Changes: CPU

Revision as of 20:23, 19 December 2018

Pico-8 keeps track of CPU usage using two values: a Lua instruction usage, and a system usage. The function stat(1) return the sum of these values, and stat(2) returns the CPU usage.

Functions with a system cost

Only a handful of functions have a system cost, measured in ticks. There are 4194304 ticks in a second (2^22), so about 69905 ticks in a frame at 60 FPS.

Function	Ticks	Notes
`cls`	`1024`	same cost as `rectfill` of same size
`print`
`spr`
`sspr`
`rect`
`rectfill`	`max(1,flr(n/16))`	`n` is the number of pixels drawn (width × height)
`circ`
`circfill`
`line`	`ceil(n/2)`	`n` is the number of pixels drawn; there is an additional cost of `1` if at least one pixel had to be clipped
`map` / `mapdraw`
`music`	`16`	no cost if no argument
`sfx`	`16`	no cost if no argument
`memcpy`
`memset`
`reload`
`btn`	`4`	no cost if no argument
`btnp`	`4`	no cost if no argument
`rnd`	`4`
`sqrt`	`24`	only `16` if argument is zero
`stat`	`16`

@@ Line 3: / Line 3: @@
 == Functions with a system cost ==
-Only a handful of functions have a system cost:
+Only a handful of functions have a system cost, measured in ticks. There are 4194304 ticks in a second (2^22), so about 69905 ticks in a frame at 60 FPS.
 {|
-| Function || Cost
+| Function || Ticks || Notes
 |-
-| [[cls|<code>cls</code>]] ||
+| [[cls|<code>cls</code>]] || <code>1024</code> || same cost as [[rectfill|<code>rectfill</code>]] of same size
 |-
-| [[print|<code>print</code>]] ||
+| [[print|<code>print</code>]] || ||
 |-
-| [[spr|<code>spr</code>]] ||
+| [[spr|<code>spr</code>]] || ||
 |-
-| [[sspr|<code>sspr</code>]] ||
+| [[sspr|<code>sspr</code>]] || ||
 |-
-| [[rect|<code>rect</code>]] ||
+| [[rect|<code>rect</code>]] || ||
 |-
-| [[rectfill|<code>rectfill</code>]] ||
+| [[rectfill|<code>rectfill</code>]] || <code>max(1,flr(n/16))</code> || <code>n</code> is the number of pixels drawn (width × height)
 |-
-| [[circ|<code>circ</code>]] ||
+| [[circ|<code>circ</code>]] || ||
 |-
-| [[circfill|<code>circfill</code>]] ||
+| [[circfill|<code>circfill</code>]] || ||
 |-
+| [[line|<code>line</code>]] || <code>ceil(n/2)</code> || <code>n</code> is the number of pixels drawn; there is an additional cost of <code>1</code> if at least one pixel had to be clipped
-| [[line|<code>line</code>]] ||
 |-
-| [[map|<code>map</code>]] / [[mapdraw|<code>mapdraw</code>]] ||
+| [[map|<code>map</code>]] / [[mapdraw|<code>mapdraw</code>]] || ||
 |-
-| [[music|<code>music</code>]] ||
+| [[music|<code>music</code>]] || <code>16</code> || no cost if no argument
 |-
-| [[sfx|<code>sfx</code>]] ||
+| [[sfx|<code>sfx</code>]] || <code>16</code> || no cost if no argument
 |-
-| [[memcpy|<code>memcpy</code>]] ||
+| [[memcpy|<code>memcpy</code>]] || ||
 |-
-| [[memset|<code>memset</code>]] ||
+| [[memset|<code>memset</code>]] || ||
 |-
-| [[reload|<code>reload</code>]] ||
+| [[reload|<code>reload</code>]] || ||
 |-
-| [[rnd|<code>rnd</code>]] ||
+| [[btn|<code>btn</code>]] || <code>4</code> || no cost if no argument
 |-
-| [[sqrt|<code>sqrt</code>]] ||
+| [[btnp|<code>btnp</code>]] || <code>4</code> || no cost if no argument
 |-
-| [[btn|<code>btn</code>]] ||
+| [[rnd|<code>rnd</code>]] || <code>4</code> ||
 |-
-| [[btnp|<code>btnp</code>]] ||
+| [[sqrt|<code>sqrt</code>]] || <code>24</code> || only <code>16</code> if argument is zero
 |-
-| [[stat|<code>stat</code>]] ||
+| [[stat|<code>stat</code>]] || <code>16</code> ||
 |}