From c2f6311367327ebc0b5bdfe372ece1f263a9fc2f Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Sat, 8 Jun 2024 00:03:02 +0200
Subject: [PATCH] todo

---
 compiler/res/prog8lib/cx16/verafx.p8 |  4 +++-
 docs/source/libraries.rst            |  9 ++++++++-
 docs/source/todo.rst                 | 21 ++++++++++++++++++++-
 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/compiler/res/prog8lib/cx16/verafx.p8 b/compiler/res/prog8lib/cx16/verafx.p8
index 2e3d2a618..47636a6b5 100644
--- a/compiler/res/prog8lib/cx16/verafx.p8
+++ b/compiler/res/prog8lib/cx16/verafx.p8
@@ -1,6 +1,6 @@
 ; Somewhat experimental Vera FX support.
 ; Docs:
-; https://github.com/X16Community/x16-docs/blob/101759f3bfa5e6cce4e8c5a0b67cb0f2f1c6341e/X16%20Reference%20-%2010%20-%20VERA%20FX%20Reference.md
+; https://github.com/X16Community/x16-docs/blob/fb63156cca2d6de98be0577aacbe4ddef458f896/X16%20Reference%20-%2010%20-%20VERA%20FX%20Reference.md
 ; https://docs.google.com/document/d/1q34uWOiM3Be2pnaHRVgSdHySI-qsiQWPTo_gfE54PTg
 
 verafx {
@@ -166,6 +166,8 @@ verafx {
     }
 
     sub transparency(bool enable) {
+        ; Set transparent write mode for VeraFX cached writes and also for normal writes to DATA0/DATA.
+        ; If enabled, pixels with value 0 do not modify VRAM when written (so they are "transparent")
         cx16.VERA_CTRL = 2<<1       ; dcsel = 2
         if enable
             cx16.VERA_FX_CTRL |= %10000000
diff --git a/docs/source/libraries.rst b/docs/source/libraries.rst
index 6b191fdbe..352c762b9 100644
--- a/docs/source/libraries.rst
+++ b/docs/source/libraries.rst
@@ -228,6 +228,12 @@ and to seek in open files.
 Read the `diskio source code <https://github.com/irmen/prog8/tree/master/compiler/res/prog8lib/cx16/diskio.p8>`_
 to see what's in there. (Note: slight variations for different compiler targets)
 
+.. note::
+    For simplicity sake, this library is designed to work on a *single* open file
+    for reading, and a *single* open file for writing at any time only.
+    If you need to load or save to more than one file at a time, you'll have
+    to write your own I/O routines (or supplement the ones found here)
+
 .. note::
     If you are using the X16 emulator with HostFS, and are experiencing weird behavior with these
     routines, please first try again with an SD-card image instead of HostFs.
@@ -765,7 +771,8 @@ the emulators already support it).
     This routine is about 50% faster as a regular byte-by-byte copy.
 
 ``transparency``
-    Enable or disable transparent writes (color 0 will be transparent if enabled).
+    Set transparent write mode for VeraFX cached writes and also for normal writes to DATA0/DATA.
+    If enabled, pixels with value 0 do not modify VRAM when written (so they are "transparent")
 
 Read the `verafx source code <https://github.com/irmen/prog8/tree/master/compiler/res/prog8lib/cx16/verafx.p8>`_
 to see what's in there.
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index f29e652c5..ba8a9f4bc 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -3,9 +3,28 @@ TODO
 
 https://github.com/irmen/prog8/issues/136 (string.find register order issue)
 
-optimize signed byte/word division by powers of 2, it's now using divmod routine.  (also % ?)
+optimize signed byte/word division by powers of 2 (and shift right?), it's now using divmod routine.  (also % ?)
     see inplacemodificationByteVariableWithLiteralval() and inplacemodificationSomeWordWithLiteralval()
     and for IR: see divideByConst() in IRCodeGen
+    1 shift right of AX signed word:
+                 stx	P8ZP_SCRATCH_B1
+                 cpx	#$80
+                 ror	P8ZP_SCRATCH_B1
+                 ror    a
+                 ldx	P8ZP_SCRATCH_B1
+
+    multi shift right: (amount in $22)
+         sta	$4
+         txa
+         ldx	$22
+         beq    end
+    loop  cmp	#$80
+         ror
+         ror	$4
+         dex
+         bne	loop
+    end:  tax
+         lda	$4
 
 
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