From beb2c8145358bcd7b4494a7b636e378aa2a1ea95 Mon Sep 17 00:00:00 2001 From: Martin Peach Date: Wed, 15 Sep 2010 18:52:38 +0000 Subject: Can set maximum packet length. Updated help patch. svn path=/trunk/externals/mrpeach/; revision=14147 --- slipenc/slipenc.c | 180 ++++++++++++++++++++++++++++++------------------------ 1 file changed, 101 insertions(+), 79 deletions(-) (limited to 'slipenc/slipenc.c') diff --git a/slipenc/slipenc.c b/slipenc/slipenc.c index 814b5cd..74b1b29 100644 --- a/slipenc/slipenc.c +++ b/slipenc/slipenc.c @@ -1,38 +1,37 @@ -/* slipenc.c 20070711 Martin Peach */ -/**encode a list of bytes as SLIP / +/* slipenc.c 20100513 Martin Peach */ +/* encode a list of bytes as SLIP */ /* -/* -From RFC 1055: -PROTOCOL - - The SLIP protocol defines two special characters: SLIP_END and SLIP_ESC. SLIP_END is - octal 300 (decimal 192) and SLIP_ESC is octal 333 (decimal 219) not to be - confused with the ASCII ESCape character; for the purposes of this - discussion, SLIP_ESC will indicate the SLIP SLIP_ESC character. To send a - packet, a SLIP host simply starts sending the data in the packet. If - a data byte is the same code as SLIP_END character, a two byte sequence of - SLIP_ESC and octal 334 (decimal 220) is sent instead. If it the same as - an SLIP_ESC character, an two byte sequence of SLIP_ESC and octal 335 (decimal - 221) is sent instead. When the last byte in the packet has been - sent, an SLIP_END character is then transmitted. - - Phil Karn suggests a simple change to the algorithm, which is to - begin as well as end packets with an SLIP_END character. This will flush - any erroneous bytes which have been caused by line noise. In the - normal case, the receiver will simply see two back-to-back SLIP_END - characters, which will generate a bad IP packet. If the SLIP - implementation does not throw away the zero-length IP packet, the IP - implementation certainly will. If there was line noise, the data - received due to it will be discarded without affecting the following - packet. - - Because there is no 'standard' SLIP specification, there is no real - defined maximum packet size for SLIP. It is probably best to accept - the maximum packet size used by the Berkeley UNIX SLIP drivers: 1006 - bytes including the IP and transport protocol headers (not including - the framing characters). Therefore any new SLIP implementations - should be prepared to accept 1006 byte datagrams and should not send - more than 1006 bytes in a datagram. +* From RFC 1055: +* PROTOCOL +* +* The SLIP protocol defines two special characters: SLIP_END and SLIP_ESC. SLIP_END is +* octal 300 (decimal 192) and SLIP_ESC is octal 333 (decimal 219) not to be +* confused with the ASCII ESCape character; for the purposes of this +* discussion, SLIP_ESC will indicate the SLIP SLIP_ESC character. To send a +* packet, a SLIP host simply starts sending the data in the packet. If +* a data byte is the same code as SLIP_END character, a two byte sequence of +* SLIP_ESC and octal 334 (decimal 220) is sent instead. If it the same as +* an SLIP_ESC character, an two byte sequence of SLIP_ESC and octal 335 (decimal +* 221) is sent instead. When the last byte in the packet has been +* sent, an SLIP_END character is then transmitted. +* +* Phil Karn suggests a simple change to the algorithm, which is to +* begin as well as end packets with an SLIP_END character. This will flush +* any erroneous bytes which have been caused by line noise. In the +* normal case, the receiver will simply see two back-to-back SLIP_END +* characters, which will generate a bad IP packet. If the SLIP +* implementation does not throw away the zero-length IP packet, the IP +* implementation certainly will. If there was line noise, the data +* received due to it will be discarded without affecting the following +* packet. +* +* Because there is no 'standard' SLIP specification, there is no real +* defined maximum packet size for SLIP. It is probably best to accept +* the maximum packet size used by the Berkeley UNIX SLIP drivers: 1006 +* bytes including the IP and transport protocol headers (not including +* the framing characters). Therefore any new SLIP implementations +* should be prepared to accept 1006 byte datagrams and should not send +* more than 1006 bytes in a datagram. */ #include "m_pd.h" @@ -40,11 +39,11 @@ PROTOCOL /* -------------------------- slipenc -------------------------- */ #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 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 @@ -56,6 +55,7 @@ typedef struct _slipenc t_outlet *x_slipenc_out; t_atom *x_slip_buf; t_int x_slip_length; + t_int x_slip_max_length; } t_slipenc; static void *slipenc_new(t_symbol *s, int argc, t_atom *argv); @@ -65,17 +65,35 @@ void slipenc_setup(void); static void *slipenc_new(t_symbol *s, int argc, t_atom *argv) { - int i; + int i, max_len; t_slipenc *x = (t_slipenc *)pd_new(slipenc_class); - x->x_slip_buf = (t_atom *)getbytes(sizeof(t_atom)*MAX_SLIP); + if (x == NULL) return x; + + x->x_slip_max_length = MAX_SLIP; // default unless float argument given + for (i = 0; i < argc; ++i) + { + if (argv[i].a_type == A_FLOAT) + { + max_len = atom_getfloat(&argv[i]); + if (max_len > 3) + { + x->x_slip_max_length = max_len; + post("slipenc: maximum packet length is %d", x->x_slip_max_length); + } + else + post("slipenc: maximum packet length must be greater than 3, using %d", x->x_slip_max_length); + break; + } + } + x->x_slip_buf = (t_atom *)getbytes(sizeof(t_atom)*x->x_slip_max_length); if(x->x_slip_buf == NULL) { - error("slipenc: unable to allocate %lu bytes for x_slip_buf", (long)sizeof(t_atom)*MAX_SLIP); + error("slipenc: unable to allocate %lu bytes for x_slip_buf", (long)sizeof(t_atom)*x->x_slip_max_length); return NULL; } /* Initialize all the slip buf atoms to float type */ - for (i = 0; i < MAX_SLIP; ++i) x->x_slip_buf[i].a_type = A_FLOAT; + for (i = 0; i < x->x_slip_max_length; ++i) x->x_slip_buf[i].a_type = A_FLOAT; x->x_slipenc_out = outlet_new(&x->x_obj, &s_list); return (x); } @@ -86,51 +104,55 @@ static void slipenc_list(t_slipenc *x, t_symbol *s, int ac, t_atom *av) float f; int i, c; - i = x->x_slip_length = 0; - /* send an initial SLIP_END character to flush out any data that may */ - /* have accumulated in the receiver due to line noise */ - x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_END; - + i = 0; /* for each byte in the packet, send the appropriate character sequence */ - while((i < ac) && (x->x_slip_length < (MAX_SLIP-1))) + while (i < ac) { - /* check each atom for byteness */ - f = atom_getfloat(&av[i++]); - c = (((int)f) & 0x0FF); - if (c != f) - { - /* abort, bad input character */ - pd_error (x, "slipenc: input %f out of range [0..255]", f); - return; - } - if(SLIP_END == c) - { - /* If it's the same code as a SLIP_END character, replace it with a */ - /* special two-character code so as not to make the receiver think we sent SLIP_END */ - x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_ESC; - x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_ESC_END; - } - else if (SLIP_ESC == c) - { - /* If it's the same code as a SLIP_ESC character, replace it with a special two-character code */ - /* so as not to make the receiver think we sent SLIP_ESC */ - x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_ESC; - x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_ESC_ESC; - } - else + x->x_slip_length = 0; + /* send an initial SLIP_END character to flush out any data that may */ + /* have accumulated in the receiver due to line noise */ + x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_END; + + while((i < ac)&&(x->x_slip_length < (x->x_slip_max_length-2))) { - /* Otherwise, pass the character */ - x->x_slip_buf[x->x_slip_length++].a_w.w_float = c; + /* check each atom for byteness */ + f = atom_getfloat(&av[i++]); + c = (((int)f) & 0x0FF); + if (c != f) + { + /* abort, bad input character */ + pd_error (x, "slipenc: input %f out of range [0..255]", f); + return; + } + if(SLIP_END == c) + { + /* If it's the same code as a SLIP_END character, replace it with a */ + /* special two-character code so as not to make the receiver think we sent SLIP_END */ + x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_ESC; + x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_ESC_END; + } + else if (SLIP_ESC == c) + { + /* If it's the same code as a SLIP_ESC character, replace it with a special two-character code */ + /* so as not to make the receiver think we sent SLIP_ESC */ + x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_ESC; + x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_ESC_ESC; + } + else + { + /* Otherwise, pass the character */ + x->x_slip_buf[x->x_slip_length++].a_w.w_float = c; + } } + /* Add the SLIP_END code to tell the receiver that the packet is complete */ + x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_END; + outlet_list(x->x_slipenc_out, &s_list, x->x_slip_length, x->x_slip_buf); } - /* Add the SLIP_END code to tell the receiver that the packet is complete */ - x->x_slip_buf[x->x_slip_length++].a_w.w_float = SLIP_END; - outlet_list(x->x_slipenc_out, &s_list, x->x_slip_length, x->x_slip_buf); } static void slipenc_free(t_slipenc *x) { - if (x->x_slip_buf != NULL) freebytes((void *)x->x_slip_buf, sizeof(t_atom)*MAX_SLIP); + if (x->x_slip_buf != NULL) freebytes((void *)x->x_slip_buf, sizeof(t_atom)*x->x_slip_max_length); } void slipenc_setup(void) -- cgit v1.2.1