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# Lab2: RISC-V RV32I[MA] emulator with ELF support
###### tags: `Computer Architecture`
## Mutipiler
### Compile
C code
``` =
void main(){
int mul1 = 10000;
int mul2 = -200;
int result = 0 ;
int i ;
for(i=0;i<32;i++)
{
if((mul2 >> i) & 0x1)
result = result + (mul1 << i);
}
printInt(result);
}
void printInt(int result){
volatile char* tx = (volatile char*) 0x40002000;
int dict[9] ={1,10,100,1000,10000,100000,1000000,10000000,100000000};
int mx = 900000000,i,j,isprint=0;
if(result >> 31){
*tx = '-';
result = -result;
}
for(i=8;i>=0;i=i-1){
int print = -1;
for(j=9;j>=1;j--){
if ( result >= mx){
isprint =1;
print = j;
result = result - mx;
}
mx = (j!=1)? (mx - dict[i]):(mx-dict[i-1]);
}
if(print!=-1) *tx = (print+48);
else if (isprint) *tx = 48;
}
}
```
Compile without optimization
```=
.file "test.c"
.option nopic
.text
.align 2
.globl main
.type main, @function
main:
addi sp,sp,-32
sw ra,28(sp)
sw s0,24(sp)
addi s0,sp,32
li a5,8192
addi a5,a5,1808
sw a5,-28(s0)
li a5,-200
sw a5,-32(s0)
sw zero,-20(s0)
sw zero,-24(s0)
j .L2
.L4:
lw a5,-24(s0)
lw a4,-32(s0)
sra a5,a4,a5
andi a5,a5,1
beqz a5,.L3
lw a5,-24(s0)
lw a4,-28(s0)
sll a5,a4,a5
lw a4,-20(s0)
add a5,a4,a5
sw a5,-20(s0)
.L3:
lw a5,-24(s0)
addi a5,a5,1
sw a5,-24(s0)
.L2:
lw a4,-24(s0)
li a5,31
ble a4,a5,.L4
lw a0,-20(s0)
call printInt
nop
lw ra,28(sp)
lw s0,24(sp)
addi sp,sp,32
jr ra
.size main, .-main
.section .rodata
.align 2
.LC0:
.word 1
.word 10
.word 100
.word 1000
.word 10000
.word 100000
.word 1000000
.word 10000000
.word 100000000
.text
.align 2
.globl printInt
.type printInt, @function
printInt:
addi sp,sp,-96
sw s0,92(sp)
addi s0,sp,96
sw a0,-84(s0)
li a5,1073750016
sw a5,-40(s0)
lui a5,%hi(.LC0)
lw t1,%lo(.LC0)(a5)
addi a4,a5,%lo(.LC0)
lw a7,4(a4)
addi a4,a5,%lo(.LC0)
lw a6,8(a4)
addi a4,a5,%lo(.LC0)
lw a0,12(a4)
addi a4,a5,%lo(.LC0)
lw a1,16(a4)
addi a4,a5,%lo(.LC0)
lw a2,20(a4)
addi a4,a5,%lo(.LC0)
lw a3,24(a4)
addi a4,a5,%lo(.LC0)
lw a4,28(a4)
addi a5,a5,%lo(.LC0)
lw a5,32(a5)
sw t1,-76(s0)
sw a7,-72(s0)
sw a6,-68(s0)
sw a0,-64(s0)
sw a1,-60(s0)
sw a2,-56(s0)
sw a3,-52(s0)
sw a4,-48(s0)
sw a5,-44(s0)
li a5,900001792
addi a5,a5,-1792
sw a5,-20(s0)
sw zero,-32(s0)
lw a5,-84(s0)
bgez a5,.L6
lw a5,-40(s0)
li a4,45
sb a4,0(a5)
lw a5,-84(s0)
neg a5,a5
sw a5,-84(s0)
.L6:
li a5,8
sw a5,-24(s0)
j .L7
.L15:
li a5,-1
sw a5,-36(s0)
li a5,9
sw a5,-28(s0)
j .L8
.L12:
lw a4,-84(s0)
lw a5,-20(s0)
blt a4,a5,.L9
li a5,1
sw a5,-32(s0)
lw a5,-28(s0)
sw a5,-36(s0)
lw a4,-84(s0)
lw a5,-20(s0)
sub a5,a4,a5
sw a5,-84(s0)
.L9:
lw a4,-28(s0)
li a5,1
beq a4,a5,.L10
lw a5,-24(s0)
slli a5,a5,2
addi a4,s0,-16
add a5,a4,a5
lw a5,-60(a5)
lw a4,-20(s0)
sub a5,a4,a5
j .L11
.L10:
lw a5,-24(s0)
addi a5,a5,-1
slli a5,a5,2
addi a4,s0,-16
add a5,a4,a5
lw a5,-60(a5)
lw a4,-20(s0)
sub a5,a4,a5
.L11:
sw a5,-20(s0)
lw a5,-28(s0)
addi a5,a5,-1
sw a5,-28(s0)
.L8:
lw a5,-28(s0)
bgtz a5,.L12
lw a4,-36(s0)
li a5,-1
beq a4,a5,.L13
lw a5,-36(s0)
andi a5,a5,0xff
addi a5,a5,48
andi a4,a5,0xff
lw a5,-40(s0)
sb a4,0(a5)
j .L14
.L13:
lw a5,-32(s0)
beqz a5,.L14
lw a5,-40(s0)
li a4,48
sb a4,0(a5)
.L14:
lw a5,-24(s0)
addi a5,a5,-1
sw a5,-24(s0)
.L7:
lw a5,-24(s0)
bgez a5,.L15
nop
lw s0,92(sp)
addi sp,sp,96
jr ra
.size printInt, .-printInt
.ident "GCC: (xPack GNU RISC-V Embedded GCC, 64-bit) 8.2.0"
```
Compile with optimization
```
.file "test.c"
.option nopic
.text
.align 2
.globl printInt
.type printInt, @function
printInt:
lui a5,%hi(.LANCHOR0)
addi a5,a5,%lo(.LANCHOR0)
lw t3,0(a5)
lw t1,4(a5)
lw a7,8(a5)
lw a6,12(a5)
lw a1,16(a5)
lw a2,20(a5)
lw a3,24(a5)
lw a4,28(a5)
lw a5,32(a5)
addi sp,sp,-48
sw t3,12(sp)
sw t1,16(sp)
sw a7,20(sp)
sw a6,24(sp)
sw a1,28(sp)
sw a2,32(sp)
sw a3,36(sp)
sw a4,40(sp)
sw a5,44(sp)
bgez a0,.L2
li a5,1073750016
li a4,45
sb a4,0(a5)
neg a0,a0
.L2:
li a5,900001792
addi a1,sp,12
addi t1,sp,-24
li a6,0
addi a3,a5,-1792
li t4,-1
li t3,1073750016
li t5,48
.L4:
bgt a3,a0,.L18
sub a0,a0,a3
li a2,57
li a7,9
li a6,1
.L6:
lw a4,32(a1)
sub a5,a3,a4
blt a0,a5,.L7
sub a0,a0,a5
li a2,56
li a7,8
li a6,1
.L7:
sub a5,a5,a4
blt a0,a5,.L8
sub a0,a0,a5
li a2,55
li a7,7
li a6,1
.L8:
sub a5,a5,a4
blt a0,a5,.L9
sub a0,a0,a5
li a2,54
li a7,6
li a6,1
.L9:
sub a5,a5,a4
blt a0,a5,.L10
sub a0,a0,a5
li a2,53
li a7,5
li a6,1
.L10:
sub a5,a5,a4
blt a0,a5,.L11
sub a0,a0,a5
li a2,52
li a7,4
li a6,1
.L11:
sub a5,a5,a4
blt a0,a5,.L12
sub a0,a0,a5
li a2,51
li a7,3
li a6,1
.L12:
lw a3,28(a1)
sub a5,a5,a4
sub a4,a5,a4
sub a3,a4,a3
blt a0,a5,.L13
sub a0,a0,a5
ble a4,a0,.L14
li a2,50
li a6,1
.L15:
sb a2,0(t3)
.L3:
addi a1,a1,-4
bne t1,a1,.L4
addi sp,sp,48
jr ra
.L14:
sub a0,a0,a4
li a2,49
li a6,1
j .L15
.L13:
bge a0,a4,.L14
bne a7,t4,.L15
beqz a6,.L3
sb t5,0(t3)
j .L3
.L18:
li a2,47
li a7,-1
j .L6
.size printInt, .-printInt
.section .text.startup,"ax",@progbits
.align 2
.globl main
.type main, @function
main:
li a2,8192
li a5,1
li a0,0
li a6,-200
addi a2,a2,1808
li a1,32
.L29:
sra a4,a6,a5
andi a4,a4,1
sll a3,a2,a5
addi a5,a5,1
beqz a4,.L28
add a0,a0,a3
.L28:
bne a5,a1,.L29
tail printInt
.size main, .-main
.section .rodata
.align 2
.set .LANCHOR0,. + 0
.LC0:
.word 1
.word 10
.word 100
.word 1000
.word 10000
.word 100000
.word 1000000
.word 10000000
.word 100000000
.ident "GCC: (xPack GNU RISC-V Embedded GCC, 64-bit) 8.2.0"
```
### Execute
without compile -O3
And program executes 10000*(-200)
```
./emu-rv32i test
-2000000
>>> Execution time: 66615 ns
>>> Instruction count: 2430 (IPS=36478270)
>>> Jumps: 315 (12.96%) - 191 forwards, 124 backwards
>>> Branching T=226 (65.51%) F=119 (34.49%)
```
with compile -O3
```
./emu-rv32i test
-2000000
>>> Execution time: 20103 ns
>>> Instruction count: 549 (IPS=27309356)
>>> Jumps: 134 (24.41%) - 77 forwards, 57 backwards
>>> Branching T=115 (68.05%) F=54 (31.95%)
```
### GNU-TOOL
**objdump**
Compile with -O3
```
$ riscv-none-embed-objdump -d test
test: file format elf32-littleriscv
Disassembly of section .text:
00000100 <_start>:
100: 00000093 li ra,0
104: 00000113 li sp,0
108: 00000193 li gp,0
10c: 00000213 li tp,0
110: 00000293 li t0,0
114: 00000313 li t1,0
118: 00000393 li t2,0
11c: 00000413 li s0,0
120: 00000493 li s1,0
124: 00000513 li a0,0
128: 00000593 li a1,0
12c: 00000613 li a2,0
130: 00000693 li a3,0
134: 00000713 li a4,0
138: 00000793 li a5,0
13c: 00000813 li a6,0
140: 00000893 li a7,0
144: 00000913 li s2,0
148: 00000993 li s3,0
14c: 00000a13 li s4,0
150: 00000a93 li s5,0
154: 00000b13 li s6,0
158: 00000b93 li s7,0
15c: 00000c13 li s8,0
160: 00000c93 li s9,0
164: 00000d13 li s10,0
168: 00000d93 li s11,0
16c: 00000e13 li t3,0
170: 00000e93 li t4,0
174: 00000f13 li t5,0
178: 00000f93 li t6,0
0000017c <init_stack>:
17c: 00001117 auipc sp,0x1
180: 28810113 addi sp,sp,648 # 1404 <__stack>
00000184 <SystemInit>:
184: 00c000ef jal ra,190 <main>
188: 0040006f j 18c <SystemExit>
0000018c <SystemExit>:
18c: 00000073 ecall
00000190 <main>:
190: fe010113 addi sp,sp,-32
194: 00112e23 sw ra,28(sp)
198: 00812c23 sw s0,24(sp)
19c: 02010413 addi s0,sp,32
1a0: 000027b7 lui a5,0x2
1a4: 71078793 addi a5,a5,1808 # 2710 <__stack+0x130c>
1a8: fef42223 sw a5,-28(s0)
1ac: f3800793 li a5,-200
1b0: fef42023 sw a5,-32(s0)
1b4: fe042623 sw zero,-20(s0)
1b8: fe042423 sw zero,-24(s0)
1bc: 03c0006f j 1f8 <main+0x68>
1c0: fe842783 lw a5,-24(s0)
1c4: fe042703 lw a4,-32(s0)
1c8: 40f757b3 sra a5,a4,a5
1cc: 0017f793 andi a5,a5,1
1d0: 00078e63 beqz a5,1ec <main+0x5c>
1d4: fe842783 lw a5,-24(s0)
1d8: fe442703 lw a4,-28(s0)
1dc: 00f717b3 sll a5,a4,a5
1e0: fec42703 lw a4,-20(s0)
1e4: 00f707b3 add a5,a4,a5
1e8: fef42623 sw a5,-20(s0)
1ec: fe842783 lw a5,-24(s0)
1f0: 00178793 addi a5,a5,1
1f4: fef42423 sw a5,-24(s0)
1f8: fe842703 lw a4,-24(s0)
1fc: 01f00793 li a5,31
200: fce7d0e3 bge a5,a4,1c0 <main+0x30>
204: fec42503 lw a0,-20(s0)
208: 018000ef jal ra,220 <printInt>
20c: 00000013 nop
210: 01c12083 lw ra,28(sp)
214: 01812403 lw s0,24(sp)
218: 02010113 addi sp,sp,32
21c: 00008067 ret
00000220 <printInt>:
220: fa010113 addi sp,sp,-96
224: 04812e23 sw s0,92(sp)
228: 06010413 addi s0,sp,96
22c: faa42623 sw a0,-84(s0)
230: 400027b7 lui a5,0x40002
234: fcf42c23 sw a5,-40(s0)
238: 3e002303 lw t1,992(zero) # 3e0 <printInt+0x1c0>
23c: 3e000713 li a4,992
240: 00472883 lw a7,4(a4)
244: 3e000713 li a4,992
248: 00872803 lw a6,8(a4)
24c: 3e000713 li a4,992
250: 00c72503 lw a0,12(a4)
254: 3e000713 li a4,992
258: 01072583 lw a1,16(a4)
25c: 3e000713 li a4,992
260: 01472603 lw a2,20(a4)
264: 3e000713 li a4,992
268: 01872683 lw a3,24(a4)
26c: 3e000713 li a4,992
270: 01c72703 lw a4,28(a4)
274: 3e000793 li a5,992
278: 0207a783 lw a5,32(a5) # 40002020 <__stack+0x40000c1c>
27c: fa642a23 sw t1,-76(s0)
280: fb142c23 sw a7,-72(s0)
284: fb042e23 sw a6,-68(s0)
288: fca42023 sw a0,-64(s0)
28c: fcb42223 sw a1,-60(s0)
290: fcc42423 sw a2,-56(s0)
294: fcd42623 sw a3,-52(s0)
298: fce42823 sw a4,-48(s0)
29c: fcf42a23 sw a5,-44(s0)
2a0: 35a4f7b7 lui a5,0x35a4f
2a4: 90078793 addi a5,a5,-1792 # 35a4e900 <__stack+0x35a4d4fc>
2a8: fef42623 sw a5,-20(s0)
2ac: fe042023 sw zero,-32(s0)
2b0: fac42783 lw a5,-84(s0)
2b4: 0007de63 bgez a5,2d0 <printInt+0xb0>
2b8: fd842783 lw a5,-40(s0)
2bc: 02d00713 li a4,45
2c0: 00e78023 sb a4,0(a5)
2c4: fac42783 lw a5,-84(s0)
2c8: 40f007b3 neg a5,a5
2cc: faf42623 sw a5,-84(s0)
2d0: 00800793 li a5,8
2d4: fef42423 sw a5,-24(s0)
2d8: 0f00006f j 3c8 <printInt+0x1a8>
2dc: fff00793 li a5,-1
2e0: fcf42e23 sw a5,-36(s0)
2e4: 00900793 li a5,9
2e8: fef42223 sw a5,-28(s0)
2ec: 08c0006f j 378 <printInt+0x158>
2f0: fac42703 lw a4,-84(s0)
2f4: fec42783 lw a5,-20(s0)
2f8: 02f74263 blt a4,a5,31c <printInt+0xfc>
2fc: 00100793 li a5,1
300: fef42023 sw a5,-32(s0)
304: fe442783 lw a5,-28(s0)
308: fcf42e23 sw a5,-36(s0)
30c: fac42703 lw a4,-84(s0)
310: fec42783 lw a5,-20(s0)
314: 40f707b3 sub a5,a4,a5
318: faf42623 sw a5,-84(s0)
31c: fe442703 lw a4,-28(s0)
320: 00100793 li a5,1
324: 02f70263 beq a4,a5,348 <printInt+0x128>
328: fe842783 lw a5,-24(s0)
32c: 00279793 slli a5,a5,0x2
330: ff040713 addi a4,s0,-16
334: 00f707b3 add a5,a4,a5
338: fc47a783 lw a5,-60(a5)
33c: fec42703 lw a4,-20(s0)
340: 40f707b3 sub a5,a4,a5
344: 0240006f j 368 <printInt+0x148>
348: fe842783 lw a5,-24(s0)
34c: fff78793 addi a5,a5,-1
350: 00279793 slli a5,a5,0x2
354: ff040713 addi a4,s0,-16
358: 00f707b3 add a5,a4,a5
35c: fc47a783 lw a5,-60(a5)
360: fec42703 lw a4,-20(s0)
364: 40f707b3 sub a5,a4,a5
368: fef42623 sw a5,-20(s0)
36c: fe442783 lw a5,-28(s0)
370: fff78793 addi a5,a5,-1
374: fef42223 sw a5,-28(s0)
378: fe442783 lw a5,-28(s0)
37c: f6f04ae3 bgtz a5,2f0 <printInt+0xd0>
380: fdc42703 lw a4,-36(s0)
384: fff00793 li a5,-1
388: 02f70063 beq a4,a5,3a8 <printInt+0x188>
38c: fdc42783 lw a5,-36(s0)
390: 0ff7f793 andi a5,a5,255
394: 03078793 addi a5,a5,48
398: 0ff7f713 andi a4,a5,255
39c: fd842783 lw a5,-40(s0)
3a0: 00e78023 sb a4,0(a5)
3a4: 0180006f j 3bc <printInt+0x19c>
3a8: fe042783 lw a5,-32(s0)
3ac: 00078863 beqz a5,3bc <printInt+0x19c>
3b0: fd842783 lw a5,-40(s0)
3b4: 03000713 li a4,48
3b8: 00e78023 sb a4,0(a5)
3bc: fe842783 lw a5,-24(s0)
3c0: fff78793 addi a5,a5,-1
3c4: fef42423 sw a5,-24(s0)
3c8: fe842783 lw a5,-24(s0)
3cc: f007d8e3 bgez a5,2dc <printInt+0xbc>
3d0: 00000013 nop
3d4: 05c12403 lw s0,92(sp)
3d8: 06010113 addi sp,sp,96
3dc: 00008067 ret
```
**readelf**
```
$ riscv-none-embed-readelf -h test
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: RISC-V
Version: 0x1
Entry point address: 0x100
Start of program headers: 52 (bytes into file)
Start of section headers: 1584 (bytes into file)
Flags: 0x0
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
Number of program headers: 1
Size of section headers: 40 (bytes)
Number of section headers: 9
Section header string table index: 8
```
**size**
```
$ riscv-none-embed-size test
text data bss dec hex filename
772 0 4096 4868 1304 test
```
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