user: What is the c source code of the assembly code below?

```asm
<rmatmult_3_at>:
  endbr64
  push   %r15
  mov    %edx,%r9d
  mov    $0xfffffffffffffff8,%rdx
  mov    %r8d,%r11d
  push   %r14
  mov    %rdx,%r10
  push   %r13
  mov    %rdi,%r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0xb8,%rsp
  movslq 0x100(%rsp),%rsi
  movslq 0xf8(%rsp),%rcx
  mov    %r8d,0xc(%rsp)
  mov    0x108(%rsp),%rbx
  mov    0x110(%rsp),%rbp
  lea    0x0(,%rsi,8),%rdi
  lea    0x0(,%rcx,8),%r15
  mov    0x118(%rsp),%r12
  mov    0x1d8(%rsp),%r14
  lea    (%rdi,%r15,1),%rax
  mov    %rdi,0x20(%rsp)
  mov    %rax,%r8
  sub    %rax,%r10
  mov    %rax,0x60(%rsp)
  mov    $0x8,%eax
  sub    %r8,%rax
  mov    %r10,0x28(%rsp)
  mov    %rax,0x50(%rsp)
  mov    %rdx,%rax
  sub    %rdi,%rax
  mov    %rax,0x38(%rsp)
  mov    %rcx,%rax
  sub    %rsi,%rax
  mov    %rax,%r8
  shl    $0x3,%rax
  mov    %rax,%rdi
  mov    %rax,0x40(%rsp)
  mov    %rdx,%rax
  sub    %r15,%rax
  sub    %rdi,%rdx
  lea    (%rsi,%rcx,1),%rdi
  mov    %rax,0x48(%rsp)
  mov    %rsi,%rax
  mov    %rdx,0x68(%rsp)
  sub    %rcx,%rax
  lea    0x0(,%rdi,8),%rdx
  cmpl   $0x2,0xf0(%rsp)
  mov    %rdx,0x58(%rsp)
  jle    L34
  mov    %rax,%r10
  cmp    $0x2,%r11d
  jle    L34
  cmp    $0x2,%r9d
  jle    L34
  mov    0x100(%rsp),%eax
  movl   $0x2,0x18(%rsp)
  add    %eax,%eax
  mov    %eax,0x1c(%rsp)
  mov    0xf8(%rsp),%eax
  add    %eax,%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    %rax,0x30(%rsp)
  add    $0x1,%rax
  mov    %rdx,%r11
  sub    0x20(%rsp),%r11
  sub    %r15,%rdx
  mov    %r11,0xb0(%rsp)
  mov    %rax,%r11
  mov    0x30(%rsp),%rax
  mov    %rdx,0xa8(%rsp)
  sub    %rsi,%r11
  mov    %rax,%rdx
  add    %rax,%r8
  sub    %rcx,%rax
  mov    %r11,0xa0(%rsp)
  add    $0x1,%rax
  add    %rdx,%rcx
  add    %rdx,%rsi
  add    %rdx,%rdi
  mov    %rax,0x90(%rsp)
  mov    %r10,%rax
  mov    0x28(%rsp),%r10
  add    %rdx,%rax
  mov    %r8,0x98(%rsp)
  mov    0x120(%rsp),%r11
  mov    %rax,0x80(%rsp)
  lea    (%r14,%r10,1),%rax
  mov    0x128(%rsp),%r10
  mov    %rax,0x10(%rsp)
  movslq %r9d,%rax
  mov    %rcx,0x88(%rsp)
  mov    %rsi,0x78(%rsp)
  mov    %rdi,0x70(%rsp)
  mov    %rax,-0x8(%rsp)
  nopl   (%rax)
L42:
  movslq 0x1c(%rsp),%rcx
  mov    0x30(%rsp),%rax
  add    %rcx,%rax
  lea    0x0(,%rcx,8),%rsi
  lea    0x0(,%rax,8),%rdx
  mov    0x28(%rsp),%rax
  add    %rdx,%rax
  add    %r14,%rax
  mov    %rax,-0x78(%rsp)
  mov    %rdx,%rax
  sub    0x60(%rsp),%rax
  add    %r14,%rax
  mov    %rax,-0x10(%rsp)
  mov    0x50(%rsp),%rax
  add    %rdx,%rax
  add    %r14,%rax
  mov    %rax,-0x18(%rsp)
  mov    0x38(%rsp),%rax
  add    %rdx,%rax
  add    %r14,%rax
  mov    %rax,-0x20(%rsp)
  mov    0xb0(%rsp),%rax
  add    %rsi,%rax
  add    %r14,%rax
  mov    %rax,-0x28(%rsp)
  mov    0xa0(%rsp),%rax
  add    %rcx,%rax
  lea    (%r14,%rax,8),%rax
  mov    %rax,-0x30(%rsp)
  mov    0x40(%rsp),%rax
  add    %rdx,%rax
  add    %r14,%rax
  mov    %rax,-0x38(%rsp)
  mov    0x98(%rsp),%rax
  add    %rcx,%rax
  lea    (%r14,%rax,8),%r9
  mov    0x48(%rsp),%rax
  add    %rdx,%rax
  add    %r14,%rax
  mov    %rax,-0x40(%rsp)
  mov    0xa8(%rsp),%rax
  add    %rsi,%rax
  add    %r14,%rax
  mov    %rax,-0x48(%rsp)
  mov    0x90(%rsp),%rax
  add    %rcx,%rax
  lea    (%r14,%rax,8),%rax
  mov    %rax,-0x50(%rsp)
  lea    (%r15,%rdx,1),%rax
  add    %r14,%rax
  mov    %rax,-0x58(%rsp)
  mov    0x88(%rsp),%rax
  add    %rcx,%rax
  lea    (%r14,%rax,8),%r8
  mov    0x68(%rsp),%rax
  add    %rdx,%rax
  add    %r14,%rax
  mov    %rax,-0x60(%rsp)
  mov    0x80(%rsp),%rax
  add    %rcx,%rax
  lea    (%r14,%rax,8),%rdi
  mov    0x20(%rsp),%rax
  add    %rdx,%rax
  add    %r14,%rax
  mov    %rax,-0x68(%rsp)
  mov    0x78(%rsp),%rax
  add    %rcx,%rax
  lea    (%r14,%rax,8),%rsi
  mov    0x58(%rsp),%rax
  add    %rdx,%rax
  add    %r14,%rax
  mov    %rax,-0x70(%rsp)
  mov    0x70(%rsp),%rax
  movl   $0x2,0x8(%rsp)
  add    %rcx,%rax
  lea    (%r14,%rax,8),%rcx
  nopl   0x0(%rax)
L35:
  mov    %r15,(%rsp)
  mov    -0x78(%rsp),%rax
  mov    $0x2,%edx
  sub    0x10(%rsp),%rax
  nopl   0x0(%rax,%rax,1)
L13:
  mov    -0x78(%rsp),%r15
  movsd  0x10(%r13,%rax,1),%xmm0
  movsd  0x10(%rbx,%rax,1),%xmm1
  mulsd  (%r15,%rdx,8),%xmm0
  mov    -0x10(%rsp),%r15
  mulsd  (%r15,%rdx,8),%xmm1
  mov    -0x18(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%rbp,%rax,1),%xmm1
  mulsd  (%r15,%rdx,8),%xmm1
  mov    -0x20(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r12,%rax,1),%xmm1
  mulsd  (%r15,%rdx,8),%xmm1
  mov    -0x28(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r11,%rax,1),%xmm1
  mulsd  (%r15,%rdx,8),%xmm1
  mov    -0x30(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r10,%rax,1),%xmm1
  mulsd  (%r15,%rdx,8),%xmm1
  mov    0x130(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mov    -0x38(%rsp),%r15
  mulsd  -0x8(%r15,%rdx,8),%xmm1
  mov    0x138(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  (%r9,%rdx,8),%xmm1
  mov    0x140(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  0x8(%r9,%rdx,8),%xmm1
  mov    0x148(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mov    -0x40(%rsp),%r15
  mulsd  (%r15,%rdx,8),%xmm1
  mov    0x150(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mov    -0x48(%rsp),%r15
  mulsd  (%r15,%rdx,8),%xmm1
  mov    0x158(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mov    -0x50(%rsp),%r15
  mulsd  (%r15,%rdx,8),%xmm1
  mov    0x160(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  0x8(%r14,%rax,1),%xmm1
  mov    0x168(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  0x10(%r14,%rax,1),%xmm1
  mov    0x170(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  0x18(%r14,%rax,1),%xmm1
  mov    0x178(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mov    -0x58(%rsp),%r15
  mulsd  -0x8(%r15,%rdx,8),%xmm1
  mov    0x180(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  (%r8,%rdx,8),%xmm1
  mov    0x188(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  0x8(%r8,%rdx,8),%xmm1
  mov    0x190(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mov    -0x60(%rsp),%r15
  mulsd  (%r15,%rdx,8),%xmm1
  mov    0x198(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  (%rdi,%rdx,8),%xmm1
  mov    0x1a0(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  0x8(%rdi,%rdx,8),%xmm1
  mov    0x1a8(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mov    -0x68(%rsp),%r15
  mulsd  -0x8(%r15,%rdx,8),%xmm1
  mov    0x1b0(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  (%rsi,%rdx,8),%xmm1
  mov    0x1b8(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  0x8(%rsi,%rdx,8),%xmm1
  mov    0x1c0(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mov    -0x70(%rsp),%r15
  mulsd  -0x8(%r15,%rdx,8),%xmm1
  mov    0x1c8(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  (%rcx,%rdx,8),%xmm1
  mov    0x1d0(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  0x10(%r15,%rax,1),%xmm1
  mulsd  0x8(%rcx,%rdx,8),%xmm1
  add    $0x1,%rdx
  mov    0x1e0(%rsp),%r15
  addsd  %xmm1,%xmm0
  movsd  %xmm0,0x10(%r15,%rax,1)
  add    $0x8,%rax
  cmp    -0x8(%rsp),%rdx
  jne    L13
  mov    (%rsp),%r15
  addl   $0x1,0x8(%rsp)
  add    %r15,-0x78(%rsp)
  mov    0x8(%rsp),%eax
  add    %r15,-0x10(%rsp)
  add    %r15,%r9
  add    %r15,%r8
  add    %r15,%rdi
  add    %r15,-0x18(%rsp)
  add    %r15,%rsi
  add    %r15,%rcx
  add    %r15,-0x20(%rsp)
  add    %r15,-0x28(%rsp)
  add    %r15,-0x30(%rsp)
  add    %r15,-0x38(%rsp)
  add    %r15,-0x40(%rsp)
  add    %r15,-0x48(%rsp)
  add    %r15,-0x50(%rsp)
  add    %r15,-0x58(%rsp)
  add    %r15,-0x60(%rsp)
  add    %r15,-0x68(%rsp)
  add    %r15,-0x70(%rsp)
  cmp    %eax,0xc(%rsp)
  jne    L35
  addl   $0x1,0x18(%rsp)
  mov    0x100(%rsp),%esi
  mov    0x18(%rsp),%eax
  add    %esi,0x1c(%rsp)
  cmp    %eax,0xf0(%rsp)
  jne    L42
L34:
  add    $0xb8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void rmatmult_3_at(double *dbl, int imin, int imax, int jmin, int jmax, int kmin, int kmax, int jp, int kp, double *dbc, double *dbr, double *dcl, double *dcc, double *dcr, double *dfl, double *dfc, double *dfr, double *cbl, double *cbc, double *cbr, double *ccl, double *ccc, double *ccr, double *cfl, double *cfc, double *cfr, double *ubl, double *ubc, double *ubr, double *ucl, double *ucc, double *ucr, double *ufl, double *ufc, double *ufr, double *x, double *b) {
  int i, ii, jj, kk;
  double *xdbl = x - kp - jp - 1;
  double *xdbc = x - kp - jp;
  double *xdbr = x - kp - jp + 1;
  double *xdcl = x - kp - 1;
  double *xdcc = x - kp;
  double *xdcr = x - kp + 1;
  double *xdfl = x - kp + jp - 1;
  double *xdfc = x - kp + jp;
  double *xdfr = x - kp + jp + 1;
  double *xcbl = x - jp - 1;
  double *xcbc = x - jp;
  double *xcbr = x - jp + 1;
  double *xccl = x - 1;
  double *xccc = x;
  double *xccr = x + 1;
  double *xcfl = x + jp - 1;
  double *xcfc = x + jp;
  double *xcfr = x + jp + 1;
  double *xubl = x + kp - jp - 1;
  double *xubc = x + kp - jp;
  double *xubr = x + kp - jp + 1;
  double *xucl = x + kp - 1;
  double *xucc = x + kp;
  double *xucr = x + kp + 1;
  double *xufl = x + kp + jp - 1;
  double *xufc = x + kp + jp;
  double *xufr = x + kp + jp + 1;
  for (kk = 2; kk < kmax; kk++) {
    for (jj = 2; jj < jmax; jj++) {
      for (ii = 2; ii < imax; ii++) {
        i = ii + jj * jp + kk * kp;
        b[i] = dbl[i] * xdbl[i] + dbc[i] * xdbc[i] + dbr[i] * xdbr[i] + dcl[i] * xdcl[i] + dcc[i] * xdcc[i] + dcr[i] * xdcr[i] + dfl[i] * xdfl[i] + dfc[i] * xdfc[i] + dfr[i] * xdfr[i] + cbl[i] * xcbl[i] + cbc[i] * xcbc[i] + cbr[i] * xcbr[i] + ccl[i] * xccl[i] + ccc[i] * xccc[i] + ccr[i] * xccr[i] + cfl[i] * xcfl[i] + cfc[i] * xcfc[i] + cfr[i] * xcfr[i] + ubl[i] * xubl[i] + ubc[i] * xubc[i] + ubr[i] * xubr[i] + ucl[i] * xucl[i] + ucc[i] * xucc[i] + ucr[i] * xucr[i] + ufl[i] * xufl[i] + ufc[i] * xufc[i] + ufr[i] * xufr[i];
      }
    }
  }
}
```