.skip / .space directive, improved dump(), fixes #20

Author: ThomasWaldmann

demo.s

@@ -2,7 +2,7 @@
 
             .text
 
-start:      ld r0, r1, 0    # a comment!
+textstart:  ld r0, r1, 0    # a comment!
             st r0, r1, 0
             add r0, r1, r2
             add r0, r1, 42
@@ -48,9 +48,15 @@ start:      ld r0, r1, 0    # a comment!
             wake
             sleep 1
             halt
-end:
+textend:
 
             .data
+data0:      .skip 4, 0x23
+data1:      .space 4, 0x42
+data2:      .skip 4
+dataend:
 
             .bss
-
+bss0:       .skip 4
+bss1:       .skip 4
+bssend:

esp32_ulp/assemble.py

@@ -10,7 +10,7 @@ class Assembler:
 
     def __init__(self):
         self.symbols = {}
-        self.sections = dict(text=[], data=[], bss=0)
+        self.sections = dict(text=[], data=[])
         self.offsets = dict(text=0, data=0, bss=0)
         self.section = TEXT
 
@@ -56,24 +56,27 @@ def append_section(self, value, expected_section=None):
         s = self.section
         if expected_section is not None and s is not expected_section:
             raise TypeError('only allowed in %s section' % expected_section)
-        if s is TEXT or s is DATA:
+        if s is BSS:
+            # just increase BSS size by value
+            self.offsets[s] += value
+        else:
             self.sections[s].append(value)
             self.offsets[s] += 1
-        elif s is BSS:
-            self.sections[s] += value  # just increase BSS size by value
 
     def dump(self):
         print("Symbols:")
         for label, section_offset in sorted(self.symbols.items()):
             print(label, section_offset)
         print("%s section:" % TEXT)
         for t in self.sections[TEXT]:
-            print(hex(t))
+            print("%08x" % t)
+        print("size: %d" % self.offsets[TEXT])
         print("%s section:" % DATA)
         for d in self.sections[DATA]:
-            print(d)
+            print("%08x" % d)
+        print("size: %d" % self.offsets[DATA])
         print("%s section:" % BSS)
-        print("size: %d" % self.sections[BSS])
+        print("size: %d" % self.offsets[BSS])
 
     def d_text(self):
         self.section = TEXT
@@ -84,6 +87,24 @@ def d_data(self):
     def d_bss(self):
         self.section = BSS
 
+    def d_skip(self, amount, fill=None):
+        # TODO fill should be 8bit, but we are currently filling with 32bit
+        s = self.section
+        amount = int(amount)
+        if fill is not None and s is BSS:
+            raise ValueError('fill not allowed in section %s' % s)
+        fill = int(fill or 0)
+        if amount % 4:
+            amount += 4 - amount % 4
+        amount = amount // 4
+        if s is BSS:
+            self.append_section(amount)
+        else:
+            for i in range(amount):
+                self.append_section(fill)
+
+    d_space = d_skip
+
     def assemble(self, lines):
         for label, opcode, args in self.parse(lines):
             if label is not None:

tests/assemble.py

@@ -44,7 +44,7 @@ def test_assemble():
     assert a.symbols['end'] == (TEXT, 4)
     assert len(a.sections[TEXT]) == 4
     assert len(a.sections[DATA]) == 0
-    assert a.sections[BSS] == 0
+    assert a.offsets[BSS] == 0
 
 
 test_parse_line()