added idm-ringbuffer/ringbuffer.c, which contains test code to analyze IDM ringbuffer algorithm

git-svn-id: https://svn.spreadspace.org/mur.sat@519 7de4ea59-55d0-425e-a1af-a3118ea81d4c

1 files changed, 143 insertions, 0 deletions

diff --git a/tools/idm-ringbuffer/ringbuffer.c b/tools/idm-ringbuffer/ringbuffer.c
new file mode 100644
index 0000000..ea912b3
--- /dev/null
+++ b/tools/idm-ringbuffer/ringbuffer.c
@@ -0,0 +1,143 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <termios.h>
+
+#define BUFFER_START 0x2000u
+//#define BUFFER_SIZE 960u
+#define BUFFER_SIZE 10
+#define BUFFER_END (BUFFER_START + BUFFER_SIZE)
+#define RAM_SIZE (BUFFER_END + 1)
+
+#define BOOL int
+#define FALSE 0
+#define TRUE 1
+BOOL overrun = FALSE;
+BOOL overrunForReader = FALSE;
+BOOL underrun = TRUE;
+char picRam[RAM_SIZE] = { 0 };
+char* bufferStart = &(picRam[BUFFER_START]);
+char* bufferEnd = &(picRam[BUFFER_END - 1]);
+char* writePtr = 0;
+char* readPtr = 0;
+BOOL currentByteLoaded = FALSE;
+char spiData = 0;
+
+void debugPrint() {
+  printf("wPtr: %d, rPtr: %d, cbl: %d, ovr: %d, udr: %d\n",
+	 (int) (writePtr - bufferStart),
+	 (int) (readPtr - bufferStart),
+	 (int) currentByteLoaded,
+	 (int) overrun,
+	 (int) underrun);
+  int i;
+  for(i = 0; i < BUFFER_SIZE; ++i) {
+    printf("%02x ", bufferStart[i]);
+  }
+  printf("\n");
+}
+
+int getch(void)
+{
+  int ch;
+  struct termios oldt;
+  struct termios newt;
+  tcgetattr(STDIN_FILENO, &oldt); /*store old settings */
+  newt = oldt; /* copy old settings to new settings */
+  newt.c_lflag &= ~(ICANON | ECHO); /* make one change to old settings in new settings */
+  tcsetattr(STDIN_FILENO, TCSANOW, &newt); /*apply the new settings immediatly */
+  ch = getchar(); /* standard getchar call */
+  tcsetattr(STDIN_FILENO, TCSANOW, &oldt); /*reapply the old settings */
+  return ch; /*return received char */
+}
+
+void incrementWriteIdx() {
+  if (!underrun && (writePtr == readPtr)) {
+    overrun = TRUE;
+    overrunForReader = TRUE;
+  } else {
+    if (!overrun) {
+      writePtr++;
+      writePtr = writePtr > bufferEnd  ? bufferStart : writePtr;
+    }
+    overrun = FALSE;
+    overrunForReader = FALSE;
+    underrun = FALSE;
+  }
+}
+
+void incrementReadIdx() {
+  if (!overrunForReader && (readPtr == writePtr)) {
+    underrun = TRUE;
+  } else {
+    readPtr++;
+    readPtr = readPtr > bufferEnd ? bufferStart : readPtr;
+    underrun = FALSE;
+    overrunForReader = FALSE;
+    // overrun = FALSE;
+  }
+}
+
+void beginRead() {
+  if (!currentByteLoaded) {
+    incrementReadIdx();
+  }
+  if (!underrun) {
+    spiData = *readPtr;
+    printf("SPI out: %02x\n", (int)spiData);
+  }
+  currentByteLoaded = TRUE;
+}
+
+void endRead() {
+  currentByteLoaded = FALSE;
+}
+
+void storeSample() {
+  static char value = 0;
+  value++;
+  incrementWriteIdx();
+  if (!overrun) {
+    *writePtr = value;
+  }
+}
+
+void triggerByteTransferred() {
+  if (spiData == 0) {
+    endRead();
+    beginRead();
+  } else if (spiData == 'r') {
+    beginRead();
+  } else {
+    printf("%s", "I don't like you!");
+  }
+}
+
+int main()
+{
+  writePtr = bufferStart;
+  readPtr = bufferStart;
+
+  char key;
+  for(;;) {
+    /*ssize_t len = read(0, &key, 1);
+    if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
+      continue;
+    } else if (len == 0) {
+      return 0;
+      } else if (len != 1) { abort(); }*/
+
+    debugPrint();
+    key = getch();
+
+    switch(key) {
+    case '+': storeSample(); break;
+    case '0': spiData = 0; triggerByteTransferred(); break;
+    case 'q': return 0;
+    default: spiData = key; triggerByteTransferred(); break;
+    }
+  }
+
+  return 0;
+}