fixed some minor issues.

- https://gitee.com/unicornx/riscv-operating-system-mooc/issues/I4QLTP
- https://gitee.com/unicornx/riscv-operating-system-mooc/issues/I4PJTQ
- https://gitee.com/unicornx/riscv-operating-system-mooc/issues/I49VW5

Signed-off-by: Wang Chen <wangchen20@iscas.ac.cn>

code/asm/asm2c/test.s

@@ -20,7 +20,7 @@ stop:
 	nop			# just for demo effect
 
 stack_start:
-	.rept 10
+	.rept 12
 	.word 0
 	.endr
 stack_end:

code/asm/c2asm/test.s

@@ -17,7 +17,7 @@ stop:
 	nop			# just for demo effect
 
 stack_start:
-	.rept 10
+	.rept 12
 	.word 0
 	.endr
 stack_end:

code/asm/cc_leaf/test.s

@@ -1,59 +1,59 @@
-# Calling Convention
-# Demo to create a leaf routine
-#
-# void _start()
-# {
-#     // calling leaf routine
-#     square(3);
-# }
-#
-# int square(int num)
-# {
-#     return num * num;
-# }
-
-	.text			# Define beginning of text section
-	.global	_start		# Define entry _start
-
-_start:
-	la sp, stack_end	# prepare stack for calling functions
-
-	li a0, 3
-	call square
-
-	# the time return here, a0 should stores the result
-stop:
-	j stop			# Infinite loop to stop execution
-
-# int square(int num)
-square:
-	# prologue
-	addi sp, sp, -8
-	sw s0, 0(sp)
-	sw s1, 4(sp)
-
-	# `mul a0, a0, a0` should be fine,
-	# programing as below just to demo we can contine use the stack
-	mv s0, a0
-	mul s1, s0, s0
-	mv a0, s1
-
-	# epilogue
-	lw s0, 0(sp)
-	lw s1, 4(sp)
-	addi sp, sp, 8
-	
-	ret
-
-	# add nop here just for demo in gdb
-	nop
-
-	# allocate stack space
-stack_start:
-	.rept 10
-	.word 0
-	.endr
-stack_end:
-
-	.end			# End of file
-
+# Calling Convention
+# Demo to create a leaf routine
+#
+# void _start()
+# {
+#     // calling leaf routine
+#     square(3);
+# }
+#
+# int square(int num)
+# {
+#     return num * num;
+# }
+
+	.text			# Define beginning of text section
+	.global	_start		# Define entry _start
+
+_start:
+	la sp, stack_end	# prepare stack for calling functions
+
+	li a0, 3
+	call square
+
+	# the time return here, a0 should stores the result
+stop:
+	j stop			# Infinite loop to stop execution
+
+# int square(int num)
+square:
+	# prologue
+	addi sp, sp, -8
+	sw s0, 0(sp)
+	sw s1, 4(sp)
+
+	# `mul a0, a0, a0` should be fine,
+	# programing as below just to demo we can contine use the stack
+	mv s0, a0
+	mul s1, s0, s0
+	mv a0, s1
+
+	# epilogue
+	lw s0, 0(sp)
+	lw s1, 4(sp)
+	addi sp, sp, 8
+
+	ret
+
+	# add nop here just for demo in gdb
+	nop
+
+	# allocate stack space
+stack_start:
+	.rept 12
+	.word 0
+	.endr
+stack_end:
+
+	.end			# End of file
+

code/asm/cc_nested/test.s

@@ -1,99 +1,99 @@
-# Calling Convention
-# Demo how to write nested routines
-#
-# void _start()
-# {
-#     // calling nested routine
-#     aa_bb(3, 4);
-# }
-#
-# int aa_bb(int a, int b)
-# {
-#     return square(a) + square(b);
-# }
-#
-# int square(int num)
-# {
-#     return num * num;
-# }
-
-	.text			# Define beginning of text section
-	.global	_start		# Define entry _start
-
-_start:
-	la sp, stack_end	# prepare stack for calling functions
-
-	# aa_bb(3, 4);
-	li a0, 3
-	li a1, 4
-	call aa_bb 
-
-stop:
-	j stop			# Infinite loop to stop execution
-
-# int aa_bb(int a, int b)
-# return a^2 + b^2
-aa_bb:
-	# prologue
-	addi sp, sp, -16
-	sw s0, 0(sp)
-	sw s1, 4(sp)
-	sw s2, 8(sp)
-	sw ra, 12(sp)
-	
-	# cp and store the input params
-	mv s0, a0
-	mv s1, a1
-
-	# sum will be stored in s2 and is initialized as zero
-	li s2, 0
-
-	mv a0, s0
-	jal square
-	add s2, s2, a0
-	
-	mv a0, s1
-	jal square
-	add s2, s2, a0
-	
-	mv a0, s2
-
-	# epilogue
-	lw s0, 0(sp)
-	lw s1, 4(sp)
-	lw s2, 8(sp)
-	lw ra, 12(sp)
-	addi sp, sp, 16
-	ret
-
-# int square(int num)
-square:
-	# prologue
-	addi sp, sp, -8
-	sw s0, 0(sp)
-	sw s1, 4(sp)
-
-	# `mul a0, a0, a0` should be fine,
-	# programing as below just to demo we can contine use the stack
-	mv s0, a0
-	mul s1, s0, s0
-	mv a0, s1
-
-	# epilogue
-	lw s0, 0(sp)
-	lw s1, 4(sp)
-	addi sp, sp, 8
-	
-	ret
-	
-	# add nop here just for demo in gdb
-	nop
-
-	# allocate stack space
-stack_start:
-	.rept 10
-	.word 0
-	.endr
-stack_end:
-
-	.end			# End of file
+# Calling Convention
+# Demo how to write nested routines
+#
+# void _start()
+# {
+#     // calling nested routine
+#     aa_bb(3, 4);
+# }
+#
+# int aa_bb(int a, int b)
+# {
+#     return square(a) + square(b);
+# }
+#
+# int square(int num)
+# {
+#     return num * num;
+# }
+
+	.text			# Define beginning of text section
+	.global	_start		# Define entry _start
+
+_start:
+	la sp, stack_end	# prepare stack for calling functions
+
+	# aa_bb(3, 4);
+	li a0, 3
+	li a1, 4
+	call aa_bb
+
+stop:
+	j stop			# Infinite loop to stop execution
+
+# int aa_bb(int a, int b)
+# return a^2 + b^2
+aa_bb:
+	# prologue
+	addi sp, sp, -16
+	sw s0, 0(sp)
+	sw s1, 4(sp)
+	sw s2, 8(sp)
+	sw ra, 12(sp)
+
+	# cp and store the input params
+	mv s0, a0
+	mv s1, a1
+
+	# sum will be stored in s2 and is initialized as zero
+	li s2, 0
+
+	mv a0, s0
+	jal square
+	add s2, s2, a0
+
+	mv a0, s1
+	jal square
+	add s2, s2, a0
+
+	mv a0, s2
+
+	# epilogue
+	lw s0, 0(sp)
+	lw s1, 4(sp)
+	lw s2, 8(sp)
+	lw ra, 12(sp)
+	addi sp, sp, 16
+	ret
+
+# int square(int num)
+square:
+	# prologue
+	addi sp, sp, -8
+	sw s0, 0(sp)
+	sw s1, 4(sp)
+
+	# `mul a0, a0, a0` should be fine,
+	# programing as below just to demo we can contine use the stack
+	mv s0, a0
+	mul s1, s0, s0
+	mv a0, s1
+
+	# epilogue
+	lw s0, 0(sp)
+	lw s1, 4(sp)
+	addi sp, sp, 8
+
+	ret
+
+	# add nop here just for demo in gdb
+	nop
+
+	# allocate stack space
+stack_start:
+	.rept 12
+	.word 0
+	.endr
+stack_end:
+
+	.end			# End of file

code/asm/srai/test.s

@@ -1,23 +1,23 @@
-# Shift Right Arithmetic Immediate
-# Format:
-#	SLLI RD, RS1, IMM
-# Description:
-# 	The immediate value determines the number of bits to shift. The contents of
-#	RS1 is shifted right that many bits and the result is placed in RD. The shift
-#	is “arithmetic”, i.e., the sign bit is repeatedly shifted in on the 
-#	most-significant end.
-# Comment:
-#	In C, for signed integer, >> is shift right with arithmetic.
-
-	.text			# Define beginning of text section
-	.global	_start		# Define entry _start
-
-_start:
-#	li x6, 0x80		# x6 = 0b1000-0000
-	li x6, 0x80000000	# x6 = 0b1000-0000-0000-0000-0000-0000-0000-0000
-	srai x5, x6, 4		# x5 = x6 >> 3
-
-stop:
-	j stop			# Infinite loop to stop execution
-
-	.end			# End of file
+# Shift Right Arithmetic Immediate
+# Format:
+#	SRAI RD, RS1, IMM
+# Description:
+# 	The immediate value determines the number of bits to shift. The contents of
+#	RS1 is shifted right that many bits and the result is placed in RD. The shift
+#	is “arithmetic”, i.e., the sign bit is repeatedly shifted in on the
+#	most-significant end.
+# Comment:
+#	In C, for signed integer, >> is shift right with arithmetic.
+
+	.text			# Define beginning of text section
+	.global	_start		# Define entry _start
+
+_start:
+#	li x6, 0x80		# x6 = 0b1000-0000
+	li x6, 0x80000000	# x6 = 0b1000-0000-0000-0000-0000-0000-0000-0000
+	srai x5, x6, 4		# x5 = x6 >> 4
+
+stop:
+	j stop			# Infinite loop to stop execution
+
+	.end			# End of file

code/os/01-helloRVOS/uart.c

@@ -33,7 +33,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0

code/os/02-memanagement/uart.c

@@ -32,7 +32,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0

code/os/03-contextswitch/uart.c

@@ -32,7 +32,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0

code/os/04-multitask/uart.c

@@ -32,7 +32,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0

code/os/05-traps/uart.c

@@ -32,7 +32,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0

code/os/06-interrupts/uart.c

@@ -32,7 +32,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0

code/os/07-hwtimer/uart.c

@@ -32,7 +32,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0

code/os/08-preemptive/uart.c

@@ -32,7 +32,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0

code/os/09-lock/uart.c

@@ -32,7 +32,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0

code/os/10-swtimer/uart.c

@@ -32,7 +32,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0

code/os/11-syscall/uart.c

@@ -32,7 +32,7 @@
 
 /*
  * POWER UP DEFAULTS
- * IER = 0: TX/RX holding register interrupts are bith disabled
+ * IER = 0: TX/RX holding register interrupts are both disabled
  * ISR = 1: no interrupt penting
  * LCR = 0
  * MCR = 0