From e2c92bd87fb5ae53544ae673fc84a703723d95ab Mon Sep 17 00:00:00 2001
From: Minh Tien Nguyen <minhtienit99@gmail.com>
Date: Mon, 19 Nov 2018 09:13:45 +0700
Subject: [PATCH] Sua loi thuong khong chinh xac, xu li them ngoai le

---
 KTMT/Assignment/Assignment1.asm | 57 +++++++++++++++++++++++----------
 1 file changed, 40 insertions(+), 17 deletions(-)

diff --git a/KTMT/Assignment/Assignment1.asm b/KTMT/Assignment/Assignment1.asm
index d7347c4..2b0e253 100644
--- a/KTMT/Assignment/Assignment1.asm
+++ b/KTMT/Assignment/Assignment1.asm
@@ -1,19 +1,22 @@
 #Chuong trinh chia 2 so thuc
 #Input:		2 so thuc nhap vao tu ban phim
-#Output:	Thuong cua 2 so thuc da nhap
-#		Trong truong hop so chia bang 0 hoac ket qua bi tran so thi bao loi
-#Han che:	Ket qua tinh toan khong chinh xac tuyet doi
+#Output:	Neu so chia hoac so bi chia khong hop le (NaN)
+#		Trong truong hop so bi chia bang cong/tru vo cuc (Infinity) thi bao loi
+#		Trong truong hop so chia bang 0.0 (hoac -0.0) thi bao loi
+#		Cac truong hop con lai xuat gia tri thuong cua 2 so thuc da nhap (trong tam bieu dien cua kieu float)
+#		Trong truong hop tri tuyet doi cua thuong >= 2^128 thi ket qua la vo cuc (Infinity)
+#		Trong truong hop tri tuyet doi cua thuong <= 2^-127 thi ket qua la 0
 #Khai bao bien:
 	.data
-f1:	.float	1.5	#So thuc thu nhat (So bi chia)
-f2:	.float	2.5	#So thuc thu hai (So chia)
+f1:	.float	0	#So thuc thu nhat (So bi chia)
+f2:	.float	0	#So thuc thu hai (So chia)
 f:	.space	8	#O nho luu ket qua (Thuong cua 2 so)
 
 #Cau nhac lenh:
 in1:	.asciiz	"Nhap vao so bi chia:\n"
 in2:	.asciiz	"Nhap vao so chia:\n"
-err1:	.asciiz	"So chia bang 0!"
-err2:	.asciiz	"Ket qua bi tran so!"
+err:	.asciiz	"So da nhap khong hop le!"
+err2:	.asciiz	"So chia bang 0!"
 out:	.asciiz	"Thuong cua hai so da nhap la:\n"
 
 #Code:
@@ -41,7 +44,15 @@ main:
 	#Load f1, f2 vao $a1, $a2
 	lw	$a1, f1
 	lw	$a2, f2
-	beqz	$a2, error1
+	#Kiem tra 2 so da nhap co hop le hay khong (= NaN)
+	beq	$a1, 0x7FC00000, error
+	beq	$a2, 0x7FC00000, error
+	#Kiem tra so bi chia co bang cong/tru vo cuc (Infinity) hay khong
+	beq	$a1, 0x7F800000, error1
+	beq	$a2, 0xFF800000, error1
+	#Kiem tra so chia co bang 0.0 hoac -0.0 hay khong
+	beqz	$a2, error2
+	beq	$a2, 0x80000000, error2
 	
 #Xu ly bit dau cua f:
 	#Luu bit dau cua f1, f2 vao $t1, $t2
@@ -76,7 +87,7 @@ main:
 	#Thuc hien phep chia $t3 cho $t4
 	#Luu ket qua vao $t2
 	li	$t2, 0
-loop:	ble	$t3, $t4, next
+loop:	blt	$t3, $t4, next
 	addi	$t2, $t2, 1
 	sub	$t3, $t3, $t4
 next:	sll	$t2, $t2, 1
@@ -90,23 +101,23 @@ next:	sll	$t2, $t2, 1
 	addi	$t1, $t1, 23
 	
 #Phat hien loi tran so mu:
-	#Neu $t1 < 0 hoac $t1 > 255 thi xay ra tran so
-	bltz	$t1, error2
-	bgt	$t1, 0xFF, error2
+	#Neu $t1 < 0 hoac $t1 > 255 thi xu li ngoai le
+	bltz	$t1, case2
+	bgt	$t1, 0xFE, case3
 
 #Gop ket qua thanh so thuc hoan chinh (f)
 	#Luu f vao $v0
-	li	$v0, 0x0
+comb:	li	$v0, 0x0
 	or	$v0, $v0, $t0
 	sll	$v0, $v0, 8
 	or	$v0, $v0, $t1
 	sll	$v0, $v0, 23
 	or	$v0, $v0, $t2
 	#Luu f vao bo nho
-	sw	$v0, f
+save:	sw	$v0, f
 	
 #Xuat ket qua ra man hinh
-	la	$a0, out
+output:	la	$a0, out
 	li	$v0, 4
 	syscall
 	lwc1	$f12, f
@@ -118,13 +129,25 @@ exit:	li	$v0, 10
 	syscall
 	
 #Xu ly ngoai le trong chuong trinh
-	#Loi: so chia bang 0
+	#Loi: so nhap khong hop le (NaN)
+error:	la	$a0, err
+	li	$v0, 4
+	syscall
+	j	exit
+	#Loi: so bi chia bang vo cuc
 error1:	la	$a0, err1
 	li	$v0, 4
 	syscall
 	j	exit
-	#Loi: ket qua bi tran so
+	#Loi: so chia bang 0
 error2:	la	$a0, err2
 	li	$v0, 4
 	syscall
 	j	exit
+	#Truong hop tri tuyet doi thuong <= 2^-127
+case2:	li	$v0, 0x0
+	j	save
+	#Truong hop tri tuyet doi thuong >= 2^128
+case3:	li	$t1, 0xFF
+	li	$t2, 0x0
+	j	comb