Feat: added buffered io from plan9

As we no longer have the FILE type, we need to buffer our reading and
writing so that we don't have to make so many syscalls. The API is nice
so that we can buffer other readers. We will update it so that it eats
io·Readers/io·Writers.

1 files changed, 45 insertions, 0 deletions

diff --git a/src/base/bufio/getc.c b/src/base/bufio/getc.c
new file mode 100644
index 0000000..264e01d
--- /dev/null
+++ b/src/base/bufio/getc.c
@@ -0,0 +1,45 @@
+#include "internal.h"
+
+int
+bio·getc(io·Header *io)
+{
+    int i;
+    intptr nr;
+
+loop:
+    i = io->ilen;
+    if(i != 0){
+        io->ilen = i+1;
+        return io->e[i];
+    }
+
+    if(io->state != io·BufRdr){
+        if(io->state == io·BufEnd)
+            io->state = io·BufRdr;
+        return io·BufEof;
+    }
+
+    /*
+     * get next buffer, try to keep io·BufUngets bytes
+     * pre-catenated from the previous read to allow for ungets 
+     */
+    mem·move(io->b-io·BufUngets, io->e-io·BufUngets, io·BufUngets);
+    if(sys·read(io->fd, io->cap, io->b, &nr)){
+        io->state = io·BufNil;
+        return io·BufEof;
+    }
+    if(nr == 0){
+        io->state = io·BufEnd;
+        return io·BufEof;
+    }
+
+    if(nr < io->cap){
+        mem·move(io->e-i-io·BufUngets, io->b-io·BufUngets, i+io·BufUngets);
+        io->g = io->e-i;
+    }
+
+    io->ilen = -i;
+    io->pos += +i;
+
+    goto loop;
+}