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

```asm
<effective_transpose>:
  endbr64
  push   %r15
  mov    %edx,%r10d
  push   %r14
  push   %r13
  lea    -0xf(%rdx),%r13d
  push   %r12
  mov    %rsi,%r12
  push   %rbp
  push   %rbx
  mov    %rdi,-0x18(%rsp)
  test   %r13d,%r13d
  jle    L62
  mov    %edx,%eax
  mov    %rdi,-0x28(%rsp)
  movslq %edx,%rsi
  xor    %r14d,%r14d
  movq   $0x0,-0x20(%rsp)
  shl    $0x4,%eax
  shl    $0x2,%rsi
  cltq
  mov    %rax,-0x10(%rsp)
  shl    $0x2,%rax
  mov    %rax,-0x30(%rsp)
  lea    0x40(%r12),%rax
  mov    %rax,-0x8(%rsp)
L74:
  mov    -0x20(%rsp),%rbx
  mov    -0x8(%rsp),%rax
  mov    %r14d,%r15d
  xor    %r11d,%r11d
  lea    0x10(%r14),%r9d
  lea    (%rax,%rbx,4),%rbp
  mov    -0x28(%rsp),%rbx
L65:
  mov    %rbp,%rcx
  mov    %rbx,%r8
  mov    %r15d,%edi
  nopl   0x0(%rax,%rax,1)
L91:
  mov    %edi,-0x38(%rsp)
  lea    -0x40(%rcx),%rax
  mov    %r8,%rdx
  nopl   0x0(%rax,%rax,1)
L25:
  mov    (%rax),%edi
  add    $0x4,%rax
  mov    %edi,(%rdx)
  add    %rsi,%rdx
  cmp    %rcx,%rax
  jne    L25
  mov    -0x38(%rsp),%edi
  add    $0x4,%r8
  lea    (%rax,%rsi,1),%rcx
  add    $0x1,%edi
  cmp    %r9d,%edi
  jne    L91
  add    $0x10,%r11
  add    -0x30(%rsp),%rbx
  add    $0x40,%rbp
  cmp    %r11d,%r13d
  jg     L65
  add    $0x10,%r14
  mov    -0x10(%rsp),%rbx
  addq   $0x40,-0x28(%rsp)
  add    %rbx,-0x20(%rsp)
  cmp    %r14d,%r13d
  jg     L74
  lea    -0x10(%r10),%eax
  and    $0xfffffff0,%eax
  lea    0x10(%rax),%r8d
  cmp    %r8d,%r10d
  jle    L5
L84:
  mov    -0x18(%rsp),%rbx
  movslq %r8d,%rax
  mov    %r8d,%r14d
  movslq %r10d,%rsi
  imul   %r10d,%r14d
  lea    0x0(,%rsi,4),%rdi
  mov    %r8d,%ebp
  lea    (%rbx,%rax,4),%r13
  mov    %r10d,%ebx
  lea    0x40(%r12),%r15
  shl    $0x4,%ebx
  movslq %ebx,%rbx
  shl    $0x2,%rbx
L113:
  test   %r8d,%r8d
  je     L71
  movslq %r14d,%rax
  mov    %r13,%r11
  xor    %r9d,%r9d
  lea    (%r15,%rax,4),%rcx
L83:
  mov    %rsi,-0x38(%rsp)
  lea    -0x40(%rcx),%rax
  mov    %r11,%rdx
L58:
  mov    (%rax),%esi
  add    $0x4,%rax
  mov    %esi,(%rdx)
  add    %rdi,%rdx
  cmp    %rax,%rcx
  jne    L58
  add    $0x10,%r9d
  mov    -0x38(%rsp),%rsi
  add    %rbx,%r11
  add    $0x40,%rcx
  cmp    %r8d,%r9d
  jl     L83
L71:
  add    $0x1,%ebp
  add    %r10d,%r14d
  add    $0x4,%r13
  cmp    %ebp,%r10d
  jne    L113
L52:
  mov    %r8d,%eax
  mov    -0x18(%rsp),%rbx
  lea    -0x1(%r10),%ecx
  movslq %r8d,%rbp
  imul   %r10d,%eax
  sub    %r8d,%ecx
  shl    $0x2,%rsi
  xor    %r11d,%r11d
  xor    %r9d,%r9d
  add    %rbp,%rcx
  lea    0x4(%r12),%r13
  cltq
  lea    (%rbx,%rax,4),%rbx
L110:
  cmp    %r8d,%r10d
  jle    L109
  movslq %r11d,%rdx
  lea    0x0(%rbp,%rdx,1),%rax
  add    %rcx,%rdx
  lea    0x0(%r13,%rdx,4),%r14
  lea    (%r12,%rax,4),%rax
  mov    %rbx,%rdx
L18:
  mov    (%rax),%edi
  add    $0x4,%rax
  mov    %edi,(%rdx)
  add    %rsi,%rdx
  cmp    %rax,%r14
  jne    L18
L109:
  add    $0x1,%r9d
  add    $0x4,%rbx
  add    %r10d,%r11d
  cmp    %r9d,%r10d
  jg     L110
L67:
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L62:
  xor    %r8d,%r8d
  cmp    %r8d,%r10d
  jg     L84
L5:
  test   %r10d,%r10d
  jle    L67
  movslq %r10d,%rsi
  jmp    L52
```

assistant: ```c
void effective_transpose(int *dst, int *src, int N) {
  int i, j, a, b;
  for (i = 0; i <= N - 16; i += 16)
    for (j = 0; j <= N - 16; j += 16)
      for (a = i; a < i + 16; a++)
        for (b = j; b < j + 16; b++)
          dst[b * N + a] = src[a * N + b];
  int offset = i;
  for (i = offset; i <= N - 1; i++)
    for (j = 0; j < offset; j += 16)
      for (b = j; b < j + 16; b++)
        dst[b * N + i] = src[i * N + b];
  for (i = 0; i <= N - 1; i++)
    for (j = offset; j <= N - 1; j++)
      dst[j * N + i] = src[i * N + j];
}
```