.include "record-def.s"
.include "linux.s"

# Read function
# Reads a record from the file descriptor
# and writes it into the buffer passed

# STACK VARS - Used for both read and write functions. They don't share the
#	       location, but the arguments are passed in the same position
#	       for both, so, no need to create different location vars.

.equ ST_BUFFER, 16 # Ret address is at %rsp+8
.equ ST_FILEDES, 24

.section .text

.globl read_record
.type read_record, @function

read_record:
	pushq %rbp
	movq %rsp, %rbp

	# READ A RECORD
	pushq %rdi
	movq ST_FILEDES(%rbp), %rdi
	movq ST_BUFFER(%rbp), %rsi
	movq $RECORD_SIZE, %rdx
	movq $SYS_READ, %rax
	syscall

	# NOTE: %rax has the return value, which we will give back
	# to our caller

	popq %rdi

	movq %rbp, %rsp
	popq %rbp
	ret

.globl write_record
.type write_record, @function

write_record:
	pushq %rbp
	movq %rsp, %rbp

	# WRITE A RECORD
	pushq %rdi
	movq ST_FILEDES(%rbp), %rdi
	movq ST_BUFFER(%rbp), %rsi
	movq $RECORD_SIZE, %rdx
	movq $SYS_WRITE, %rax
	syscall

	# NOTE: %rax has the return value, which we will give back
	# to our caller
	popq %rdi

	movq %rbp, %rsp
	popq %rbp
	ret