Upgrade bitfile parser to use a reader object

Author: patrislav1

bin2hpm/bitfile.py

@@ -6,52 +6,59 @@
 
 import sys
 
-def bs_read_n(inp, n):
-    result, inp = \
-        int.from_bytes(inp[0:n], byteorder='big'), inp[n:]
-    return result, inp
+class BitfileReader():
+    def __init__(self, input):
+        self.inp = input
+    
+    def read_n(self, n):
+        val, self.inp = self.inp[:n], self.inp[n:]
+        return val
 
-def bs_read_u8(inp):
-    return bs_read_n(inp, 1)
+    def read_int(self, n):
+        result, self.inp = \
+            int.from_bytes(self.inp[0:n], byteorder='big'), self.inp[n:]
+        return result
 
-def bs_read_u16(inp):
-    return bs_read_n(inp, 2)
+    def read_u8(self):
+        return self.read_int(1)
 
-def bs_read_u32(inp):
-    return bs_read_n(inp, 4)
+    def read_u16(self):
+        return self.read_int(2)
 
-def bs_read_str(inp):
-    n, inp = bs_read_u16(inp)
-    val, inp = inp[:n], inp[n:]
-    return val, inp
+    def read_u32(self):
+        return self.read_int(4)
 
-def check_info(inp, section_expected, title):
-    section_name, inp = bs_read_u8(inp)
+    def read_str(self):
+        n = self.read_u16()
+        return self.read_n(n)
+
+def check_info(bs, section_expected, title):
+    section_name = bs.read_u8()
     if section_name != ord(section_expected):
         raise ValueError(f'Bitstream section {section_expected} missing')
 
-    section_info, inp = bs_read_str(inp)
+    section_info = bs.read_str()
     section_info = section_info.decode('utf-8')
     print(f'{title}: {section_info}')
-    return inp
 
 def parse_bitfile(inp):
     print('Parsing bitfile...')
-    prologue, inp = bs_read_str(inp)
-    one, inp = bs_read_u16(inp)
+    bs = BitfileReader(inp)
+    prologue = bs.read_str()
+    one = bs.read_u16()
     if len(prologue) != 9 or one != 1:
         raise ValueError('Bitstream header invalid')
 
-    inp = check_info(inp, 'a', ' Design info')
-    inp = check_info(inp, 'b', '   Part name')
-    inp = check_info(inp, 'c', '   File date')
-    inp = check_info(inp, 'd', '        time')
+    check_info(bs, 'a', ' Design info')
+    check_info(bs, 'b', '   Part name')
+    check_info(bs, 'c', '   File date')
+    check_info(bs, 'd', '        time')
 
-    section_e, inp = bs_read_u8(inp)
+    section_e = bs.read_u8()
     if section_e != ord('e'):
         raise ValueError('Bitstream section e missing')
 
-    payload_size, inp = bs_read_u32(inp)
+    payload_size = bs.read_u32()
     print(f'  Image size: 0x{payload_size:08x} ({int(payload_size/1024)}KiB)\n')
 
-    return inp[:payload_size]
+    return bs.read_n(payload_size)