fbscreenshot: use mmap

should speed things up a little for the hotkey

Author: cobaltgit

src/common/fb.nim

@@ -44,16 +44,8 @@ proc fbclear*() =
 
   zeroMem(fbMap, FbSize)
 
-proc fbscreenshot*(output: string) =
-  let fbFile = system.open("/dev/fb0", fmRead)
-  defer: fbFile.close()
-
-  var fbData: array[FbSize, uint8]
-  let bytesRead = fbFile.readBuffer(addr fbData[0], fbData.len)
-
-  if bytesRead != fbData.len:
-    raise newException(IOError, "Failed to read complete framebuffer data")
-
+proc fbscreenshot*(fbMap: pointer, output: string) =
+  let fbData = cast[ptr UncheckedArray[uint8]](fbMap)
   var rotatedPixels = newSeqUninit[uint8](FbPixels * 4)
 
   for x in 0..<FbWidth:

src/fbscreenshot.nim

@@ -1,5 +1,5 @@
-import std/[cmdline, strformat]
-from common/fb import fbscreenshot
+import std/[cmdline, posix, strformat]
+from common/fb import fbscreenshot, FbSize
 
 when isMainModule:
   if paramCount() < 1:
@@ -9,8 +9,20 @@ when isMainModule:
   let output = paramStr(1)
 
   try:
-    fbscreenshot(output)
-    echo &"fbscreenshot: Saved screenshot to '{output}'"
+    let fbFd = open("/dev/fb0", O_RDONLY)
+    if fbFd < 0:
+      raise newException(IOError, "failed to open framebuffer")
+
+    let fbMap = mmap(nil, FbSize, PROT_READ, MAP_SHARED, fbFd, 0)
+    if fbMap == MAP_FAILED:
+      raise newException(IOError, "failed to map framebuffer")
+
+    try:
+      fbscreenshot(fbMap, output)
+      echo &"fbscreenshot: Saved screenshot to '{output}'"
+    finally:
+      discard close(fbFd)
+      discard munmap(fbMap, FbSize)
   except Exception as e:
     stderr.writeLine &"fbscreenshot: Failed saving screenshot to '{output}': {e.msg}"
     quit(1)

src/quark_hotkeyd/handlers.nim

@@ -1,24 +1,24 @@
 import std/[os, osproc, posix, sets, strformat, strutils, times]
 import ../common/[fb, led, process, reboot]
 
-proc screenshotHandler*() =
+proc screenshotHandler*(fbMap: pointer) =
   setLedTrigger(LedColour.Green, LedTrigger.On)
   let now = now()
   let filename = &"/mnt/SDCARD/Saves/screenshots/Screenshot_{now.year:04}{ord(now.month):02}{now.monthday:02}_{now.hour:02}{now.minute:02}{now.second:02}.png"
-  
+
   try:
-    fbscreenshot(filename)
+    fbscreenshot(fbMap, filename)
   except:
     discard
-  
+
   setLedTrigger(LedColour.Green, LedTrigger.Off)
 
 proc quicksaveHandler*() =
   discard startProcess("/bin/sh", args = @["/mnt/SDCARD/System/scripts/quicksave.sh"])
 
 proc killHandler*() =
   var cmdPid = -1
-  
+
   for kind, path in walkDir("/proc"):
     if kind == pcDir:
       let name = path.extractFilename()
@@ -37,7 +37,7 @@ proc killHandler*() =
     var tree = initHashSet[int]()
     tree.incl(cmdPid)
     getProcessChildren(cmdPid, tree)
-    
+
     for pid in tree:
       discard kill(Pid(pid), SIGTERM)
 

src/quark_hotkeyd/main.nim

@@ -3,6 +3,8 @@ import std/[posix, times, options, monotimes]
 import ../common/evdev
 import handlers
 
+from ../common/fb import FbSize
+
 const
   InputDev = "/dev/input/event0"
 
@@ -96,27 +98,42 @@ proc shouldFire(self: var HotkeyEvent, chordDown: bool): bool =
       return false
 
 proc main() =
-  let fd = posix.open(InputDev, O_RDONLY or O_NONBLOCK)
-  if fd < 0:
-    stderr.writeLine "Failed to open input device"
+  let fbFd = open("/dev/fb0", O_RDONLY)
+  if fbFd < 0:
+    stderr.writeLine "failed to open framebuffer"
+    quit(1)
+
+  let fbMap = mmap(nil, FbSize, PROT_READ, MAP_SHARED, fbFd, 0)
+  if fbMap == MAP_FAILED:
+    discard close(fbFd)
+    stderr.writeLine "failed to mmap framebuffer"
+    quit(1)
+
+  defer:
+    discard munmap(fbMap, FbSize)
+    discard close(fbFd)
+
+  let evFd = posix.open(InputDev, O_RDONLY or O_NONBLOCK)
+  if evFd < 0:
+    stderr.writeLine "failed to open " & InputDev
     quit(1)
 
-  defer: discard close(fd)
+  defer: discard close(evFd)
 
   var pressedKeys = newKeyBitSet()
 
   var hotkeys = @[
-    newPressHotkey(@[KeyCode.KEY_RIGHTCTRL, KeyCode.KEY_PAGEDOWN], screenshotHandler),
+    newPressHotkey(@[KeyCode.KEY_RIGHTCTRL, KeyCode.KEY_PAGEDOWN], proc() = screenshotHandler(fbMap)),
     newPressHotkey(@[KeyCode.KEY_RIGHTCTRL, KeyCode.KEY_PAGEUP], quicksaveHandler),
     newPressHotkey(@[KeyCode.KEY_ENTER, KeyCode.KEY_PAGEUP], killHandler),
     newHoldHotkey(@[KeyCode.KEY_RIGHTCTRL, KeyCode.KEY_ENTER], initDuration(seconds = 10), rebootHandler),
   ]
 
   while true:
-    if pollReadable(fd, 250):
+    if pollReadable(evFd, 250):
       var event: InputEvent
       while true:
-        let bytesRead = read(fd, addr event, sizeof(InputEvent))
+        let bytesRead = read(evFd, addr event, sizeof(InputEvent))
         if bytesRead != sizeof(InputEvent):
           break