support offsets on labels

3 files changed, 59 insertions, 6 deletions

diff --git a/format.py b/format.py
index 7798589..9e0ead0 100755
--- a/format.py
+++ b/format.py
@@ -84,8 +84,12 @@ def default_slice(val, hi, lo):
 
     >>> default_slice(('label', 'imm12'), 12, 1)
     ('label[12:1]', 'imm12')
+    >>> default_slice(('label-4', 'imm12'), 12, 1)
+    ('label-4[12:1]', 'imm12')
     >>> default_slice(('label[14:3]', 'imm12'), 12, 1)
     ('label[14:3]', 'imm12')
+    >>> default_slice(('label+4[14:3]', 'imm12'), 12, 1)
+    ('label+4[14:3]', 'imm12')
     >>> default_slice(('label[14:3]', 'imm12', 'extra'), 12, 1)
     ('label[14:3]', 'imm12', 'extra')
     >>> default_slice(('label[31:0]', 'imm12'), 11, 0)
@@ -97,13 +101,12 @@ def default_slice(val, hi, lo):
     if 'hi' not in parsed:
       parsed['hi'] = hi
       parsed['lo'] = lo
-
-    ref = '{label}[{hi}:{lo}]'.format(**parsed)
+    ref = subv.format_reference(parsed)
 
     p_size = parsed['hi'] - parsed['lo'] + 1
-    assert parsed['size'] == p_size, "expected {} bit slice, got {} ({} bit)".format(parsed['size'], ref, p_size)
+    assert parsed['size'] == p_size, "expected {} bit slice, got {} ({} bit)".format(parsed['size'], ref[0], p_size)
 
-    return (ref, *val[1:])
+    return ref
 
 def slice_bit_or_ref(val, hi, lo):
     """ bit.slice but for bitfields and label references.
diff --git a/subv.py b/subv.py
index fae4a3e..4f38988 100644
--- a/subv.py
+++ b/subv.py
@@ -2,7 +2,7 @@ import re
 white = re.compile(r'[ \t\.\n]+')
 hex = re.compile(r'^\-?(0x)?[0-9a-f]+$')
 num = re.compile(r'^\d+$')
-slice_re = re.compile(r'^([^\[]+)(?:\[(\d+):(\d+)\])?$')
+ref_re = re.compile(r'^([^\[+-]+)(?:([+-]\d+))?(?:\[(\d+):(\d+)\])?$')
 field_re = re.compile(r'^(imm|off)(\d+)$')
 
 # parsing
@@ -91,13 +91,22 @@ def parse_reference(part):
     >>> parse_reference(('lbl', 'imm32'))
     {'label': 'lbl', 'mode': 'imm', 'size': 32, 'meta': ()}
 
+    >>> parse_reference(('lbl+0', 'imm32'))
+    {'label': 'lbl', 'mode': 'imm', 'size': 32, 'meta': (), 'offset': 0}
+
+    >>> parse_reference(('lbl+2', 'imm32'))
+    {'label': 'lbl', 'mode': 'imm', 'size': 32, 'meta': (), 'offset': 2}
+
     >>> parse_reference(('x[11:0]', 'off12'))
     {'label': 'x', 'mode': 'off', 'size': 12, 'meta': (), 'hi': 11, 'lo': 0}
+
+    >>> parse_reference(('x-16[11:0]', 'off12'))
+    {'label': 'x', 'mode': 'off', 'size': 12, 'meta': (), 'offset': -16, 'hi': 11, 'lo': 0}
     """
     ref = part[0]
     field = part[1]
 
-    label, hi, lo = slice_re.match(ref).groups()
+    label, off, hi, lo = ref_re.match(ref).groups()
     mode, size = field_re.match(field).groups()
     
     ref = {
@@ -107,6 +116,9 @@ def parse_reference(part):
         'meta': part[2:],
     }
 
+    if off is not None:
+        ref['offset'] = int(off)
+
     if hi is not None:
         ref['hi'] = int(hi)
         ref['lo'] = int(lo)
@@ -177,12 +189,18 @@ def is_reference(part):
     True
     >>> is_reference(('hello:world',))
     True
+    >>> is_reference(('hello-4',))
+    True
+    >>> is_reference(('hello[11:0]',))
+    True
     >>> is_reference(('$label',))
     True
     >>> is_reference(('$label:extra',))
     True
     >>> is_reference(('$label:extra', 'off20'))
     True
+    >>> is_reference(('$label+3[31:12]', 'off20'))
+    True
     >>> is_reference(('plain', 'off20'))
     True
 
@@ -225,6 +243,29 @@ def untag(part, expect=None):
         raise ValueError("expected {} to be labelled {}".format(part, expect))
     return part[0]
 
+def format_reference(ref):
+    """ opposite of parse_reference..
+
+    >>> format_reference({'label': 'lbl', 'mode': 'imm', 'size': 32, 'meta': ()})
+    ('lbl', 'imm32')
+    >>> format_reference({'label': 'lbl', 'offset': 0, 'mode': 'imm', 'size': 32, 'meta': ()})
+    ('lbl+0', 'imm32')
+    >>> format_reference({'label': 'lbl', 'offset': 2, 'mode': 'imm', 'size': 32, 'meta': ()})
+    ('lbl+2', 'imm32')
+    >>> format_reference({'label': 'x', 'mode': 'off', 'size': 12, 'meta': (), 'hi': 11, 'lo': 0})
+    ('x[11:0]', 'off12')
+    >>> format_reference({'label': 'x', 'offset': -16, 'mode': 'off', 'size': 12, 'meta': (), 'hi': 11, 'lo': 0})
+    ('x-16[11:0]', 'off12')
+    >>> format_reference({'label': 'x', 'offset': -16, 'mode': 'off', 'size': 12, 'meta': ('extra', 'stuff'), 'hi': 11, 'lo': 0})
+    ('x-16[11:0]', 'off12', 'extra', 'stuff')
+    """
+    label = ref['label']
+    if 'offset' in ref:
+        label += '{:+}'.format(ref['offset'])
+    if 'hi' in ref:
+        label += '[{hi}:{lo}]'.format(**ref)
+    return (label, '{mode}{size}'.format(**ref), *ref['meta'])
+
 def format_part(part):
     """ opposite of parse_part.
 
diff --git a/survey.py b/survey.py
index f8df47d..55a8ab0 100755
--- a/survey.py
+++ b/survey.py
@@ -60,6 +60,8 @@ def observe(part, rel_addr, map):
     (3, '3')
     >>> observe(('label[31:0]', 'imm32'), 0, {'label': 1234})
     (1234, 32)
+    >>> observe(('label-2[31:0]', 'imm32'), 0, {'label': 1234})
+    (1232, 32)
     >>> observe(('label[1:0]', 'imm32'), 0, {'label': 1234})
     (2, 2)
     >>> observe(('label[31:0]', 'off32'), 1000, {'label': 1234})
@@ -68,6 +70,10 @@ def observe(part, rel_addr, map):
     (16, 20)
     >>> observe(('label[31:0]', 'off32'), 2000, {'label': 1000})
     (4294966296, 32)
+    >>> observe(('label+4[7:0]', 'off32'), 0x1000, {'label': 0x1234})
+    (56, 8)
+    >>> observe(('label+4[15:8]', 'off32'), 0x1000, {'label': 0x1234})
+    (2, 8)
 
     >>> observe(('label[32:0]', 'imm32'), 0, {})
     Traceback (most recent call last):
@@ -81,6 +87,9 @@ def observe(part, rel_addr, map):
     assert ref['label'] in map, "undefined label '{}'".format(ref['label'])
     addr = map[ref['label']]
 
+    if 'offset' in ref:
+        addr += ref['offset']
+
     # @TODO: the hardcoded 32 here is not right, this is going to blow up
     # in some circumstances (e.g. a backwards branch 2<<18 bytes away)
     if ref['mode'] == 'imm':