CS2200 Presentation 2a

1
CS2200Presentation 2a

• Processors
• Part Deux
• Instruction Formats, Calling Conventions,
• etc.

2
Announcements

• Project 1 will be available via WebWork later
  today.
• There is no Homework 1. Project 1 has two
  phases.
• If you can't log on to WebWork
• Read the instructions one more time
• Email me.
• If you just registered we will be adding you to
  WebWork this weekend.

3
Deadlines

• Homeworks and Projects will be due on Mondays at
  115959 p.m.
• There will be no extensions
• Not because were mean
• Because we need time to properly grade projects
• Your cooperation and understanding are appreciated

4
Details

• Web Page
• http//www.cc.gatech.edu/classes/AY2005/cs2200_sum
  mer/
• This lecture is on the web page!
• Newsgroups
• git.cc.class.cs2200.announce
• git.cc.class.cs2200

5
Last time...C

• Expressions
• add, sub, nand, etc.
• Assignment
• Store
• Fetching
• Load
• If, while, for
• BEQ, etc

6
Questions?
7
Instruction Format

• Human Readable
• add s3, s1, a2

8
LC2200-8 Registers
Name
R
Usage
Preserved on Call
zero
0
The constant value 0
n.a.
at
1
Reserved for assembler
n.a.
v0
2
Return value
no
a0-a2
3-5
Arguments
no
t0-t2
6-8
Temporary general purpose registers
no
s0-s2
9-11
Saved general purpose registers
yes
k0
12
Reserved for OS/traps
n.a.
sp
13
Stack pointer
yes
pr
14
Page Register
yes
ra
15
Return address
yes
9
Instruction Format

• Human Readable
• add s0, s1, a2
• (add contents of s1 and a2, place results in
  s0)
• Machine Readable

10
Field NamesR-Type Instruction
rY
rX
op
rZ
name
1
4
4
3
4
bits
op opcode rX register destination
operand rY first register source
operand rZ second register source
operand unused
How many registers?
11
Choices

• Fixed Length Instruction
• Requires different formats
• Can reduce complexity by making different formats
  as constant as possible
• Variable Length Instruction
• Uses less memory
• More common before RISC (CISC)

12
Questions?

• We now continue discussing how HLL's are
  implemented in the instruction set

13
Procedures

• Procedural abstraction
• What is the programmers model?

14
Procedures

• Procedure abstraction
• What is the programmers model?
• What does the compiler have to do?
• Remember functions are not compiled at the same
  time
• A function would like to have most of registers
  available for use

15
Procedures

• Procedure abstraction
• What is the programmers model?
• What does the compiler have to do?
• Remember functions are not compiled at the same
  time
• A function would like to have most of registers
  available for use
• Simple hardware to support procedures?
• One idea...
• Shadow area for processor state?
• Save/restore on call/return

16
Shadow Concept
Primary Processor State
Shadow Processor State
High Speed
ROW
Problems?
17
What do we need?

• Nested modules/Recursion
• Pass values to modules
• Return value(s) from module
• Asynchronous compilation
• Need to do things in a uniform way
• Continue execution after module finishes

18
Procedure Issues

• Hardware instructions to support this model?
• Call/return
• Remember where we are in the program. Why?
• Program counter (PC)
• What should happen on every instruction
  execution?
• Would we need a PC if there were no procedure
  abstraction?
• Jump AND store return address
• Load/store
• Stack
• Push and pop
• Stack pointer (sp)
• Stack frames
• What do we store and restore on call/return?

19

• Software conventions (Why?)
• Reserve some number of registers for parameters,
  return values, and return address
• e.g. LC2200
• 3 for params, 1 for return values, one for return
  address
• JALR ltproc-addr in reggt, ra ra is
  return-addr
• JALR ra, zero Where does this go?
• What if we have more params or return values?
• Registers used in procedures
• Temporary registers
• Caller does not expect value to be preserved upon
  return
• LC2200 t0 to t2
• Saved registers
• Caller does expect value to be preserved on
  return
• LC2200 s0 to s2

20
LC2200-8 Registers
Recall
Name
R
Usage
Preserved on Call
zero
0
The constant value 0
n.a.
at
1
Reserved for assembler
n.a.
v0
2
Return value
no
a0-a2
3-5
Arguments
no
t0-t2
6-8
Temporary general purpose registers
no
s0-s2
9-11
Saved general purpose registers
yes
k0
12
Reserved for OS/traps
n.a.
sp
13
Stack pointer
yes
pr
14
Page Register
yes
ra
15
Return address
yes
21
A Tale of Two Closets
T
S
My Closet
Renters Closet
22
A Tale of Two Closets
T
S
My Closet
Renters Closet
23
A Tale of Two Closets
T
S
My Closet
Renters Closet
24
Questions

• How many closets did we discuss?
• Press 1 for 1
• Press 2 for 2
• etc.

25

• Compiling simple procedures
• Just need to save/restore registers used by
  called procedure
• Who should do this? caller? callee?
• What regs in the LC2200 example?

26
Question

• Caller has values in s1 and t1
• Callee will need (to destroy) s1 and t1 to
  perform its operations.
• Who should save s1?

27
Question

• Caller has values in s1 and t1
• Callee will need (to destroy) s1 and t1 to
  perform its operations.
• Who should save s1?
• Press 1 for Caller
• Press 2 for Callee
• Press 3 for either

28
Question

• Caller has values in s1 and t1
• Callee will need (to destroy) s1 and t1 to
  perform its operations.
• Who should save t1?

29
Question

• Caller has values in s1 and t1
• Callee will need (to destroy) s1 and t1 to
  perform its operations.
• Who should save t1?
• Press 1 for Caller
• Press 2 for Callee
• Press 3 for either

30
Questions?
31
Mips Registers
Name
R
Usage
Preserved on Call
zero
0
The constant value 0
n.a.
at
1
Reserved for assembler
n.a.
v0-v1
2-3
Values for results and expression evaluation
no
a0-a3
4-7
Arguments
no
t0-t7
8-15
Temporaries
no
s0-s7
16-23
Saved
yes
t8-t9
24-25
More temporaries
no
k0-k1
26-27
Reserved for use by operating system
n.a.
gp
28
Global pointer
yes
sp
29
Stack pointer
yes
fp
30
Frame pointer
yes
ra
31
Return address
yes
32
Factorial Again!

• int fact(int n)
• if (n lt 1)
• return 1
• else
• return (n fact(n-1))

33
Factorial Again!

• int fact(int n)
• if (n lt 1)
• return 1
• else
• return (n fact(n-1))

fact n 0
fact n 1
fact n 2
fact n 3
fact n 4
caller fact(4)
34
Factorial Again!

• fact sub sp, sp, 8 adjust stack for 2
• sw ra, 4(sp) save the return addr
• sw a0, 0(sp) save arg n
• slt t0, a0, 1 test for n lt 1
• beq t0, zero, L1 if n gt 1, goto L1
• add v0, zero, 1 return 1
• add sp, sp, 8 pop 2 off stack
• jr ra return to caller
• L1 sub a0, a0, 1 n gt 1 arg gets n-1
• jal fact call fact w/ (n-1)
• lw a0, 0(sp) ret frm jal restr n
• lw ra, 4(sp) restore ret addr
• add sp, sp, 8 adj stk ptr (pop 2)
• mul v0, a0, v0 ret n fact(n-1)
• jr ra return to caller

35
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
0
0
0
0
0
0
0
0
0
Assume that fact(n) is called with a value of n
4 a return address of 1000 And the stack pointer
is as shown
v0
0
0
a0
4
0
t0
0
sp
...
0
ra
1000
0
36
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
0
0
0
0
0
0
0
0
0
v0
0
0
a0
4
0
t0
0
sp
...
0
ra
1000
0
37
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
0
0
0
0
0
0
0
0
v0
0
0
a0
4
0
t0
0
sp
...
0
ra
1000
0
38
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
0
0
0
0
0
0
0
v0
0
0
a0
4
0
t0
0
sp
...
0
ra
1000
0
39
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
0
0
0
0
0
0
0
v0
0
0
lt
a0
4
1
0
t0
0
0
sp
...
0
ra
1000
0
40
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
0
0
0
0
0
0
0
v0
0
0
a0
4
0

t0
0
0
L1
0
sp
...
0
ra
1000
0
41
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
0
0
0
0
0
0
0
v0
0
0
a0
3
0
t0
0
0
sp
...
0
ra
1000
0
42
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
0
0
0
0
0
0
0
v0
0
0
a0
3
0
t0
0
0
sp
...
0
ra
2040
0
43
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
0
0
0
0
0
0
0
v0
0
0
a0
3
0
t0
0
0
sp
...
0
ra
2040
0
44
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
0
0
0
0
0
0
v0
0
0
a0
3
0
t0
0
0
sp
...
0
ra
2040
0
45
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
0
0
0
0
0
v0
0
0
a0
3
0
t0
0
0
sp
...
0
ra
2040
0
46
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
0
0
0
0
0
v0
0
0
lt
a0
3
1
0
t0
0
0
sp
...
0
ra
2040
0
47
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
0
0
0
0
0
v0
0
0
a0
3
0

t0
0
0
L1
0
sp
...
0
ra
2040
0
48
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
0
0
0
0
0
v0
0
0
a0
2
0
t0
0
0
sp
...
0
ra
2040
0
49
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
0
0
0
0
0
v0
0
0
a0
2
0
t0
0
0
sp
...
0
ra
2040
0
50
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
0
0
0
0
0
v0
0
0
a0
2
0
t0
0
0
sp
...
0
ra
2040
0
51
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
0
0
0
0
v0
0
0
a0
2
0
t0
0
0
sp
...
0
ra
2040
0
52
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
0
0
0
v0
0
0
a0
2
0
t0
0
0
sp
...
0
ra
2040
0
53
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
0
0
0
v0
0
0
lt
a0
2
1
0
t0
0
0
sp
...
0
ra
2040
0
54
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
0
0
0
v0
0
0
a0
2
0

t0
0
0
L1
0
sp
...
0
ra
2040
0
55
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
0
0
0
v0
0
0
a0
1
0
t0
0
0
sp
...
0
ra
2040
0
56
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
0
0
0
v0
0
0
a0
1
0
t0
0
0
sp
...
0
ra
2040
0
57
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
0
0
0
v0
0
0
a0
1
0
t0
0
0
sp
...
0
ra
2040
0
58
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
0
0
v0
0
0
a0
1
0
t0
0
0
sp
...
0
ra
2040
0
59
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
0
v0
0
0
a0
1
0
t0
0
0
sp
...
0
ra
2040
0
60
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
0
v0
0
0
lt
a0
1
1
0
t0
0
0
sp
...
0
ra
2040
0
61
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
0
v0
0
0
a0
1
0

t0
0
0
L1
0
sp
...
0
ra
2040
0
62
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
0
v0
0
0
a0
0
0
t0
0
0
sp
...
0
ra
2040
0
63
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
0
v0
0
0
a0
0
0
t0
0
0
sp
...
0
ra
2040
0
64
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
0
v0
0
0
a0
0
0
t0
0
0
sp
...
0
ra
2040
0
65
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
0
0
a0
0
0
t0
0
0
sp
...
0
ra
2040
0
66
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
0
0
a0
0
0
t0
0
0
sp
...
0
ra
2040
0
67
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
0
0
lt
a0
0
1
0
t0
1
0
sp
...
0
ra
2040
0
68
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
0
0
a0
0
0

t0
1
0
0
sp
...
0
ra
2040
0
CONTINUE
69
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
0
0
t0
1
0
sp
...
0
ra
2040
0
70
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
0
0
t0
1
0
sp
...
0
ra
2040
0
71
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
0
0
t0
1
0
sp
...
0
ra
2040
0
72
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
1
0
t0
1
0
sp
...
0
ra
2040
0
73
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
1
0
t0
1
0
sp
...
0
ra
2040
0
74
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
1
0
t0
1
0
sp
...
0
ra
2040
0
75
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
1
0
t0
1
0
sp
...
0
ra
2040
0
76
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
1
0
t0
1
0
sp
...
0
ra
2040
0
77
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
2
0
t0
1
0
sp
...
0
ra
2040
0
78
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
2
0
t0
1
0
sp
...
0
ra
2040
0
79
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
1
0
a0
2
0
t0
1
0
sp
...
0
ra
2040
0
80
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
2
0
a0
2
0
t0
1
0
sp
...
0
ra
2040
0
81
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
2
0
a0
2
0
t0
1
0
sp
...
0
ra
2040
0
82
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
2
0
a0
3
0
t0
1
0
sp
...
0
ra
2040
0
83
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
2
0
a0
3
0
t0
1
0
sp
...
0
ra
2040
0
84
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save the return
addr 2008 sw a0,0(sp) save arg
n 2012 slt t0,a0,1 test for n lt
1 2016 beq t0,zero,L1 if n gt 1, goto
L1 2020 add v0,zero,1 return 1 2024
add sp,sp,8 pop 2 off stack 2028
jr ra return to caller 2032 L1
sub a0,a0,1 n gt 1 arg gets n-1 2036
jal fact call fact w/ (n-1) 2040
lw a0,0(sp) ret frm jal restr n 2044
lw ra,4(sp) restore ret addr 2048
add sp,sp,8 adj stk ptr (pop 2) 2052
mul v0,a0,v0 ret n fact(n-1) 2056
jr ra return to caller
1000
4
2040
3
2040
2
2040
1
2040
v0
2
0
a0
3
0
t0
1
0
sp
...
0
ra
2040
0
85
?
2000 fact sub sp,sp,8 adjust stack for
2 2004 sw ra,4(sp) save t