1 files changed, 86 insertions, 0 deletions
diff --git a/PGU/CHAP9/read-records.s b/PGU/CHAP9/read-records.s
new file mode 100644
index 0000000..01384a0
--- /dev/null
+++ b/PGU/CHAP9/read-records.s
@@ -0,0 +1,86 @@
+# Read records previously written in file.dat, by write-records software
+
+.include "linux.s"
+.include "record-def.s"
+
+.section .data
+	filename:
+		.ascii "test.dat\0"
+	record_buffer_ptr:
+		.long 0
+
+.section .text
+
+.globl _start
+
+_start:
+	# Stack locations for INPUT and OUTPUT FDs
+	.equ ST_INPUT_DESCRIPTOR, -8
+	.equ ST_OUTPUT_DESCRIPTOR, -16
+
+	movq %rsp, %rbp
+	subq $16, %rsp	# Save space in the stack for FDs
+
+	call allocate_init	# Initialize our memory
+
+	# allocate buffer
+	pushq $RECORD_SIZE
+	call allocate
+	movq %rax, record_buffer_ptr
+
+	# Open data file
+	movq $SYS_OPEN, %rax
+	movq $filename, %rdi
+	movq $0, %rsi		# Open for read only
+	movq $0666, %rdx
+	syscall
+
+	# Save FD
+	movq %rax, ST_INPUT_DESCRIPTOR(%rbp)
+
+	# Yes, STDOUT is always 1, but if I want to change the output location
+	# later, I don't need to change everywhere...
+	movq $STDOUT, ST_OUTPUT_DESCRIPTOR(%rbp)
+
+record_read_loop:
+	pushq ST_INPUT_DESCRIPTOR(%rbp)
+	pushq record_buffer_ptr
+	call read_record
+	addq $16, %rsp		# Cleanup stack
+
+	# All records are RECORD_SIZE size, if we didn't get this amount of
+	# bytes from read function, we either are at EOF or we hit an error.
+	cmpq $RECORD_SIZE, %rax
+	jne finished_reading
+
+	# We are ok, so print the first name in the record
+	movq record_buffer_ptr, %rax
+	addq $RECORD_FIRSTNAME, %rax	# Seek offset of the firstname in the
+					# buffer
+	pushq %rax
+	call count_chars
+	addq $8, %rsp		# Cleanup stack
+
+	# Write name to OUTPUT
+	movq %rax, %rdx		# Returned record size, used as argument to
+				# write()
+
+	movq record_buffer_ptr, %rsi
+	addq $RECORD_FIRSTNAME, %rsi
+	movq ST_OUTPUT_DESCRIPTOR(%rbp), %rdi
+	movq $SYS_WRITE, %rax
+	syscall
+
+	pushq ST_OUTPUT_DESCRIPTOR(%rbp)
+	call write_newline
+	addq $8, %rsp
+
+	jmp record_read_loop
+
+	# Free buffer
+	pushq record_buffer_ptr
+	call deallocate
+finished_reading:
+	movq $SYS_EXIT, %rax
+	movq $0, %rdi
+	syscall