user: Please show me the C implementation that matches the assembly code listed below:

```asm
<spd_set_drb>:
  endbr64
  push   %r15
  lea    D0(%rip),%r15
  push   %r14
  lea    D12(%rip),%r14
  push   %r13
  push   %r12
  push   %rbp
  xor    %ebp,%ebp
  push   %rbx
  mov    $0x50,%ebx
  sub    $0x18,%rsp
L24:
  mov    $0x3,%esi
  mov    %ebx,%edi
  lea    (%rbx,%rbx,1),%r12d
  call   <smbus_read_byte@plt>
  lea    -0x40(%r12),%edx
  mov    %eax,%r13d
  test   %eax,%eax
  jns    L60
L7:
  mov    %edx,0x4(%rsp)
L36:
  mov    %r15,%rdi
  call   <print_debug@plt>
  mov    %ebp,%edi
  call   <print_debug_hex32@plt>
  mov    %r14,%rdi
  call   <print_debug@plt>
  mov    0x4(%rsp),%edx
  mov    %ebp,%ecx
  xor    %esi,%esi
  xor    %edi,%edi
  call   <pcibios_write_config_byte@plt>
L4:
  mov    %r15,%rdi
  add    $0x1,%ebx
  call   <print_debug@plt>
  mov    %ebp,%edi
  call   <print_debug_hex32@plt>
  mov    %r14,%rdi
  call   <print_debug@plt>
  lea    -0x3f(%r12),%edx
  mov    %ebp,%ecx
  xor    %esi,%esi
  xor    %edi,%edi
  call   <pcibios_write_config_byte@plt>
  cmp    $0x54,%ebx
  jne    L24
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax,%rax,1)
L60:
  mov    $0x4,%esi
  mov    %ebx,%edi
  mov    %edx,0xc(%rsp)
  and    $0xf,%r13d
  call   <smbus_read_byte@plt>
  mov    $0x11,%esi
  mov    %ebx,%edi
  mov    %eax,0x8(%rsp)
  call   <smbus_read_byte@plt>
  movslq %eax,%rdi
  call   <log2@plt>
  mov    $0x6,%esi
  mov    %ebx,%edi
  lea    -0x1a(%r13,%rax,1),%ecx
  mov    %ecx,0x4(%rsp)
  call   <smbus_read_byte@plt>
  mov    $0x7,%esi
  mov    %ebx,%edi
  movslq %eax,%r13
  call   <smbus_read_byte@plt>
  movslq %eax,%rdi
  shl    $0x8,%rdi
  or     %r13,%rdi
  call   <log2@plt>
  mov    0x8(%rsp),%r13d
  add    0x4(%rsp),%eax
  mov    %ebx,%edi
  mov    $0x5,%esi
  and    $0xf,%r13d
  add    %eax,%r13d
  call   <smbus_read_byte@plt>
  mov    0xc(%rsp),%edx
  cmp    $0x1,%eax
  jle    L65
  cmp    $0x7,%r13d
  ja     L7
  mov    %r13d,%ecx
  mov    $0x1,%eax
  mov    %r15,%rdi
  mov    %edx,0x4(%rsp)
  shl    %cl,%eax
  add    %eax,%ebp
  mov    %eax,%r13d
  call   <print_debug@plt>
  mov    %ebp,%edi
  call   <print_debug_hex32@plt>
  mov    %r14,%rdi
  call   <print_debug@plt>
  mov    0x4(%rsp),%edx
  mov    %ebp,%ecx
  xor    %esi,%esi
  xor    %edi,%edi
  add    %r13d,%ebp
  call   <pcibios_write_config_byte@plt>
  jmp    L4
  nop
L65:
  cmp    $0x7,%r13d
  ja     L7
  mov    $0x1,%eax
  mov    %r13d,%ecx
  mov    %edx,0x4(%rsp)
  shl    %cl,%eax
  add    %eax,%ebp
  jmp    L36
```

tool_calls: name: unpack_data
arguments: data_tag: D0
type: string
name: unpack_data
arguments: data_tag: D12
type: string

tool: D0: end_of_memory: 

tool: D12: 


assistant: ```c
void spd_set_drb(void) {
  unsigned end_of_memory;
  unsigned char device;
  unsigned char drb_reg;
  end_of_memory = 0;
  device = 0x50;
  while (device <= 0x53) {
    unsigned side1_bits, side2_bits;
    int byte, byte2;
    side1_bits = side2_bits = -1;
    byte = smbus_read_byte(device, 3);
    if (byte >= 0) {
      side1_bits += byte & 0xf;
      byte = smbus_read_byte(device, 4);
      side1_bits += byte & 0xf;
      byte = smbus_read_byte(device, 17);
      side1_bits += log2(byte);
      byte = smbus_read_byte(device, 6);
      byte2 = smbus_read_byte(device, 7);
      side1_bits += log2((((unsigned long)byte2 << 8) | byte));
      side1_bits -= 25;
      byte = smbus_read_byte(device, 5);
      if (byte > 1) {
        side2_bits = side1_bits;
      }
    }
    if (side1_bits < 8) {
      end_of_memory += (1 << side1_bits);
    }
    drb_reg = ((device - 0x50) << 1) + 0x60;
    print_debug("end_of_memory: ");
    print_debug_hex32(end_of_memory);
    print_debug("\n");
    pcibios_write_config_byte(0, ((0x00 << 3) + 0), drb_reg, end_of_memory);
    if (side2_bits < 8) {
      end_of_memory += (1 << side2_bits);
    }
    print_debug("end_of_memory: ");
    print_debug_hex32(end_of_memory);
    print_debug("\n");
    pcibios_write_config_byte(0, ((0x00 << 3) + 0), drb_reg + 1, end_of_memory);
    device += 1;
  }
}
```