macro
addu $6,$6,$5
# Get the value of _ftext used to link into $7.
lw $7,text_start # macro
# Get the value of _fdata used to link into $8.
lw $8,data_start # macro
# Get the address of __runtime_reloc_start into $9.
la $9,__runtime_reloc_start-start # macro
addu $9,$9,$5
# Get the address of __runtime_reloc_stop into $10.
la $10,__runtime_reloc_stop-start # macro
addu $10,$10,$5
# The words between $9 and $10 are the runtime initialization
# instructions. Step through and relocate them. First set
# $11 and $12 to the values to add to text and data sections,
# respectively.
subu $11,$6,$7
subu $12,$4,$8
1:
bge $9,$10,3f # macro
lw $13,0($9)
and $14,$13,0xfffffffe # macro
move $15,$11
beq $13,$14,2f
move $15,$12
2:
addu $14,$14,$4
lw $24,0($14)
addu $24,$24,$15
sw $24,0($14)
addiu $9,$9,4
b 1b
3:
# Now the statically initialized data has been relocated
# correctly, and we can call the C code which does the actual
# testing.
bal foo
# We return the value returned by the C code.
lw $31,0($sp)
lw $gp,4($sp)
addu $sp,$sp,8
j $31
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