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osmo-codegen
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add some descriptive comments to the grammar definition

This commit is contained in:
Harald Welte 2011-01-11 00:11:43 +01:00
parent 5c8b371145
commit 832889c5e7
1 changed files with 29 additions and 17 deletions
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46
osmo_codegen.g
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@ -6,7 +6,10 @@ grammar osmo_codegen;
root :
(pdu_spec | ie_spec | ie_alias)*
;
/* INFORMATION ELEMENTS */
/* An alias in the form "ie_alias new_name existing_field" */
ie_alias: 'ie_alias' ie_name ie_name;
ie_name : ID;
@ -23,18 +26,27 @@ ie_field_def
ie_field_name
: ID;
ie_field_len
: (NUMERIC | '*');
: (NUMERIC
| '*' // * only permitted in last field, menas 'all remaining octets/bits'
);
ie_field_type
: ('byte' | 'bytes' | 'bit' | 'bits' | 'bcd');
: ('byte' | 'bytes'
| 'bit' | 'bits'
| 'bcd' // BCD digits, always 'lower nibble, upper nibble, lower nibble, ...
);
ie_field_opts
: field_val? ie_field_cond? ie_field_endian?;
ie_field_cond
: 'if (' ie_field_name COMP_OP NUMERIC ')';
: 'if (' ie_field_name ('&' ie_field_cond_mask)? COMP_OP ie_field_cond_reference ')';
ie_field_cond_mask
: NUMERIC;
ie_field_cond_reference
: NUMERIC;
ie_field_endian
: ('big' | 'little');
/* PDU */
/* PDU DEFINITIONS*/
pdu_spec
: 'pdu_spec' ID
@ -46,32 +58,32 @@ pdu_field_mode
: 'mand' | 'opt' | 'cond';
field_val
: ('val'|'value') NUMERIC;
: ('val'|'value') NUMERIC; // Field always has to have indicated value
field_tag
: 'tag' NUMERIC;
: 'tag' NUMERIC; // for tagged fields
pdu_field_size
: NUMERIC ('-' NUMERIC)? ;
: NUMERIC ('-' NUMERIC)? ; // fixed length or range
pdu_field_opts
: pdu_up_downlink | pdu_opt_ie
;
pdu_up_downlink
: 'uplink_only' | 'downlink_only';
: 'uplink_only' | 'downlink_only'; // only valid in uplink or downlink
pdu_opt_ie
: 'ie' ID;
: 'ie' ID; // use speciifed IE definition
pdu_field_type
: (
('V4u' field_val?)
| ('V4l' field_val?)
| ('V' pdu_field_size field_val?)
| ('TLV' pdu_field_size? field_val? field_tag)
| ('LV' pdu_field_size field_val?)
| ('TV' pdu_field_size field_val? field_tag)
| ('T' field_val? field_tag)
| ('TV4' field_val? field_tag)
('V4u' field_val?) // 4 bits in the upper nibble
| ('V4l' field_val?) // 4 bits in the lower nibble
| ('V' pdu_field_size field_val?) // 8bit value-only
| ('TLV' pdu_field_size? field_val? field_tag) // full TLV
| ('LV' pdu_field_size field_val?) // LV without Tag
| ('TV' pdu_field_size field_val? field_tag) // TV with fixed length value
| ('T' field_val? field_tag) // T only
| ('TV4' field_val? field_tag) // T is upper nibble, value lower nibble
) pdu_field_opts*;
pdu_field_def