user: What would the C source look like for the assembly code provided here:

```asm
<csr2csc>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %edi,-0x24(%rbp)
  mov    %esi,-0x28(%rbp)
  mov    %edx,-0x2c(%rbp)
  mov    %rcx,-0x38(%rbp)
  mov    %r8,-0x40(%rbp)
  mov    %r9,-0x48(%rbp)
  movl   $0x0,-0x18(%rbp)
  jmp    L19
L94:
  mov    -0x18(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    0x20(%rbp),%rax
  add    %rdx,%rax
  movl   $0x0,(%rax)
  addl   $0x1,-0x18(%rbp)
L19:
  mov    -0x18(%rbp),%eax
  cmp    -0x28(%rbp),%eax
  jle    L94
  movl   $0x0,-0x18(%rbp)
  jmp    L87
L36:
  mov    -0x18(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  cltq
  add    $0x1,%rax
  lea    0x0(,%rax,4),%rdx
  mov    0x20(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  add    $0x1,%edx
  mov    %edx,(%rax)
  addl   $0x1,-0x18(%rbp)
L87:
  mov    -0x18(%rbp),%eax
  cmp    -0x2c(%rbp),%eax
  jl     L36
  movl   $0x0,-0x18(%rbp)
  jmp    L3
L66:
  mov    -0x18(%rbp),%eax
  cltq
  add    $0x1,%rax
  lea    0x0(,%rax,4),%rdx
  mov    0x20(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%ecx
  mov    -0x18(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    0x20(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  mov    -0x18(%rbp),%eax
  cltq
  add    $0x1,%rax
  lea    0x0(,%rax,4),%rsi
  mov    0x20(%rbp),%rax
  add    %rsi,%rax
  add    %ecx,%edx
  mov    %edx,(%rax)
  addl   $0x1,-0x18(%rbp)
L3:
  mov    -0x18(%rbp),%eax
  cmp    -0x28(%rbp),%eax
  jl     L66
  movl   $0x0,-0x18(%rbp)
  mov    -0x48(%rbp),%rax
  mov    %rax,-0x8(%rbp)
  jmp    L80
L20:
  mov    -0x8(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,-0x14(%rbp)
  jmp    L28
L83:
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    %eax,-0x10(%rbp)
  mov    -0x10(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    0x20(%rbp),%rax
  add    %rax,%rdx
  mov    (%rdx),%eax
  lea    0x1(%rax),%ecx
  mov    %ecx,(%rdx)
  mov    %eax,-0xc(%rbp)
  mov    -0xc(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x18(%rbp),%eax
  mov    %eax,(%rdx)
  cmpq   $0x0,-0x38(%rbp)
  je     L25
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x38(%rbp),%rax
  add    %rax,%rdx
  mov    -0xc(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rcx
  mov    0x10(%rbp),%rax
  add    %rcx,%rax
  movsd  (%rdx),%xmm0
  movsd  %xmm0,(%rax)
L25:
  addl   $0x1,-0x14(%rbp)
L28:
  mov    -0x8(%rbp),%rax
  add    $0x4,%rax
  mov    (%rax),%eax
  cmp    %eax,-0x14(%rbp)
  jl     L83
  addl   $0x1,-0x18(%rbp)
  addq   $0x4,-0x8(%rbp)
L80:
  mov    -0x18(%rbp),%eax
  cmp    -0x24(%rbp),%eax
  jl     L20
  mov    -0x28(%rbp),%eax
  mov    %eax,-0x18(%rbp)
  jmp    L8
L79:
  mov    -0x18(%rbp),%eax
  cltq
  shl    $0x2,%rax
  lea    -0x4(%rax),%rdx
  mov    0x20(%rbp),%rax
  add    %rdx,%rax
  mov    -0x18(%rbp),%edx
  movslq %edx,%rdx
  lea    0x0(,%rdx,4),%rcx
  mov    0x20(%rbp),%rdx
  add    %rcx,%rdx
  mov    (%rax),%eax
  mov    %eax,(%rdx)
  subl   $0x1,-0x18(%rbp)
L8:
  cmpl   $0x0,-0x18(%rbp)
  jg     L79
  mov    0x20(%rbp),%rax
  movl   $0x0,(%rax)
  nop
  pop    %rbp
  ret
```

assistant: ```c
void csr2csc(int n, int m, int nz, double *a, int *col_idx, int *row_start, double *csc_a, int *row_idx, int *col_start) {
  int i, j, k, l;
  int *ptr;
  for (i = 0; i <= m; i++)
    col_start[i] = 0;
  for (i = 0; i < nz; i++)
    col_start[col_idx[i] + 1]++;
  for (i = 0; i < m; i++)
    col_start[i + 1] += col_start[i];
  for (i = 0, ptr = row_start; i < n; i++, ptr++)
    for (j = *ptr; j < *(ptr + 1); j++) {
      k = col_idx[j];
      l = col_start[k]++;
      row_idx[l] = i;
      if (a)
        csc_a[l] = a[j];
    }
  for (i = m; i > 0; i--)
    col_start[i] = col_start[i - 1];
  col_start[0] = 0;
}
```