提交: b5e4f452f17581fdc39d0dc4a09daf6643b88681 - em_gb_asm (git)

Emily's Z80 assembler for the Gameboy.

Commit MetaInfo

• 修訂: b5e4f452f17581fdc39d0dc4a09daf6643b88681 (tree)
• 時間: 2021-02-09 11:46:58
• 作者: AlaskanEmily <emily@alas...>
• Commiter: AlaskanEmily

Log Message

Add relative addressing for jr opcodes

Change Summary

• modified: em_gb_asm.py

差異

--- a/em_gb_asm.py
+++ b/em_gb_asm.py
@@ -116,6 +116,10 @@ class Block:
         self._pushReloc(l, self.relocs8l)
         self.pushByte(0)
     
+    def pushRelocRel(self, l):
+        self._pushReloc(l, self.relocsRel)
+        self.pushByte(0)
+    
     def pushASCII(self, s):
         self.ascii.append((len(self.data), len(s)))
         for c in s:
@@ -151,6 +155,15 @@ class Block:
             for addr in self.relocs8l[l]:
                 dest = self.resolveReloc(l, addr, all_blocks)
                 self.data[addr] = dest & 0xFF
+        for l in self.relocsRel:
+            for addr in self.relocsRel[l]:
+                dest = self.resolveReloc(l, addr, all_blocks) - 1
+                # Validate the distance...
+                abs_addr = self.base + addr
+                if dest - 128 > abs_addr or dest + 127 < abs_addr:
+                    self.error("Relative jump is too far")
+                else:
+                    self.data[addr] = (dest - abs_addr) & 0xFF
     
     def evalBinop(self, expr, i, oplist, func):
         i, val = func(self, expr, i)
@@ -294,7 +307,12 @@ SOME_ARGS = {
         "l":0x85,
         "(hl)":0x86,
         "a":0x87,
-        "hl":{ "sp":0x39 },
+        "hl":{
+            "bc":0x09,
+            "de":0x19,
+            "hl":0x29,
+            "sp":0x39
+        },
         "sp":{ "r8":0xE9 },
         "d8":0xC6
     },
@@ -500,12 +518,15 @@ SOME_ARGS["ld"]["e"]["d8"] = 0x1E
 SOME_ARGS["ld"]["l"]["d8"] = 0x2E
 SOME_ARGS["ld"]["a"]["d8"] = 0x3E
 
-def locateOperand(op, ptr, allow=(8,16)):
-    for p in "adri":
+def locateOperand(op, ptr, allow=(8,16,'r')):
+    prefix_opts = "adi"
+    if 'r' in allow:
+        prefix_opts += 'r'
+    for p in prefix_opts:
         opts = []
         if 16 in allow:
             opts.append(("16", Block.pushShort))
-        if 8 in allow:
+        if 8 in allow or p == 'r':
             opts.append(("8", Block.pushByte))
         for t in opts:
             s, func = t
@@ -516,6 +537,7 @@ def locateOperand(op, ptr, allow=(8,16)):
                 o = "(" + o + ")"
                 if o in op:
                     return (o, func)
+
     print("Error in " + str(op))
     return (None, None)
 
@@ -538,14 +560,14 @@ def writeOpcode(mnemonic, block, ops, i, operands):
             num = block.eval(operand[1:-1])
             # print("INFO: Evaluated " + operand[1:-1] + " as " + hex(num))
         else:
-            if operand[0] in "<>=":
+            if operand[0] in "<>=@":
                 c = operand[0]
                 operand = operand[1:]
                 operand = c + block.equ.get(operand, operand)
             else:
                 operand = block.equ.get(operand, operand)
             try:
-                if operand[0] in "<>=":
+                if operand[0] in "<>=@":
                     c = operand[0]
                     num = int(operand[1:], 0)
                     if c == '>':
@@ -571,11 +593,14 @@ def writeOpcode(mnemonic, block, ops, i, operands):
             elif operand[0] == '<':
                 pushReloc = Block.pushReloc8l
                 allow = [8]
+            elif operand[0] == '@':
+                pushReloc = Block.pushRelocRel
+                allow = ['r']
             else:
                 pushReloc = Block.pushReloc16
                 allow = [16]
             
-            if operand[0] in "=<>":
+            if operand[0] in "=<>@":
                 operand = operand[1:]
             
             key, func = locateOperand(ops, ptr, allow)