CPU: Difference between revisions

Revision as of 22:17, 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) returns the total (Lua + system) usage for the current frame, and stat(2) returns the system usage.

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

Function	Ticks	Notes
`cls`	`1024`	same cost as `rectfill` of same size
`print`	`2+n*8`	`n` is the number of characters in the string, even those not rendered spaces, newlines, and double-width glyphs each count as one character
`spr`	n	`n` is the number of pixels drawn, including transparent pixels (width × height of the sprite rectangle) cost is 0 if first argument is outside the [0, 255] range
`sspr`	`n`	`n` is the number of pixels drawn, including transparent pixels (width × height of the destination rectangle)
`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`	`n+1`	`n` is the number of bytes copied
`memset`	`max(1,ceil(n/2))`	`n` is the number of bytes set
`reload`	`max(1,n*8)`	`n` is the number of bytes reloaded
`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 13: / Line 13: @@
 |-
 | [[print|<code>print</code>]] || <code>2+n*8</code>
-||<code>n</code> is the number of characters in the string
+||<code>n</code> is the number of characters in the string, even those not rendered
-spaces and newlines count as one character
+spaces, newlines, and double-width glyphs each count as one character
+|-
+| [[spr|<code>spr</code>]] || n
+||<code>n</code> is the number of pixels drawn, including transparent pixels (width × height of the sprite rectangle)
-double-width glyphs count as one character
+cost is 0 if first argument is outside the [0, 255] range
-offscreen characters count
-|-
-| [[spr|<code>spr</code>]] || ||
 |-
-| [[sspr|<code>sspr</code>]] || ||
+| [[sspr|<code>sspr</code>]] || <code>n</code>
+||<code>n</code> is the number of pixels drawn, including transparent pixels (width × height of the destination rectangle)
 |-
 | [[rect|<code>rect</code>]] || ||