user: 请将这段汇编代码片段转换成等效的C代码:

```asm
<dlevmar_trans_mat_mat_mult>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x58,%rsp
  mov    %rdi,0x40(%rsp)
  mov    %rsi,0x8(%rsp)
  mov    %edx,0x24(%rsp)
  mov    %ecx,0x20(%rsp)
  test   %ecx,%ecx
  jle    L57
  mov    0x20(%rsp),%ecx
  xor    %r15d,%r15d
  lea    -0x1(%rcx),%eax
  and    $0xffffffe0,%eax
  add    $0x20,%eax
  mov    %eax,0x48(%rsp)
  mov    %ecx,%eax
  shl    $0x5,%eax
  cltq
  shl    $0x3,%rax
  mov    %rax,0x38(%rsp)
  movslq %ecx,%rax
  mov    %rax,0x10(%rsp)
  lea    0x0(,%rax,8),%rbx
L88:
  mov    0x20(%rsp),%eax
  lea    0x1f(%r15),%r14d
  lea    0x20(%r15),%r13d
  mov    %r13d,0x30(%rsp)
  cmp    %r14d,%eax
  cmovle %eax,%r13d
  xor    %r12d,%r12d
  xor    %ebp,%ebp
L73:
  cmp    %ebp,%r15d
  movslq %ebp,%rax
  mov    %r13d,%edx
  cmovge %r15,%rax
  xor    %ecx,%ecx
  sub    %eax,%edx
  shl    $0x3,%rdx
  cmp    %eax,%r13d
  cmovl  %rcx,%rdx
  mov    0x8(%rsp),%rcx
  add    %r12,%rax
  xor    %esi,%esi
  lea    (%rcx,%rax,8),%rdi
  call   <memset@plt>
  mov    %ebp,%eax
  add    0x10(%rsp),%r12
  lea    0x1(%rbp),%ebp
  cmp    %ebp,0x20(%rsp)
  jne    L73
  mov    %eax,0x34(%rsp)
  mov    0x24(%rsp),%eax
  test   %eax,%eax
  jle    L18
  mov    0x20(%rsp),%eax
  mov    0x30(%rsp),%ebp
  movq   $0x0,0x28(%rsp)
  mov    %rax,0x18(%rsp)
  cmp    %r14d,%eax
  cmovle %eax,%ebp
  xor    %r12d,%r12d
L58:
  mov    0x24(%rsp),%ecx
  lea    0x1f(%r12),%eax
  lea    0x20(%r12),%esi
  mov    0x40(%rsp),%r11
  mov    %esi,0x4c(%rsp)
  cmp    %eax,%ecx
  cmovle %ecx,%esi
  add    0x28(%rsp),%r11
  xor    %r14d,%r14d
  xor    %r13d,%r13d
  nopw   0x0(%rax,%rax,1)
L122:
  mov    %r13d,%eax
  lea    0x0(,%r13,8),%r8
  cmp    %r13d,%r15d
  cmovge %r15d,%eax
  movslq %eax,%r9
  mov    0x8(%rsp),%rax
  lea    (%rax,%r14,8),%r10
  cmp    %r9d,%ebp
  jle    L78
  nopl   0x0(%rax,%rax,1)
L70:
  lea    0x0(,%r9,8),%rcx
  mov    %r11,%rax
  pxor   %xmm1,%xmm1
  mov    %r12d,%edx
  jmp    L29
  nopl   0x0(%rax)
L44:
  mov    %rax,%rdi
  add    $0x1,%edx
  sub    %r8,%rdi
  movsd  (%rdi,%rcx,1),%xmm0
  mulsd  (%rax),%xmm0
  add    %rbx,%rax
  addsd  %xmm0,%xmm1
L29:
  cmp    %esi,%edx
  jl     L44
  addsd  (%r10,%r9,8),%xmm1
  movsd  %xmm1,(%r10,%r9,8)
  add    $0x1,%r9
  cmp    %r9d,%ebp
  jg     L70
L78:
  add    $0x1,%r13
  add    0x10(%rsp),%r14
  add    $0x8,%r11
  cmp    0x18(%rsp),%r13
  jne    L122
  mov    0x38(%rsp),%rcx
  mov    0x4c(%rsp),%r12d
  add    %rcx,0x28(%rsp)
  cmp    %r12d,0x24(%rsp)
  jg     L58
L18:
  movslq 0x30(%rsp),%r15
  cmp    0x48(%rsp),%r15d
  jne    L88
  mov    0x8(%rsp),%rax
  xor    %esi,%esi
  xor    %ecx,%ecx
  mov    %rax,%rdi
  lea    0x8(%rax),%r9
L124:
  mov    %ecx,%eax
  add    $0x8,%rdi
  add    $0x1,%ecx
  add    0x20(%rsp),%esi
  cmp    0x34(%rsp),%eax
  je     L57
  movslq %esi,%r8
  mov    0x8(%rsp),%rdx
  add    %r8,%rax
  lea    (%rdx,%r8,8),%rdx
  lea    (%r9,%rax,8),%r8
  mov    %rdi,%rax
L127:
  movsd  (%rax),%xmm0
  add    $0x8,%rdx
  add    %rbx,%rax
  movsd  %xmm0,-0x8(%rdx)
  cmp    %r8,%rdx
  jne    L127
  jmp    L124
L57:
  add    $0x58,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void dlevmar_trans_mat_mat_mult(double *a, double *b, int n, int m) {
  register int i, j, k, jj, kk;
  register double sum, *bim, *akm;
  const int bsize = 32;
  for (jj = 0; jj < m; jj += bsize) {
    for (i = 0; i < m; ++i) {
      bim = b + i * m;
      for (j = (((jj) >= (i)) ? (jj) : (i)); j < (((jj + bsize) <= (m)) ? (jj + bsize) : (m)); ++j)
        bim[j] = 0.0;
    }
    for (kk = 0; kk < n; kk += bsize) {
      for (i = 0; i < m; ++i) {
        bim = b + i * m;
        for (j = (((jj) >= (i)) ? (jj) : (i)); j < (((jj + bsize) <= (m)) ? (jj + bsize) : (m)); ++j) {
          sum = 0.0;
          for (k = kk; k < (((kk + bsize) <= (n)) ? (kk + bsize) : (n)); ++k) {
            akm = a + k * m;
            sum += akm[i] * akm[j];
          }
          bim[j] += sum;
        }
      }
    }
  }
  for (i = 0; i < m; ++i)
    for (j = 0; j < i; ++j)
      b[i * m + j] = b[j * m + i];
}
```