user: Converte this assembly snippet into its equivalent C code:

```asm
<next_combo_b>:
  endbr64
  push   %r15
  lea    -0x1(%rdx),%eax
  push   %r14
  push   %r13
  mov    %edi,%r13d
  push   %r12
  push   %rbp
  push   %rbx
  mov    %r9,%rbx
  sub    $0x38,%rsp
  mov    %rsi,0x20(%rsp)
  mov    0x70(%rsp),%esi
  mov    %rcx,0x28(%rsp)
  mov    %r8,0x18(%rsp)
  mov    %eax,0xc(%rsp)
  test   %esi,%esi
  je     L208
  mov    %edx,%ebp
  test   %edi,%edi
  jle    L180
  movslq %edi,%rdx
  xor    %esi,%esi
  mov    %r9,%rdi
  shl    $0x2,%rdx
  call   <memset@plt>
L180:
  test   %ebp,%ebp
  jle    L82
  movslq %ebp,%rdx
  mov    0x18(%rsp),%rdi
  xor    %esi,%esi
  shl    $0x2,%rdx
  call   <memset@plt>
L82:
  mov    $0xffffffff,%r12d
L62:
  lea    -0x1(%r13),%r15d
  nopw   0x0(%rax,%rax,1)
L20:
  cmp    0xc(%rsp),%r12d
  je     L103
L15:
  mov    0x18(%rsp),%rdi
  add    $0x1,%r12d
  movslq %r12d,%rax
  imul   $0x3e8,%rax,%rdx
  lea    (%rdi,%rax,4),%r14
  movl   $0x1,(%r14)
  test   %r13d,%r13d
  jle    L91
  mov    0x20(%rsp),%rsi
  movslq %r13d,%rbp
  xor    %eax,%eax
  lea    (%rsi,%rdx,1),%r8
  nopl   0x0(%rax,%rax,1)
L238:
  mov    (%r8,%rax,4),%edx
  add    %edx,(%rbx,%rax,4)
  add    $0x1,%rax
  cmp    %rax,%rbp
  jne    L238
  mov    0x28(%rsp),%rdi
  xor    %edx,%edx
  mov    %r15d,%ecx
  mov    %rbx,%rsi
  mov    %r8,0x10(%rsp)
  call   <var_check_1@plt>
  mov    0x10(%rsp),%r8
  test   %eax,%eax
  jne    L20
  movl   $0x0,(%r14)
  xor    %eax,%eax
  nopl   0x0(%rax)
L111:
  mov    (%r8,%rax,4),%edx
  sub    %edx,(%rbx,%rax,4)
  add    $0x1,%rax
  cmp    %rax,%rbp
  jne    L111
  cmp    0xc(%rsp),%r12d
  jne    L15
  nopl   0x0(%rax,%rax,1)
L103:
  test   %r13d,%r13d
  jle    L216
  mov    $0x1,%eax
  nopw   0x0(%rax,%rax,1)
L249:
  mov    -0x4(%rbx,%rax,4),%r8d
  cmp    %eax,%r13d
  setg   %cl
  test   %r8d,%r8d
  setne  %dl
  add    $0x1,%rax
  test   %dl,%cl
  jne    L249
  test   %r8d,%r8d
  je     L248
L216:
  mov    $0x1,%r8d
L134:
  add    $0x38,%rsp
  mov    %r8d,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  cs nopw 0x0(%rax,%rax,1)
L248:
  test   %r12d,%r12d
  js     L134
  mov    0x18(%rsp),%rdi
  movslq %r12d,%rax
  lea    (%rdi,%rax,4),%rdx
  jmp    L187
  nopl   0x0(%rax,%rax,1)
L222:
  sub    $0x1,%rax
  sub    $0x4,%rdx
  cmp    $0xffffffff,%eax
  je     L134
L187:
  mov    (%rdx),%r8d
  mov    %eax,%r12d
  test   %r8d,%r8d
  je     L222
  imul   $0x3e8,%rax,%rax
  mov    0x20(%rsp),%rdi
  movl   $0x0,(%rdx)
  movslq %r13d,%rsi
  xor    %edx,%edx
  lea    (%rdi,%rax,1),%rcx
  nopl   0x0(%rax,%rax,1)
L73:
  mov    (%rcx,%rdx,4),%eax
  sub    %eax,(%rbx,%rdx,4)
  add    $0x1,%rdx
  cmp    %rdx,%rsi
  jne    L73
  jmp    L20
  nopl   0x0(%rax)
L91:
  mov    0x28(%rsp),%rdi
  xor    %edx,%edx
  mov    %r15d,%ecx
  mov    %rbx,%rsi
  call   <var_check_1@plt>
  test   %eax,%eax
  jne    L20
  movl   $0x0,(%r14)
  jmp    L20
  xchg   %ax,%ax
L208:
  movslq 0xc(%rsp),%rax
  mov    0x18(%rsp),%rsi
  mov    %eax,%r12d
  lea    (%rsi,%rax,4),%rdx
  test   %eax,%eax
  jns    L133
  jmp    L220
  nopw   0x0(%rax,%rax,1)
L153:
  lea    -0x1(%rax),%r12d
  sub    $0x1,%rax
  sub    $0x4,%rdx
  cmp    $0xffffffff,%eax
  je     L123
L133:
  mov    (%rdx),%ecx
  mov    %eax,%r12d
  test   %ecx,%ecx
  je     L153
L220:
  movl   $0x0,(%rdx)
  imul   $0x3e8,%rax,%rdx
  test   %r13d,%r13d
  jle    L62
  mov    0x20(%rsp),%rdi
  movslq %r13d,%rsi
  xor    %eax,%eax
  lea    (%rdi,%rdx,1),%rcx
  xchg   %ax,%ax
L54:
  mov    (%rcx,%rax,4),%edx
  sub    %edx,(%rbx,%rax,4)
  add    $0x1,%rax
  cmp    %rax,%rsi
  jne    L54
  jmp    L62
L123:
  mov    0x18(%rsp),%rdi
  movslq %r12d,%rax
  lea    (%rdi,%rax,4),%rdx
  jmp    L220
```

assistant: ```c
int next_combo_b(int length, int basis[100][250], int num_basis, int constraints[250], int combo[100], int sum[250], int start_flag) {
  int go, pos, i, success;
  if (start_flag) {
    for (i = 0; i < length; i++)
      sum[i] = 0;
    for (i = 0; i < num_basis; i++)
      combo[i] = 0;
    pos = -1;
  } else {
    pos = num_basis - 1;
    while (pos >= 0 && !combo[pos])
      pos--;
    combo[pos] = 0;
    {
      int j, *p;
      for (j = 0, p = basis[pos]; j < length; j++)
        sum[j] -= p[j];
    };
  }
  success = 0;
  go = 1;
  while (go && !success) {
    if (pos == num_basis - 1) {
      success = 1;
      for (i = 0; i < length && success; i++)
        if (sum[i] == 0)
          success = 0;
      if (!success) {
        while (pos >= 0 && !combo[pos])
          pos--;
        if (pos < 0)
          go = 0;
        else {
          combo[pos] = 0;
          {
            int j, *p;
            for (j = 0, p = basis[pos]; j < length; j++)
              sum[j] -= p[j];
          };
        }
      }
    } else {
      pos++;
      combo[pos] = 1;
      {
        int j, *p;
        for (j = 0, p = basis[pos]; j < length; j++)
          sum[j] += p[j];
      };
      if (!var_check_1(constraints, sum, 0, length - 1)) {
        combo[pos] = 0;
        {
          int j, *p;
          for (j = 0, p = basis[pos]; j < length; j++)
            sum[j] -= p[j];
        };
      }
    }
  }
  return success;
}
```