From ac7cd4d356d6fd2e13ab06b32ece86eb5f629bc4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20J=C3=B8rgensen?=
 <michael.finn.jorgensen@gmail.com>
Date: Thu, 29 Oct 2020 11:41:28 +0100
Subject: [PATCH] Add math interrupt test program

---
 c/test_programs/test_math_isr.c | 139 ++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 c/test_programs/test_math_isr.c

diff --git a/c/test_programs/test_math_isr.c b/c/test_programs/test_math_isr.c
new file mode 100644
index 00000000..13c272c2
--- /dev/null
+++ b/c/test_programs/test_math_isr.c
@@ -0,0 +1,139 @@
+// This is a test program to verify that math operations are interrupt safe.
+//
+// The program runs for approximately 10 seconds and can be interrupted by
+// pressing any key.
+//
+// The expected output (when running on the hardware) is:
+//   Finished!
+//   cycles       = 7665 (ca.)
+//   loop_count   = 712451 (ca.)
+//   isr_count    = 500000
+//   error_count1 = 0
+//   error_count2 = 0
+//   isr_results  = 68041169, 135708334, 203148773, 269872203, 336269884, 404026614, 470963936,
+//
+// The idea in the program is to generate random numbers (which use the EAE) in the ISR,
+// and to sum the results of these together, so the calculation can be verified.
+// In the main loop various math operations are performed in such a way so that the
+// results can be verified.
+
+#include <stdio.h>
+#include <qmon.h>
+
+// convenient mechanism to access QNICE's Memory Mapped IO registers
+#define MMIO( __x ) *((unsigned int volatile *) __x )
+
+volatile unsigned long isr_sum = 0;
+volatile unsigned long isr_count = 0;
+
+#define NUM_RESULTS 7
+volatile unsigned long isr_results[NUM_RESULTS];
+volatile unsigned int  isr_enabled = 0;
+
+static __interrupt void isr(void)
+{
+   if (isr_enabled)
+   {
+      isr_count += 1;
+
+      // Do some calculations that use the EAE.
+      isr_sum += qmon_rand();
+
+      if ((isr_count & 0xFFF) == 0xFFF)
+      {
+         int index = isr_count >> 12;
+         if (index < NUM_RESULTS)
+         {
+            isr_results[index] = isr_sum;
+         }
+      }
+   }
+} // isr
+
+int main()
+{
+   // Enable timer interrupt @ 50000 Hz
+   MMIO(IO_TIMER_0_INT) = (unsigned int) isr;
+   MMIO(IO_TIMER_0_PRE) = 1;
+   MMIO(IO_TIMER_0_CNT) = 1;
+
+   // Initialize random number
+   qmon_srand(1);
+
+   unsigned long loop_count = 0;
+
+   unsigned int cycles = MMIO(IO_CYC_MID);
+
+   isr_enabled = 1;
+
+   unsigned int error_count1 = 0;
+   unsigned int error_count2 = 0;
+
+   while (isr_count < 500000)
+   {
+      ++loop_count;
+
+      // Generate two different numbers
+      unsigned int o11 = loop_count + 1;
+      unsigned int o21 = loop_count + 2;
+
+      // Calculate the product using two different methods
+      unsigned long r1 = qmon_mulu(o11, o21);
+      unsigned long e1 = ((unsigned long) o11) * ((unsigned long) o21); // Calls ___mulint32
+
+      // Compare the result
+      if (r1 != e1)
+      {
+         ++error_count1;
+      }
+
+      unsigned int o12 = loop_count & 0xFF;
+      unsigned int o22 = (loop_count+1) & 0xFF;
+
+      if (o22)
+      {
+         unsigned int r2 = (o12*o22) / o22;  // Two inline assembly operations using EAE
+         unsigned int e2 = o12;
+
+         if (r2 != e2)
+         {
+            ++error_count2;
+         }
+      }
+
+      if (MMIO(IO_UART_SRA) & 1)
+      {
+         unsigned int tmp = MMIO(IO_UART_RHRA);
+         break;
+      }
+      if (MMIO(IO_KBD_STATE) & KBD_NEW_ANY)
+      {
+         unsigned int tmp = MMIO(IO_KBD_DATA);
+         break;
+      }
+   }
+
+   isr_enabled = 0;
+
+   cycles = MMIO(IO_CYC_MID) - cycles;
+
+   printf("Finished!\n");
+   printf("cycles       = %u\n", cycles);
+   printf("loop_count   = %lu\n",loop_count);
+   printf("isr_count    = %lu\n",isr_count);
+   printf("error_count1 = %u\n", error_count1);
+   printf("error_count2 = %u\n", error_count2);
+   printf("isr_results  = ");
+   for (int i=0; i<NUM_RESULTS; ++i)
+   {
+      printf("%lu, ", isr_results[i]);
+   }
+   printf("\n");
+
+   // Disable timer interrupt
+   MMIO(IO_TIMER_0_PRE) = 0;
+   MMIO(IO_TIMER_0_CNT) = 0;
+
+   return 0;
+}
+