From 9e84306a949cde6476f23c0a0f6b172f120b082d Mon Sep 17 00:00:00 2001
From: "Edward V. Emelianov" <eddy@sao.ru>
Date: Mon, 9 Feb 2026 22:00:51 +0300
Subject: [PATCH] poll test works @high speed

---
 LibSidServo/polltest/main.c | 102 +++++++++++-------------------------
 1 file changed, 31 insertions(+), 71 deletions(-)

diff --git a/LibSidServo/polltest/main.c b/LibSidServo/polltest/main.c
index b67ad0e..6ac84db 100644
--- a/LibSidServo/polltest/main.c
+++ b/LibSidServo/polltest/main.c
@@ -24,7 +24,8 @@
 #include <sys/ioctl.h>
 #include <usefull_macros.h>
 
-#define XYBUFSZ     (2048)
+// suppose that we ONLY poll data
+#define XYBUFSZ     (128)
 
 struct{
     int help;
@@ -79,66 +80,29 @@ static int op(const char *nm){
     return fd;
 }
 
-static int eolcnt(buf_t *buf){
-    if(!buf) return -1;
-    int cnt = 0;
-    for(int i = 0; i < buf->len; ++i)
-        if(buf->buf[i] == '\n') ++cnt;
-    return cnt;
-}
-// move last record (if any) into head of buffer
-static void movelast(buf_t *buf){
-    FNAME();
-    if(!buf) return;
-    DBG("buf was: %s", buf->buf);
-    int cnt = eolcnt(buf);
-    char *E = strrchr(buf->buf, '\n');
-    int idx = -1;
-    if(E){
-        idx = ++E - buf->buf; // position of symbol after '\n'
-    }else{
-        buf->len = strlen(buf->buf);
-        DBG("leave as is (%s)", buf->buf);
-        return;
-    }
-    DBG("cnt=%d, idx=%d", cnt, idx);
-    switch(cnt){
-        case 0: // EOL not found - clear buf
-            buf->len = 0;
-        break;
-        case 1: // only one record - move all after '\n'
-            if(idx > 0 && idx < XYBUFSZ){
-                buf->len = XYBUFSZ - idx;
-                memmove(buf->buf, E, buf->len);
-            }else buf->len = 0;
-        break;
-        default: // more than one record - move
-        {
-            int i = idx - 2;
-            for(; i > -1; --i)
-                if(buf->buf[i] == '\n') break;
-            ++i;
-            buf->len = XYBUFSZ - i;
-            memmove(buf->buf, &buf->buf[i], buf->len);
-        }
-    }
-    buf->buf[buf->len] = 0;
-    DBG("MOVED; now buf[%d]=%s", buf->len, buf->buf);
-}
 // write to buffer next data portion; return FALSE in case of error
 static int readstrings(buf_t *buf, int fd){
+    FNAME();
     if(!buf){WARNX("Empty buffer"); return FALSE;}
     int L = XYBUFSZ - buf->len;
     if(L == 0){
-        DBG("len: %d", buf->len);
-        movelast(buf);
+        DBG("buffer  overfull!", buf->len);
+        char *lastn = strrchr(buf->buf, '\n');
+        if(lastn){
+            fprintf(stderr, "BUFOVR: _%s_", buf->buf);
+            ++lastn;
+            buf->len = XYBUFSZ - (lastn - buf->buf);
+            DBG("Memmove %d", buf->len);
+            memmove(lastn, buf->buf, buf->len);
+            buf->buf[buf->len] = 0;
+        }else buf->len = 0;
         L = XYBUFSZ - buf->len;
     }
     int got = read(fd, &buf->buf[buf->len], L);
     if(got < 0){
         WARN("read()");
         return FALSE;
-    }else if(got == 0) return TRUE;
+    }else if(got == 0){ DBG("NO data"); return TRUE; }
     buf->len += got;
     buf->buf[buf->len] = 0;
     DBG("buf[%d]: %s", buf->len, buf->buf);
@@ -146,28 +110,22 @@ static int readstrings(buf_t *buf, int fd){
 }
 // return TRUE if got, FALSE if no data found
 static int getdata(buf_t *buf, long *out){
-    if(!buf) return -1;
+    if(!buf || buf->len < 1) return FALSE;
     // read record between last '\n' and previous (or start of string)
-    int cnt = eolcnt(buf);
-    if(cnt < 1) return FALSE;
-    char *last = strrchr(buf->buf, '\n');
-    if(!last) return FALSE; // WTF?
+    char *last = &buf->buf[buf->len - 1];
+    //DBG("buf: _%s_", buf->buf);
+    if(*last != '\n') return FALSE;
     *last = 0;
-    char *prev = buf->buf;
-    if(cnt > 1) prev = strrchr(buf->buf, '\n') + 1;
-    if(!prev) prev = buf->buf; // ??
-    if(out) *out = atol(prev);
-    int l = strlen(++last);
-    if(l < XYBUFSZ){
-        buf->len = l;
-        if(l){
-            memmove(buf->buf, last, l);
-            DBG("moved: %s", buf->buf);
-        }else DBG("empty line");
-    }else{
-        buf->len = 0;
-        DBG("buffer clear");
+    //DBG("buf: _%s_", buf->buf);
+    char *prev = strrchr(buf->buf, '\n');
+    if(!prev) prev = buf->buf;
+    else{
+        fprintf(stderr, "MORETHANONE: _%s_", buf->buf);
+        ++prev; // after last '\n'
     }
+    if(out) *out = atol(prev);
+    // clear buffer
+    buf->len = 0;
     return TRUE;
 }
 // try to write '\n' asking new data portion; return FALSE if failed
@@ -177,7 +135,7 @@ static int asknext(int fd){
     int i = 0;
     for(; i < 5; ++i){
         int l = write(fd, "\n", 1);
-        DBG("l=%d", l);
+        //DBG("l=%d", l);
         if(1 == l) return TRUE;
         usleep(100);
     }
@@ -204,14 +162,16 @@ int main(int argc, char **argv){
     t0x = t0y = tstart = sl_dtime();
     DBG("Start");
     do{ // main cycle
-        if(poll(pfds, 2, 1) < 0){
+        if(poll(pfds, 2, 0) < 0){
             WARN("poll()");
             break;
         }
         if(pfds[0].revents && POLLIN){
+            DBG("got X");
             if(!readstrings(&xbuf, Xfd)) break;
         }
         if(pfds[1].revents && POLLIN){
+            DBG("got Y");
             if(!readstrings(&ybuf, Yfd)) break;
         }
         double curt = sl_dtime();