Intel Surface Layout (ISL)

The Intel Surface Layout library (ISL) is a subproject in Mesa for doing surface layout calculations for Intel graphics drivers. It was originally written by Chad Versace and is now maintained by Jason Ekstrand and Nanley Chery.

The core representation of a surface in ISL is isl_surf.

struct isl_surf

Public Members

enum isl_surf_dim dim

Dimensionality of the surface

enum isl_dim_layout dim_layout

Spatial layout of the surface in memory

This is dependent on isl_surf::dim and hardware generation.

enum isl_msaa_layout msaa_layout

Spatial layout of the samples if isl_surf::samples > 1

enum isl_tiling tiling

Memory tiling used by the surface

enum isl_format format

Base image format of the surface

This need not be the same as the format specified in isl_view::format when a surface state is constructed. It must, however, have the same number of bits per pixel or else memory calculations will go wrong.

struct isl_extent3d image_alignment_el

Alignment of the upper-left sample of each subimage, in units of surface elements.

struct isl_extent4d logical_level0_px

Logical extent of the surface’s base level, in units of pixels. This is identical to the extent defined in isl_surf_init_info.

struct isl_extent4d phys_level0_sa

Physical extent of the surface’s base level, in units of physical surface samples.

Consider isl_dim_layout as an operator that transforms a logical surface layout to a physical surface layout. Then

logical_layout := (isl_surf::dim, isl_surf::logical_level0_px) isl_surf::phys_level0_sa := isl_surf::dim_layout * logical_layout

uint32_t levels

Number of miplevels in the surface

uint32_t samples

Number of samples in the surface


samples >= 1

uint64_t size_B

Total size of the surface, in bytes.

uint32_t alignment_B

Required alignment for the surface’s base address.

uint32_t row_pitch_B

The interpretation of this field depends on the value of isl_tile_info::physical_extent_B. In particular, the width of the surface in tiles is row_pitch_B / isl_tile_info::physical_extent_B.width and the distance in bytes between vertically adjacent tiles in the image is given by row_pitch_B * isl_tile_info::physical_extent_B.height.

For linear images where isl_tile_info::physical_extent_B.height == 1, this cleanly reduces to being the distance, in bytes, between vertically adjacent surface elements.



uint32_t array_pitch_el_rows

Pitch between physical array slices, in rows of surface elements.

isl_surf_usage_flags_t usage

Copy of isl_surf_init_info::usage.