Re: [Qemu-devel] [PATCH v4 01/30] vmstate: reduce code duplication

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Michael S. Tsirkin (mst@redhat.com) wrote:
> move size offset and number of elements math out
> to functions, to reduce code duplication.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  vmstate.c | 97 ++++++++++++++++++++++++++++++++++-----------------------------
>  1 file changed, 52 insertions(+), 45 deletions(-)
> 
> diff --git a/vmstate.c b/vmstate.c
> index b689f2f..dc99e1a 100644
> --- a/vmstate.c
> +++ b/vmstate.c
> @@ -10,6 +10,50 @@ static void vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
>  static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
>                                     void *opaque);
>  
> +static int vmstate_n_elems(void *opaque, VMStateField *field)
> +{
> +    int n_elems = 1;
> +
> +    if (field->flags & VMS_ARRAY) {
> +        n_elems = field->num;
> +    } else if (field->flags & VMS_VARRAY_INT32) {
> +        n_elems = *(int32_t *)(opaque+field->num_offset);
> +    } else if (field->flags & VMS_VARRAY_UINT32) {
> +        n_elems = *(uint32_t *)(opaque+field->num_offset);
> +    } else if (field->flags & VMS_VARRAY_UINT16) {
> +        n_elems = *(uint16_t *)(opaque+field->num_offset);
> +    } else if (field->flags & VMS_VARRAY_UINT8) {
> +        n_elems = *(uint8_t *)(opaque+field->num_offset);
> +    }
> +
> +    return n_elems;
> +}
> +
> +static int vmstate_size(void *opaque, VMStateField *field)
> +{
> +    int size = field->size;
> +
> +    if (field->flags & VMS_VBUFFER) {
> +        size = *(int32_t *)(opaque+field->size_offset);
> +        if (field->flags & VMS_MULTIPLY) {
> +            size *= field->size;
> +        }
> +    }
> +
> +    return size;
> +}
> +
> +static void *vmstate_base_addr(void *opaque, VMStateField *field)
> +{
> +    void *base_addr = opaque + field->offset;
> +
> +    if (field->flags & VMS_POINTER) {
> +        base_addr = *(void **)base_addr + field->start;
> +    }
> +
> +    return base_addr;
> +}
> +
>  int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>                         void *opaque, int version_id)
>  {
> @@ -36,30 +80,10 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>               field->field_exists(opaque, version_id)) ||
>              (!field->field_exists &&
>               field->version_id <= version_id)) {
> -            void *base_addr = opaque + field->offset;
> -            int i, n_elems = 1;
> -            int size = field->size;
> -
> -            if (field->flags & VMS_VBUFFER) {
> -                size = *(int32_t *)(opaque+field->size_offset);
> -                if (field->flags & VMS_MULTIPLY) {
> -                    size *= field->size;
> -                }
> -            }
> -            if (field->flags & VMS_ARRAY) {
> -                n_elems = field->num;
> -            } else if (field->flags & VMS_VARRAY_INT32) {
> -                n_elems = *(int32_t *)(opaque+field->num_offset);
> -            } else if (field->flags & VMS_VARRAY_UINT32) {
> -                n_elems = *(uint32_t *)(opaque+field->num_offset);
> -            } else if (field->flags & VMS_VARRAY_UINT16) {
> -                n_elems = *(uint16_t *)(opaque+field->num_offset);
> -            } else if (field->flags & VMS_VARRAY_UINT8) {
> -                n_elems = *(uint8_t *)(opaque+field->num_offset);
> -            }
> -            if (field->flags & VMS_POINTER) {
> -                base_addr = *(void **)base_addr + field->start;
> -            }
> +            void *base_addr = vmstate_base_addr(opaque, field);
> +            int i, n_elems = vmstate_n_elems(opaque, field);
> +            int size = vmstate_size(opaque, field);
> +
>              for (i = 0; i < n_elems; i++) {
>                  void *addr = base_addr + size * i;
>  
> @@ -102,27 +126,10 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
>      while (field->name) {
>          if (!field->field_exists ||
>              field->field_exists(opaque, vmsd->version_id)) {
> -            void *base_addr = opaque + field->offset;
> -            int i, n_elems = 1;
> -            int size = field->size;
> -
> -            if (field->flags & VMS_VBUFFER) {
> -                size = *(int32_t *)(opaque+field->size_offset);
> -                if (field->flags & VMS_MULTIPLY) {
> -                    size *= field->size;
> -                }
> -            }
> -            if (field->flags & VMS_ARRAY) {
> -                n_elems = field->num;
> -            } else if (field->flags & VMS_VARRAY_INT32) {
> -                n_elems = *(int32_t *)(opaque+field->num_offset);
> -            } else if (field->flags & VMS_VARRAY_UINT32) {
> -                n_elems = *(uint32_t *)(opaque+field->num_offset);
> -            } else if (field->flags & VMS_VARRAY_UINT16) {
> -                n_elems = *(uint16_t *)(opaque+field->num_offset);
> -            } else if (field->flags & VMS_VARRAY_UINT8) {
> -                n_elems = *(uint8_t *)(opaque+field->num_offset);
> -            }
> +            void *base_addr = vmstate_base_addr(opaque, field);
> +            int i, n_elems = vmstate_n_elems(opaque, field);
> +            int size = vmstate_size(opaque, field);
> +
>              if (field->flags & VMS_POINTER) {
>                  base_addr = *(void **)base_addr + field->start;
>              }

Hmm, shouldn't those last 3 lines be deleted as well - the logic is
now in vmstate_base_addr?


Dave

> -- 
> MST
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK