From db67a6922b9c20c4be792f06772780f6ae30eb2d Mon Sep 17 00:00:00 2001
From: Martin Peach <mrpeach@users.sourceforge.net>
Date: Mon, 3 May 2010 23:24:54 +0000
Subject: [slipdec] decodes an input list of bytes-as-floats assuming they were
 encoded using SLIP. Useful for OSC over serial links.

svn path=/trunk/externals/mrpeach/; revision=13488
---
 slipdec/slipdec.c | 106 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 slipdec/slipdec.c

diff --git a/slipdec/slipdec.c b/slipdec/slipdec.c
new file mode 100644
index 0000000..c38cd20
--- /dev/null
+++ b/slipdec/slipdec.c
@@ -0,0 +1,106 @@
+/* slipdec.c 20070711 Martin Peach */
+/* decode a list of SLIP-encoded bytes */
+#include "m_pd.h" 
+
+/* -------------------------- slipdec -------------------------- */
+#ifndef _SLIPCODES
+/* SLIP special character codes */
+#define SLIP_END     0300 /* indicates end of packet */
+#define SLIP_ESC     0333 /* indicates byte stuffing */
+#define SLIP_ESC_END 0334 /* SLIP_ESC SLIP_ESC_END means SLIP_END data byte */
+#define SLIP_ESC_ESC 0335 /* SLIP_ESC SLIP_ESC_ESC means SLIP_ESC data byte */
+#define MAX_SLIP 1006 /* maximum SLIP packet size */
+#define _SLIPCODES
+#endif // _SLIPCODES
+
+static t_class *slipdec_class;
+
+typedef struct _slipdec
+{
+    t_object    x_obj;
+    t_outlet    *x_slipdec_out;
+    t_atom      *x_slip_buf;
+    t_int       x_slip_length;
+} t_slipdec;
+
+static void *slipdec_new(t_symbol *s, int argc, t_atom *argv);
+static void slipdec_list(t_slipdec *x, t_symbol *s, int ac, t_atom *av);
+static void slipdec_free(t_slipdec *x);
+void slipdec_setup(void);
+
+static void *slipdec_new(t_symbol *s, int argc, t_atom *argv)
+{
+    int i;
+    t_slipdec  *x = (t_slipdec *)pd_new(slipdec_class);
+
+    x->x_slip_buf = (t_atom *)getbytes(sizeof(t_atom)*MAX_SLIP);
+    if(x->x_slip_buf == NULL)
+    {
+        error("slipdec: unable to allocate %lu bytes for x_slip_buf", (long)sizeof(t_atom)*MAX_SLIP);
+        return NULL;
+    }
+    else post("slipdec: allocated %lu bytes for x_slip_buf", (long)sizeof(t_atom)*MAX_SLIP);
+    /* init the slip buf atoms to float type */
+    for (i = 0; i < MAX_SLIP; ++i) x->x_slip_buf[i].a_type = A_FLOAT;
+    x->x_slipdec_out = outlet_new(&x->x_obj, &s_list);
+    return (x);
+}
+
+static void slipdec_list(t_slipdec *x, t_symbol *s, int ac, t_atom *av)
+{
+    /* SLIP decode a list of bytes */
+    float   f;
+    int     i, c, esced = 0;
+
+    /* for each byte in the packet, send the appropriate character sequence */
+    for(i = x->x_slip_length = 0; ((i < ac) && (x->x_slip_length < MAX_SLIP)); ++i)
+    {
+        /* check each atom for byteness */
+        f = atom_getfloat(&av[i]);
+        c = (((int)f) & 0x0FF);
+        if (c != f)
+        {
+            /* abort, bad input character */
+            pd_error (x, "slipdec: input %d out of range [0..255]", f);
+            return;
+        }
+        if(SLIP_END == c)
+        {
+            /* If it's the beginning of a packet, ignore it */
+            if (0 == i) continue;
+            /* send the packet */
+            else break;
+        }
+        if (SLIP_ESC == c)
+        {
+            esced = 1;
+            continue;
+        }
+        if (0 != esced)
+        {
+            if (SLIP_ESC_END == c) c = SLIP_END;
+            else if (SLIP_ESC_ESC == c) c = SLIP_ESC;
+            esced = 0;
+        }
+        /* Add the character to the list */
+        x->x_slip_buf[x->x_slip_length++].a_w.w_float = c;
+    }
+    if (0 != x->x_slip_length)
+        outlet_list(x->x_slipdec_out, &s_list, x->x_slip_length, x->x_slip_buf);
+}
+
+static void slipdec_free(t_slipdec *x)
+{
+    if (x->x_slip_buf != NULL) freebytes((void *)x->x_slip_buf, sizeof(t_atom)*MAX_SLIP);
+}
+
+void slipdec_setup(void)
+{
+    slipdec_class = class_new(gensym("slipdec"), 
+        (t_newmethod)slipdec_new, (t_method)slipdec_free,
+        sizeof(t_slipdec), 0, A_GIMME, 0);
+    class_addlist(slipdec_class, slipdec_list);
+    class_sethelpsymbol(slipdec_class, gensym("slipenc")); /* use slipenc-help.pd */
+}
+
+/* fin slipdec.c*/
-- 
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