1 files changed, 62 insertions, 0 deletions
diff --git a/PGU/CHAP6_7/read_write.s b/PGU/CHAP6_7/read_write.s
new file mode 100644
index 0000000..d574013
--- /dev/null
+++ b/PGU/CHAP6_7/read_write.s
@@ -0,0 +1,62 @@
+.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