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# Copyright 2022 Gabriel Jensen.
# This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
# If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
.globl zap_foreach
zap_foreach:
# rbx: Address of the current element.
# r12: Address of the element after the last input element.
# r13: Size of each input element.
# r14: Address of the function.
# We're gonna use callee-saved registers for storing values so they don't get overwritten with each function call.
# Push the callee-saved registers:
pushq %rbx
pushq %r12
pushq %r13
pushq %r14
# Move registers into place:
movq %rdi,%rbx
movq %rsi,%r13
movq %rcx,%r14
# Get the one-past-the-end address:
movq %rdx,%r12
imulq %r13,%r12 # Calculate the array size in bytes (sz * num). We're using signed multiply because the equivalent using the unsigned instruction would use more instructions.
addq %rbx,%r12
# Iterate through the array:
.loop:
# Check if we have reached the one-past-the-end address:
cmpq %rbx,%r12
je .done
# Call the provided function:
movq %rbx,%rdi # Provide the current address to the function.
call *%r14 # We don't need to save any registers for this as we only use callee-saved registers.
# Continue to the next element:
addq %r13,%rbx
jmp .loop
# Finish:
.done:
# Restore the callee-saved registers:
popq %r14
popq %r13
popq %r12
popq %rbx
ret
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