# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1509747906 -3600
# Node ID 9b3b13a6273395d9ae106267febd44eed67f813c
# Parent  eebebd2d4062cb848097085423179e805946ff37
Removed redundant operations such as loads whose values are already loaded.
The line channel also does not need disabling and enabling when updating the
source address.

diff -r eebebd2d4062 -r 9b3b13a62733 vga.S
--- a/vga.S	Fri Nov 03 01:20:19 2017 +0100
+++ b/vga.S	Fri Nov 03 23:25:06 2017 +0100
@@ -720,7 +720,6 @@
 
 	/* Clear the timer interrupt condition. */
 
-	li $v1, (1 << 9)	/* IFS0<9> = T2IF = 0 */
 	sw $v1, CLR($v0)
 
 	/*
@@ -759,7 +758,6 @@
 
 	/* Clear the DMA interrupt condition. */
 
-	li $v1, (1 << 28)	/* IFS1<28> = DMA0IF = 0 */
 	sw $v1, CLR($v0)
 
 	/* Test the block transfer completion interrupt flag. */
@@ -772,7 +770,6 @@
 
 	/* Clear the block transfer completion interrupt flag. */
 
-	li $v1, (1 << 3)	/* CHBCIF = 0 */
 	sw $v1, CLR($v0)
 
 	/*
@@ -918,12 +915,6 @@
 
 	la $s1, vfp_active
 
-	/* Clear the timer interrupt condition. */
-
-	la $v0, IFS0
-	li $v1, (1 << 9)	/* IFS0<9> = T2IF = 0 */
-	sw $v1, CLR($v0)
-
 	/* Re-enable the timer interrupt after the visible period. */
 
 	la $v0, IEC0
@@ -983,22 +974,11 @@
 
 _visible_dma_update:
 
-	/* Disable line channel. */
-
-	la $v0, DCH0CON
-	li $v1, 0b10000000
-	sw $v1, CLR($v0)
-
 	/* Update the source address. */
 
 	la $v0, DCH0SSA
 	sw $s2, 0($v0)
 
-	/* Enable line channel. */
-
-	la $v0, DCH0CON
-	sw $v1, SET($v0)
-
 _visible_update_ret:
 	j irq_exit
 	nop