user: 下面的汇编指令对应的C源代码是什么:

```asm
<process_macros>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x8,%rsp
  mov    %rdi,%rbx
  mov    %rsi,%rbp
  call   <strlen@plt>
  test   %eax,%eax
  je     L82
  mov    %eax,%edx
  mov    $0x0,%eax
  mov    $0x100,%r9d
  mov    $0x0,%r12d
  mov    $0x0,%ecx
  mov    $0x0,%r11d
  mov    $0x2,%r14d
  mov    $0x1,%r15d
  mov    $0x3,%r13d
  mov    $0x5c,%r10d
  jmp    L8
L50:
  mov    %edi,%edx
  mov    %ecx,%edi
  mov    %esi,%ecx
  mov    %r8,%rbx
L132:
  cmp    $0x1,%eax
  je     L361
  jle    L65
  cmp    $0x2,%eax
  jne    L357
  cmp    $0x29,%cl
  je     L55
  cmp    $0x7d,%cl
  je     L55
L357:
  test   %edx,%edx
  je     L238
  test   %r9d,%r9d
  je     L238
L8:
  lea    0x1(%rbx),%r8
  movzbl (%rbx),%esi
  lea    -0x1(%rdx),%edi
  cmp    $0x3,%eax
  je     L202
  cmp    $0x5c,%sil
  jne    L50
  cmp    $0x5c,%cl
  je     L50
  sub    $0x2,%edx
  test   %edi,%edi
  je     L238
  movzbl 0x1(%rbx),%ecx
  lea    0x2(%rbx),%rbx
  mov    %r10d,%edi
  jmp    L132
L65:
  test   %eax,%eax
  jne    L357
  cmp    $0x5c,%dil
  setne  %sil
  cmp    $0x27,%cl
  jne    L259
  test   %sil,%sil
  je     L259
  mov    %r13d,%eax
  mov    $0x27,%ecx
  jmp    L357
L259:
  cmp    $0x24,%cl
  jne    L76
  test   %sil,%sil
  je     L76
  mov    %r15d,%eax
  jmp    L357
L76:
  mov    %cl,0x0(%rbp)
  sub    $0x1,%r9d
  lea    0x1(%rbp),%rbp
  jmp    L357
L361:
  cmp    $0x28,%cl
  je     L53
  cmp    $0x7b,%cl
  je     L53
  movb   $0x24,0x0(%rbp)
  cmp    $0x1,%r9d
  jne    L191
  add    $0x1,%rbp
L101:
  movb   $0x0,-0x1(%rbp)
  jmp    L198
L191:
  mov    %cl,0x1(%rbp)
  sub    $0x2,%r9d
  lea    0x2(%rbp),%rbp
  mov    %r11d,%eax
  jmp    L357
L55:
  mov    %rbx,%rsi
  sub    %r12,%rsi
  sub    $0x1,%esi
  test   %esi,%esi
  jle    L363
  mov    $0x0,%eax
L85:
  add    $0x1,%eax
  cmp    %eax,%esi
  jne    L85
  mov    %r11d,%eax
  jmp    L357
L202:
  cmp    $0x27,%sil
  jne    L334
  cmp    $0x5c,%cl
  je     L334
  mov    %edi,%edx
  mov    %r8,%rbx
  mov    %esi,%ecx
  mov    %r11d,%eax
  jmp    L357
L334:
  mov    %sil,0x0(%rbp)
  sub    $0x1,%r9d
  mov    %edi,%edx
  mov    %r8,%rbx
  mov    %esi,%ecx
  lea    0x1(%rbp),%rbp
  jmp    L357
L53:
  mov    %rbx,%r12
  mov    %r14d,%eax
  jmp    L357
L363:
  mov    %r11d,%eax
  jmp    L357
L238:
  test   %r9d,%r9d
  je     L101
L82:
  movb   $0x0,0x0(%rbp)
L198:
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void process_macros(const char *input, char *output) {
  char c, prev;
  const char *varname_start = NULL;
  int inputcnt = strlen((char *)input);
  int outputcnt = 256;
  int state = 0;
  prev = '\0';
  while (inputcnt && outputcnt) {
    c = *input++;
    inputcnt--;
    if (state != 3) {
      if ((c == '\\') && (prev != '\\')) {
        if (inputcnt-- == 0)
          break;
        prev = c;
        c = *input++;
      }
    }
    switch (state) {
    case 0:
      if ((c == '\'') && (prev != '\\')) {
        state = 3;
        break;
      }
      if ((c == '$') && (prev != '\\')) {
        state++;
      } else {
        *(output++) = c;
        outputcnt--;
      }
      break;
    case 1:
      if (c == '(' || c == '{') {
        state++;
        varname_start = input;
      } else {
        state = 0;
        *(output++) = '$';
        outputcnt--;
        if (outputcnt) {
          *(output++) = c;
          outputcnt--;
        }
      }
      break;
    case 2:
      if (c == ')' || c == '}') {
        int i;
        char envname[256], *envval = 0;
        int envcnt = input - varname_start - 1;
        for (i = 0; i < envcnt; i++) {
          envname[i] = varname_start[i];
        }
        envname[i] = 0;
        if (envval != NULL)
          while ((*envval) && outputcnt) {
            *(output++) = *(envval++);
            outputcnt--;
          }
        state = 0;
      }
      break;
    case 3:
      if ((c == '\'') && (prev != '\\')) {
        state = 0;
      } else {
        *(output++) = c;
        outputcnt--;
      }
      break;
    }
    prev = c;
  }
  if (outputcnt)
    *output = 0;
  else
    *(output - 1) = 0;
}
```