From c8e1e71eb526475dd431443345262c2e5a627831 Mon Sep 17 00:00:00 2001
From: Nicholas Noll <nnoll523@gmail.com>
Date: Sat, 23 Oct 2021 11:17:25 -0700
Subject: chore(rename): libn -> base

---
 sys/base/bufio.c | 190 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 190 insertions(+)
 create mode 100644 sys/base/bufio.c

(limited to 'sys/base/bufio.c')

diff --git a/sys/base/bufio.c b/sys/base/bufio.c
new file mode 100644
index 0000000..7ebee68
--- /dev/null
+++ b/sys/base/bufio.c
@@ -0,0 +1,190 @@
+#include <u.h>
+#include <base.h>
+
+// -----------------------------------------------------------------------
+// reader
+
+error
+bufio·initreader(io·Buffer *buf, io·Reader rdr, void *h)
+{
+    if (buf->state) {
+        errorf("attemped to initialize an active buffer, state is '%d'", buf->state);
+        return bufio·err;
+    }
+    buf->state    = bufio·rdr;
+    buf->runesize = 0;
+    buf->h        = h;
+    buf->rdr      = rdr;
+    buf->beg      = buf->buf + bufio·ungets;
+    buf->pos      = buf->beg;
+    buf->end      = buf->pos; 
+    buf->size     = bufio·size - bufio·ungets;
+
+    return 0;
+}
+
+void
+bufio·finireader(io·Buffer *buf)
+{
+    buf->state    = bufio·nil;
+    buf->runesize = 0;
+    buf->rdr      = (io·Reader){ .read = nil };
+}
+
+static
+int
+refill(io·Buffer *buf)
+{
+    int n;
+
+    if (buf->state & bufio·end) {
+        return bufio·err;
+    }
+    memcpy(buf->buf, buf->pos - bufio·ungets, bufio·ungets);
+
+    n = buf->rdr.read(buf->h, 1, buf->size, buf->beg);
+    if (n < 0) 
+        return bufio·err;
+    if (n == 0) {
+        buf->state |= bufio·end;
+        return 0;
+    }
+
+    buf->pos = buf->beg;
+    buf->end = buf->pos + n;
+
+    // TEST: put a physical EOF byte at the end
+    // this would allow for an unget operation
+    if (n < buf->size)
+        *buf->end++ =  EOF;
+
+    return n;
+}
+
+int
+bufio·getbyte(io·Buffer *buf)
+{
+getbyte:
+    if (buf->pos < buf->end) {
+        return *buf->pos++;
+    }
+
+    memmove(buf->buf, buf->end - bufio·ungets, bufio·ungets);
+
+    if (refill(buf) <= 0)
+        return bufio·eof;
+
+    goto getbyte;
+}
+
+error
+bufio·ungetbyte(io·Buffer *buf, byte c)
+{
+    if (!(buf->state & bufio·rdr)) {
+        errorf("attempted to unget on non-active reader");
+        return bufio·err;
+    }
+
+    if (buf->pos == buf->buf) {
+        errorf("attempted to unget past end of buffer");
+        return bufio·err;
+    }
+
+    buf->pos--;
+    return 0;
+}
+
+rune
+bufio·getrune(io·Buffer *buf)
+{
+    ubyte b;
+    int   i;
+    byte  str[UTFmax+1];
+    rune  r;
+
+    // NOTE: I'm worried about the sign here...
+    b = bufio·getbyte(buf);
+    if (b < RuneSelf) {
+        buf->runesize = 1;
+        return b;
+    }
+
+    i = 0;
+    str[i++] = b;
+
+nextbyte:
+    b = bufio·getbyte(buf);
+    if (b < 0)            return b;
+    if (i >= arrlen(str)) return RuneErr;
+    str[i++] = b;
+    if (!utf8·fullrune(str, i))
+        goto nextbyte;
+
+    buf->runesize = utf8·bytetorune(&r, str);
+    if (r == RuneErr && b == 1) {
+        errorf("illegal UTF-8 sequence");
+		for (; i >= 0; i--)
+			errorf("%s%.2x", i > 0 ? " " : "", *(ubyte*)(str+i));
+		errorf("\n");
+
+        buf->runesize = 0;
+    } else
+        for (; i > buf->runesize; i--)
+            bufio·ungetbyte(buf, str[i]);
+
+    return r;
+}
+
+// TODO: Check that we are given the correct rune!
+error
+bufio·ungetrune(io·Buffer *buf, rune r)
+{
+    if (buf->state & bufio·rdr) {
+        errorf("attempted to unget on non-active reader");
+        return bufio·err;
+    }
+
+    if (buf->pos == buf->buf) {
+        errorf("attempted to unget past end of buffer");
+        return bufio·err;
+    }
+
+    buf->pos -= buf->runesize;
+    return 0;
+}
+
+int
+bufio·read(io·Buffer *buf, int sz, int n, void *out)
+{
+    byte *wtr;
+    int   nr, rem, diff;
+
+    if (n == 0 || buf->state & bufio·end) 
+        return bufio·err;
+
+    assert(buf->state & bufio·rdr);
+
+    wtr = out;
+    rem = n*sz;
+    while (rem > 0) {
+        diff = buf->end - buf->pos;
+        nr   = MIN(diff, rem);
+        if (!nr) {
+            if (buf->state & bufio·end) 
+                break;
+            if (refill(buf) <= 0)
+                break;
+
+            continue;
+        }
+        memmove(wtr, buf->pos, nr);
+        wtr      += nr;
+        buf->pos += nr;
+        rem      -= nr;
+    }
+
+    return n - rem/sz;
+}
+
+// -----------------------------------------------------------------------
+// writer
-- 
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