View source for Sprite Attribute Upload

{{Port
|Number=$xx57
|ShortDesc=Uploads sprite positions, visibility and effect flags.
|Readable=No
|Writable=Yes
|Subsystem=Sprites
}}
Uploads attributes of the sprite slot selected by {{PortNo|$303B}}. Attributes are in 4 byte blocks sent in the following order; after sending 4 bytes the address auto-increments to the next sprite. The 4 bytes are as follows:

Byte 1 is the low bits of the X position. Legal X positions are 0-319 if sprites are allowed over the border or 32-287 if not. The MSB is in byte 3.

Byte 2 is the Y position. Legal Y positions are 0-255 if sprites are allowed over the border or 32-223 if not.

Byte 3 is bitmapped:
{|class="wikitable"
! Bit !! Description
|-
| 4-7 || Palette offset, added to each palette index from pattern before drawing
|-
| 3 || Enable X mirror
|-
| 2 || Enable Y mirror
|-
| 1 || Enable rotation
|-
| 0 || MSB of X coordinate
|}

Byte 4 is also bitmapped:
{|class="wikitable"
! Bit !! Description
|-
| 7 || Enable visibility
|-
| 6 || Reserved
|-
| 5-0 || Pattern index ("Name")
|}