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

```asm
<fwd>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    0x48(%rsp),%r15d
  mov    %rdi,-0x20(%rsp)
  mov    %rsi,-0x18(%rsp)
  mov    %rdx,-0x10(%rsp)
  mov    %r8d,-0x28(%rsp)
  mov    %r9d,-0x24(%rsp)
  test   %r9d,%r9d
  jle    L55
  mov    0x38(%rsp),%eax
  mov    0x38(%rsp),%ebx
  mov    %rcx,%r10
  movl   $0x0,-0x38(%rsp)
  mov    0x38(%rsp),%r9d
  movslq 0x38(%rsp),%r11
  imul   %r15d,%eax
  neg    %r9d
  shl    $0x2,%r11
  movslq %r9d,%r9
  mov    %eax,-0x34(%rsp)
  lea    0x1(%r15),%eax
  shl    $0x2,%r9
  imul   0x38(%rsp),%eax
  mov    %eax,-0x30(%rsp)
  lea    -0x1(%r15),%eax
  imul   %eax,%ebx
  mov    %ebx,-0x2c(%rsp)
  movslq %r15d,%rbx
  mov    %rbx,-0x8(%rsp)
  movslq %r8d,%rbx
  lea    0x2(%rax),%r8
  mov    %rbx,-0x40(%rsp)
  nopl   0x0(%rax)
L49:
  mov    -0x28(%rsp),%eax
  test   %eax,%eax
  jle    L0
  movslq -0x34(%rsp),%rax
  mov    -0x8(%rsp),%rbx
  movslq -0x30(%rsp),%r14
  movslq -0x2c(%rsp),%r13
  lea    (%rbx,%rax,1),%r12
  mov    -0x18(%rsp),%rbx
  shl    $0x2,%r12
  sub    %rax,%r14
  sub    %rax,%r13
  lea    (%rbx,%r12,1),%rdi
  mov    -0x20(%rsp),%rbx
  shl    $0x2,%r14
  shl    $0x2,%r13
  lea    (%rbx,%r12,1),%rbp
  add    -0x10(%rsp),%r12
  xor    %ebx,%ebx
  nopw   0x0(%rax,%rax,1)
L15:
  movss  (%rdi),%xmm1
  movaps %xmm1,%xmm2
  addss  %xmm1,%xmm2
  mulss  (%r10),%xmm1
  subss  0x0(%rbp,%rbx,4),%xmm2
  test   %r15d,%r15d
  jle    L19
  lea    (%r14,%rdi,1),%rsi
  lea    (%rdi,%r13,1),%rcx
  mov    %rdi,%rdx
  mov    $0x1,%eax
  nopl   0x0(%rax,%rax,1)
L21:
  movss  (%rsi),%xmm0
  addss  (%rcx),%xmm0
  add    %r11,%rsi
  add    %r9,%rcx
  addss  (%rdi,%rax,4),%xmm0
  addss  -0x4(%rdx),%xmm0
  sub    $0x4,%rdx
  mulss  (%r10,%rax,4),%xmm0
  add    $0x1,%rax
  addss  %xmm0,%xmm1
  cmp    %r8,%rax
  jne    L21
L19:
  mulss  (%r12,%rbx,4),%xmm1
  add    $0x4,%rdi
  addss  %xmm2,%xmm1
  movss  %xmm1,0x0(%rbp,%rbx,4)
  add    $0x1,%rbx
  cmp    %rbx,-0x40(%rsp)
  jne    L15
L0:
  mov    0x38(%rsp),%edi
  addl   $0x1,-0x38(%rsp)
  add    %edi,-0x34(%rsp)
  mov    -0x38(%rsp),%eax
  add    %edi,-0x30(%rsp)
  add    %edi,-0x2c(%rsp)
  cmp    %eax,-0x24(%rsp)
  jne    L49
L55:
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void fwd(float *next, float *curr, float *vsq, float *c_coeff, int nx, int ny, int dimx, int dimy, int radius) {
#pragma acc parallel present(next [0:dimx * dimy], curr [0:dimx * dimy], vsq [0:dimx * dimy], c_coeff [0:NUM_COEFF])
#pragma acc loop collapse(2) gang worker vector
  for (int y = 0; y < ny; y++) {
    for (int x = 0; x < nx; x++) {
      int this_offset = (((radius) + (y)) * (dimx) + ((radius) + (x)));
      float temp = 2.0f * curr[this_offset] - next[this_offset];
      float div = c_coeff[0] * curr[this_offset];
#pragma acc loop seq
      for (int d = 1; d <= radius; d++) {
        int y_pos_offset = (((radius) + (y + d)) * (dimx) + ((radius) + (x)));
        int y_neg_offset = (((radius) + (y - d)) * (dimx) + ((radius) + (x)));
        int x_pos_offset = (((radius) + (y)) * (dimx) + ((radius) + (x + d)));
        int x_neg_offset = (((radius) + (y)) * (dimx) + ((radius) + (x - d)));
        div += c_coeff[d] * (curr[y_pos_offset] + curr[y_neg_offset] + curr[x_pos_offset] + curr[x_neg_offset]);
      }
      next[this_offset] = temp + div * vsq[this_offset];
    }
  }
}
```