From 504256c2a189676c71717971e3380d052d9240b6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20J=C3=B8rgensen?=
 <michael.finn.jorgensen@gmail.com>
Date: Wed, 28 Oct 2020 08:01:31 +0100
Subject: [PATCH] Add test_isr.c

See Issues #77 and #138.
---
 c/test_programs/test_isr.c     | 48 ++++++++++++++++++++++++++++------
 c/vbcc/machines/qnice/sysdef.h |  1 +
 monitor/sysdef.asm             |  1 +
 3 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/c/test_programs/test_isr.c b/c/test_programs/test_isr.c
index 1e392f47..1c0b3e2b 100644
--- a/c/test_programs/test_isr.c
+++ b/c/test_programs/test_isr.c
@@ -1,26 +1,55 @@
+// This program is a test for writing ISR's in pure C.
+//
+// Compile with the command "qvc test_isr.c"
+//
+// The program runs for a few seconds, and should then print the result
+// count=30000
+// sum=50744
+//
+// While running, the program displays a pattern of alternating lines on the
+// VGA screen. There should be no flickering in this pattern.
+
+
 #include <stdio.h>
 #include <sysdef.h>
+#include "qmon.h"    // Random generator
 
 // convenient mechanism to access QNICE's Memory Mapped IO registers
 #define MMIO( __x ) *((unsigned int volatile *) __x )
 
-static unsigned int counter;
+unsigned int count = 0;
+unsigned int sum = 0;
 
-static __interrupt __norbank void isr(void)
+static __interrupt void isr(void)
 {
-   counter++;
-}
+   // Do some calculations that use the EAE.
+   sum += qmon_rand();
+   count += 1;
+} // isr
 
 int main()
 {
-   // Configure a one-second timer interrupt
+   // Enable timer interrupt @ 10000 Hz
    MMIO(IO_TIMER_0_INT) = (unsigned int) isr;
-   MMIO(IO_TIMER_0_PRE) = 100;
-   MMIO(IO_TIMER_0_CNT) = 1000;
+   MMIO(IO_TIMER_0_PRE) = 10;
+   MMIO(IO_TIMER_0_CNT) = 1;
+
+   // Initialize random number
+   qmon_srand(1);
+
+   // Enable user palette
+   MMIO(VGA_PALETTE_OFFS) = VGA_PALETTE_OFFS_USER;
+   MMIO(VGA_PALETTE_ADDR) = VGA_PALETTE_OFFS_USER+16;
 
    while (1)
    {
-      printf("%u\n", counter);
+      if (count >= 30000)
+         break;
+
+      // Set background colour using the EAE
+      MMIO(IC_CSR) |= IC_BLOCK_INTERRUPTS;
+      MMIO(VGA_PALETTE_DATA) = MMIO(VGA_SCAN_LINE)*65;
+      MMIO(IC_CSR) &= IC_BLOCK_INTERRUPTS_INVERT;
 
       if (MMIO(IO_UART_SRA) & 1)
       {
@@ -38,6 +67,9 @@ int main()
    MMIO(IO_TIMER_0_PRE) = 0;
    MMIO(IO_TIMER_0_CNT) = 0;
 
+   printf("count=%u\n", count);
+   printf("sum=%u\n", sum);
+
    return 0;
 }
 
diff --git a/c/vbcc/machines/qnice/sysdef.h b/c/vbcc/machines/qnice/sysdef.h
index 800d6747..fc0028da 100644
--- a/c/vbcc/machines/qnice/sysdef.h
+++ b/c/vbcc/machines/qnice/sysdef.h
@@ -222,6 +222,7 @@
     //             programming.
 #define IC_ENABLE_INTERRUPTS   	0x0001
 #define IC_BLOCK_INTERRUPTS    	0x0002
+#define IC_BLOCK_INTERRUPTS_INVERT    	0xFFFD
 //
 //---------------------------------------------------------------------------------------
 //  Block FFE8: SYSINFO
diff --git a/monitor/sysdef.asm b/monitor/sysdef.asm
index e71647aa..b709b183 100644
--- a/monitor/sysdef.asm
+++ b/monitor/sysdef.asm
@@ -231,6 +231,7 @@ IC$CSR              .EQU 0xFF50 ; Global Interrupt Enable
     ;             programming.
 IC$ENABLE_INTERRUPTS    .EQU 0x0001
 IC$BLOCK_INTERRUPTS     .EQU 0x0002
+IC$BLOCK_INTERRUPTS_INVERT     .EQU 0xFFFD
 ;
 ;---------------------------------------------------------------------------------------
 ;  Block FFE8: SYSINFO