From bc58f2b8dc5f65482e490ea832b6f715918b586d Mon Sep 17 00:00:00 2001
From: wheremyfoodat <gponiris2004@gmail.com>
Date: Mon, 29 Aug 2022 04:16:43 +0300
Subject: [PATCH] Document lines with overlapping vertices

---
 docs/cpuspecifications.md         | 6 +++---
 docs/graphicsprocessingunitgpu.md | 3 ++-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/docs/cpuspecifications.md b/docs/cpuspecifications.md
index c7da31a..48b62b0 100644
--- a/docs/cpuspecifications.md
+++ b/docs/cpuspecifications.md
@@ -351,12 +351,12 @@ Note that the instruction following the branch will always be executed.<br/>
   bgez   rs,dest     if rs>=0  then pc=$+4+(-8000h..+7FFFh)*4
   bgtz   rs,dest     if rs>0   then pc=$+4+(-8000h..+7FFFh)*4
   blez   rs,dest     if rs<=0  then pc=$+4+(-8000h..+7FFFh)*4
-  bltzal rs,dest     ra=$+8; if rs<0   then pc=$+4+(..)*4
-  bgezal rs,dest     ra=$+8; if rs>=0  then pc=$+4+(..)*4
+  bltzal rs,dest     if rs<0   then pc=$+4+(..)*4; ra=$+8; 
+  bgezal rs,dest     if rs>=0  then pc=$+4+(..)*4; ra=$+8;
 ```
 
 jr/jalr can be used to jump to an unaligned address, in which case an address error (AdEL) exception will be raised on the next instruction fetch.<br/>
-Additionally, bltzal/bgezal will always place the return address in $ra, whether or not the branch is taken<br/>
+Additionally, bltzal/bgezal will always place the return address in $ra, whether or not the branch is taken. Additionally, if `rs` is $ra, then the value used for the comparison is $ra's value before linking.<br/>
 
 #### JALR cautions
 Caution: The JALR source code syntax varies (IDT79R3041 specs say "jalr rs,rd",
diff --git a/docs/graphicsprocessingunitgpu.md b/docs/graphicsprocessingunitgpu.md
index de913f5..88d6c56 100644
--- a/docs/graphicsprocessingunitgpu.md
+++ b/docs/graphicsprocessingunitgpu.md
@@ -231,8 +231,9 @@ Vertex     YYYYXXXX    - required, two signed 16 bits values
 When polyline mode is active, at least two vertices must be sent to the GPU.
 The vertex list is terminated by the bits 12-15 and 28-31 equaling `0x5`, or
 `(word & 0xF000F000) == 0x50005000`. The terminator value occurs on the first
-word of the vertex (i.e. the color word if it's a gouraud shaded).
+word of the vertex (i.e. the color word if it's a gouraud shaded).<br/>
 
+If the 2 vertices in a line overlap, then the GPU will draw a 1x1 rectangle in the location of the 2 vertices using the colour of the first vertex.
 
 #### Note
 Lines are displayed up to \<including\> their lower-right coordinates (ie.