将 MIPS 程序集转换为 C
Converting MIPS assembly to C
我正在将 MIPS 转换为 C，我已经坚持了好几天。
我已经开始手动将 MIPS 转换为 C，尽管我已经为此工作了几天，但我在 C 中生成的程序仍然没有 运行 需要，我觉得就像我忽略了一个小错误，非常感谢你的帮助。
我从 toplevel_fnc 开始转换，然后是 subroutine_fnc。
这是 MIPS 代码的一部分。
子程序：
build/program-mips: file format elf32-tradbigmips
Disassembly of section my_text:
00404ed0 <subroutine_fnc>:
404ed0: 27bdffd8 addiu sp,sp,-40
404ed4: afbe0024 sw s8,36(sp)
404ed8: 03a0f025 move s8,sp
404edc: afc40028 sw a0,40(s8)
404ee0: 8fc40028 lw a0,40(s8)
404ee4: 27c20018 addiu v0,s8,24
404ee8: 00402825 move a1,v0
404eec: 24060001 li a2,1
404ef0: 24020fa3 li v0,4003
404ef4: 0000000c syscall
404ef8: afc70008 sw a3,8(s8)
404efc: afc2000c sw v0,12(s8)
404f00: 8fc20008 lw v0,8(s8)
404f04: 00000000 nop
404f08: 14400004 bnez v0,404f1c <subroutine_fnc+0x4c>
404f0c: 00000000 nop
404f10: 8fc2000c lw v0,12(s8)
404f14: 10000002 b 404f20 <subroutine_fnc+0x50>
404f18: 00000000 nop
404f1c: 2402ffff li v0,-1
404f20: afc20010 sw v0,16(s8)
404f24: 8fc20010 lw v0,16(s8)
404f28: 00000000 nop
404f2c: 04410006 bgez v0,404f48 <subroutine_fnc+0x78>
404f30: 00000000 nop
404f34: 24040001 li a0,1
404f38: 24020fa1 li v0,4001
404f3c: 0000000c syscall
404f40: afc70008 sw a3,8(s8)
404f44: afc20014 sw v0,20(s8)
404f48: 8fc20010 lw v0,16(s8)
404f4c: 00000000 nop
404f50: 14400004 bnez v0,404f64 <subroutine_fnc+0x94>
404f54: 00000000 nop
404f58: 00001025 move v0,zero
404f5c: 10000002 b 404f68 <subroutine_fnc+0x98>
404f60: 00000000 nop
404f64: 83c20018 lb v0,24(s8)
404f68: 03c0e825 move sp,s8
404f6c: 8fbe0024 lw s8,36(sp)
404f70: 27bd0028 addiu sp,sp,40
404f74: 03e00008 jr ra
404f78: 00000000 nop
和顶层：
00404f7c <toplevel_fnc>:
404f7c: 27bdffc0 addiu sp,sp,-64
404f80: afbf003c sw ra,60(sp)
404f84: afbe0038 sw s8,56(sp)
404f88: 03a0f025 move s8,sp
404f8c: afc00018 sw zero,24(s8)
404f90: 10000040 b 405094 <toplevel_fnc+0x118>
404f94: 00000000 nop
404f98: 83c30034 lb v1,52(s8)
404f9c: 2402005c li v0,92
404fa0: 14620022 bne v1,v0,40502c <toplevel_fnc+0xb0>
404fa4: 00000000 nop
404fa8: 8fc20018 lw v0,24(s8)
404fac: 00000000 nop
404fb0: 24420001 addiu v0,v0,1
404fb4: afc20018 sw v0,24(s8)
404fb8: 24040001 li a0,1
404fbc: 3c020041 lui v0,0x41
404fc0: 244260e0 addiu v0,v0,24800
404fc4: 00402825 move a1,v0
404fc8: 24060002 li a2,2
404fcc: 24020fa4 li v0,4004
404fd0: 0000000c syscall
404fd4: afc7001c sw a3,28(s8)
404fd8: afc20020 sw v0,32(s8)
404fdc: 8fc2001c lw v0,28(s8)
404fe0: 00000000 nop
404fe4: 14400004 bnez v0,404ff8 <toplevel_fnc+0x7c>
404fe8: 00000000 nop
404fec: 8fc20020 lw v0,32(s8)
404ff0: 10000002 b 404ffc <toplevel_fnc+0x80>
404ff4: 00000000 nop
404ff8: 2402ffff li v0,-1
404ffc: afc20024 sw v0,36(s8)
405000: 8fc20024 lw v0,36(s8)
405004: 00000000 nop
405008: 04410022 bgez v0,405094 <toplevel_fnc+0x118>
40500c: 00000000 nop
405010: 24040001 li a0,1
405014: 24020fa1 li v0,4001
405018: 0000000c syscall
40501c: afc7001c sw a3,28(s8)
405020: afc20028 sw v0,40(s8)
405024: 1000001b b 405094 <toplevel_fnc+0x118>
405028: 00000000 nop
40502c: 24040001 li a0,1
405030: 27c20034 addiu v0,s8,52
405034: 00402825 move a1,v0
405038: 24060001 li a2,1
40503c: 24020fa4 li v0,4004
405040: 0000000c syscall
405044: afc7001c sw a3,28(s8)
405048: afc2002c sw v0,44(s8)
40504c: 8fc2001c lw v0,28(s8)
405050: 00000000 nop
405054: 14400004 bnez v0,405068 <toplevel_fnc+0xec>
405058: 00000000 nop
40505c: 8fc2002c lw v0,44(s8)
405060: 10000002 b 40506c <toplevel_fnc+0xf0>
405064: 00000000 nop
405068: 2402ffff li v0,-1
40506c: afc20024 sw v0,36(s8)
405070: 8fc20024 lw v0,36(s8)
405074: 00000000 nop
405078: 04410006 bgez v0,405094 <toplevel_fnc+0x118>
40507c: 00000000 nop
405080: 24040001 li a0,1
405084: 24020fa1 li v0,4001
405088: 0000000c syscall
40508c: afc7001c sw a3,28(s8)
405090: afc20030 sw v0,48(s8)
405094: 00002025 move a0,zero
405098: 0c1013b4 jal 404ed0 <subroutine_fnc>
40509c: 00000000 nop
4050a0: 00021600 sll v0,v0,0x18
4050a4: 00021603 sra v0,v0,0x18
4050a8: a3c20034 sb v0,52(s8)
4050ac: 83c20034 lb v0,52(s8)
4050b0: 00000000 nop
4050b4: 1c40ffb8 bgtz v0,404f98 <toplevel_fnc+0x1c>
4050b8: 00000000 nop
4050bc: 8fc20018 lw v0,24(s8)
4050c0: 03c0e825 move sp,s8
4050c4: 8fbf003c lw ra,60(sp)
4050c8: 8fbe0038 lw s8,56(sp)
4050cc: 27bd0040 addiu sp,sp,64
4050d0: 03e00008 jr ra
4050d4: 00000000 nop
program data
build/program-mips: file format elf32-tradbigmips
Contents of section my_data:
4160e0 5c5c0000 \..
我用 C 写成：
int toplevel_fnc(void) {
int a = 0;
while(1) {
char c = subroutine_fnc(0);
if (c <= 0) {
return a;
}
if (c == 92) {
a++;
int d = write(1, "\", 2);
if (d < 0) {
exit(1);
}
} else {
int e = write(1, &c, 1);
if (e < 0) {
exit(1);
}
}
}
return a;
}
和
int subroutine_fnc(int a) {
char c;
int b = read(a, &c, 1);
if (b < 0) {
exit(1);
} else if (b == 0) {
return 0;
}
return c;
}
我感到迷茫，在这里问也有点愚蠢，但我觉得我忽略了一个小错误。过去三天我一直在研究这个，但我找不到如何正确地将 MIPS 转换为 C 的解决方案。
拜托，如果有人能帮助我解决我的代码中的错误，我将非常高兴。
谢谢。
- 汇编程序写了两个反斜杠，而C
write(1, "\", 2)写了一个反斜杠和一个NUL，因为\在字符串字面量中只表示一个反斜杠；你是想 write(1, "\\", 2).
- char 是无符号的 - 这造成了另一个偏差，因为在汇编程序的某个地方，一个字节被符号扩展并随后用
bgtz 测试，而在C代码
char c = subroutine_fnc(0);
if (c <= 0)
if 条件仅在 c = 0 时为真。请改用 signed char c …。
我正在将 MIPS 转换为 C，我已经坚持了好几天。
我已经开始手动将 MIPS 转换为 C，尽管我已经为此工作了几天，但我在 C 中生成的程序仍然没有 运行 需要，我觉得就像我忽略了一个小错误，非常感谢你的帮助。
我从 toplevel_fnc 开始转换，然后是 subroutine_fnc。
这是 MIPS 代码的一部分。
子程序：
build/program-mips: file format elf32-tradbigmips
Disassembly of section my_text:
00404ed0 <subroutine_fnc>:
404ed0: 27bdffd8 addiu sp,sp,-40
404ed4: afbe0024 sw s8,36(sp)
404ed8: 03a0f025 move s8,sp
404edc: afc40028 sw a0,40(s8)
404ee0: 8fc40028 lw a0,40(s8)
404ee4: 27c20018 addiu v0,s8,24
404ee8: 00402825 move a1,v0
404eec: 24060001 li a2,1
404ef0: 24020fa3 li v0,4003
404ef4: 0000000c syscall
404ef8: afc70008 sw a3,8(s8)
404efc: afc2000c sw v0,12(s8)
404f00: 8fc20008 lw v0,8(s8)
404f04: 00000000 nop
404f08: 14400004 bnez v0,404f1c <subroutine_fnc+0x4c>
404f0c: 00000000 nop
404f10: 8fc2000c lw v0,12(s8)
404f14: 10000002 b 404f20 <subroutine_fnc+0x50>
404f18: 00000000 nop
404f1c: 2402ffff li v0,-1
404f20: afc20010 sw v0,16(s8)
404f24: 8fc20010 lw v0,16(s8)
404f28: 00000000 nop
404f2c: 04410006 bgez v0,404f48 <subroutine_fnc+0x78>
404f30: 00000000 nop
404f34: 24040001 li a0,1
404f38: 24020fa1 li v0,4001
404f3c: 0000000c syscall
404f40: afc70008 sw a3,8(s8)
404f44: afc20014 sw v0,20(s8)
404f48: 8fc20010 lw v0,16(s8)
404f4c: 00000000 nop
404f50: 14400004 bnez v0,404f64 <subroutine_fnc+0x94>
404f54: 00000000 nop
404f58: 00001025 move v0,zero
404f5c: 10000002 b 404f68 <subroutine_fnc+0x98>
404f60: 00000000 nop
404f64: 83c20018 lb v0,24(s8)
404f68: 03c0e825 move sp,s8
404f6c: 8fbe0024 lw s8,36(sp)
404f70: 27bd0028 addiu sp,sp,40
404f74: 03e00008 jr ra
404f78: 00000000 nop
和顶层：
00404f7c <toplevel_fnc>:
404f7c: 27bdffc0 addiu sp,sp,-64
404f80: afbf003c sw ra,60(sp)
404f84: afbe0038 sw s8,56(sp)
404f88: 03a0f025 move s8,sp
404f8c: afc00018 sw zero,24(s8)
404f90: 10000040 b 405094 <toplevel_fnc+0x118>
404f94: 00000000 nop
404f98: 83c30034 lb v1,52(s8)
404f9c: 2402005c li v0,92
404fa0: 14620022 bne v1,v0,40502c <toplevel_fnc+0xb0>
404fa4: 00000000 nop
404fa8: 8fc20018 lw v0,24(s8)
404fac: 00000000 nop
404fb0: 24420001 addiu v0,v0,1
404fb4: afc20018 sw v0,24(s8)
404fb8: 24040001 li a0,1
404fbc: 3c020041 lui v0,0x41
404fc0: 244260e0 addiu v0,v0,24800
404fc4: 00402825 move a1,v0
404fc8: 24060002 li a2,2
404fcc: 24020fa4 li v0,4004
404fd0: 0000000c syscall
404fd4: afc7001c sw a3,28(s8)
404fd8: afc20020 sw v0,32(s8)
404fdc: 8fc2001c lw v0,28(s8)
404fe0: 00000000 nop
404fe4: 14400004 bnez v0,404ff8 <toplevel_fnc+0x7c>
404fe8: 00000000 nop
404fec: 8fc20020 lw v0,32(s8)
404ff0: 10000002 b 404ffc <toplevel_fnc+0x80>
404ff4: 00000000 nop
404ff8: 2402ffff li v0,-1
404ffc: afc20024 sw v0,36(s8)
405000: 8fc20024 lw v0,36(s8)
405004: 00000000 nop
405008: 04410022 bgez v0,405094 <toplevel_fnc+0x118>
40500c: 00000000 nop
405010: 24040001 li a0,1
405014: 24020fa1 li v0,4001
405018: 0000000c syscall
40501c: afc7001c sw a3,28(s8)
405020: afc20028 sw v0,40(s8)
405024: 1000001b b 405094 <toplevel_fnc+0x118>
405028: 00000000 nop
40502c: 24040001 li a0,1
405030: 27c20034 addiu v0,s8,52
405034: 00402825 move a1,v0
405038: 24060001 li a2,1
40503c: 24020fa4 li v0,4004
405040: 0000000c syscall
405044: afc7001c sw a3,28(s8)
405048: afc2002c sw v0,44(s8)
40504c: 8fc2001c lw v0,28(s8)
405050: 00000000 nop
405054: 14400004 bnez v0,405068 <toplevel_fnc+0xec>
405058: 00000000 nop
40505c: 8fc2002c lw v0,44(s8)
405060: 10000002 b 40506c <toplevel_fnc+0xf0>
405064: 00000000 nop
405068: 2402ffff li v0,-1
40506c: afc20024 sw v0,36(s8)
405070: 8fc20024 lw v0,36(s8)
405074: 00000000 nop
405078: 04410006 bgez v0,405094 <toplevel_fnc+0x118>
40507c: 00000000 nop
405080: 24040001 li a0,1
405084: 24020fa1 li v0,4001
405088: 0000000c syscall
40508c: afc7001c sw a3,28(s8)
405090: afc20030 sw v0,48(s8)
405094: 00002025 move a0,zero
405098: 0c1013b4 jal 404ed0 <subroutine_fnc>
40509c: 00000000 nop
4050a0: 00021600 sll v0,v0,0x18
4050a4: 00021603 sra v0,v0,0x18
4050a8: a3c20034 sb v0,52(s8)
4050ac: 83c20034 lb v0,52(s8)
4050b0: 00000000 nop
4050b4: 1c40ffb8 bgtz v0,404f98 <toplevel_fnc+0x1c>
4050b8: 00000000 nop
4050bc: 8fc20018 lw v0,24(s8)
4050c0: 03c0e825 move sp,s8
4050c4: 8fbf003c lw ra,60(sp)
4050c8: 8fbe0038 lw s8,56(sp)
4050cc: 27bd0040 addiu sp,sp,64
4050d0: 03e00008 jr ra
4050d4: 00000000 nop
program data
build/program-mips: file format elf32-tradbigmips
Contents of section my_data:
4160e0 5c5c0000 \..
我用 C 写成：
int toplevel_fnc(void) {
int a = 0;
while(1) {
char c = subroutine_fnc(0);
if (c <= 0) {
return a;
}
if (c == 92) {
a++;
int d = write(1, "\", 2);
if (d < 0) {
exit(1);
}
} else {
int e = write(1, &c, 1);
if (e < 0) {
exit(1);
}
}
}
return a;
}
和
int subroutine_fnc(int a) {
char c;
int b = read(a, &c, 1);
if (b < 0) {
exit(1);
} else if (b == 0) {
return 0;
}
return c;
}
我感到迷茫，在这里问也有点愚蠢，但我觉得我忽略了一个小错误。过去三天我一直在研究这个，但我找不到如何正确地将 MIPS 转换为 C 的解决方案。
拜托，如果有人能帮助我解决我的代码中的错误，我将非常高兴。
谢谢。
- 汇编程序写了两个反斜杠，而C
write(1, "\", 2)写了一个反斜杠和一个NUL，因为\在字符串字面量中只表示一个反斜杠；你是想write(1, "\\", 2). - char 是无符号的 - 这造成了另一个偏差，因为在汇编程序的某个地方，一个字节被符号扩展并随后用
bgtz测试，而在C代码char c = subroutine_fnc(0); if (c <= 0)if条件仅在 c = 0 时为真。请改用signed char c …。