Implement 'with interrupts off'.

src/sixtypical/analyzer.py

@@ -232,5 +232,7 @@ def analyze_instr(instr, context, routines):
         context.set_written(dest)
         context.set_touched(REG_A, FLAG_Z, FLAG_N)
         context.set_unmeaningful(REG_A, FLAG_Z, FLAG_N)
+    elif opcode == 'with-sei':
+        analyze_block(instr.block, context, routines)
     else:
         raise NotImplementedError(opcode)

src/sixtypical/compiler.py

@@ -16,6 +16,7 @@ from sixtypical.gen6502 import (
     CMP, CPX, CPY, AND, ORA, EOR,
     BCC, BCS, BNE, BEQ,
     JMP, JSR, RTS,
+    SEI, CLI,
 )
 
 
@@ -236,5 +237,9 @@ class Compiler(object):
                 if cls is None:
                     raise UnsupportedOpcodeError(instr)
                 self.emitter.emit(cls(Relative(top_label)))
+        elif opcode == 'with-sei':
+            self.emitter.emit(SEI())
+            self.compile_block(instr.block)
+            self.emitter.emit(CLI())
         else:
             raise NotImplementedError

src/sixtypical/evaluator.py

@@ -160,5 +160,7 @@ def eval_instr(instr, context, routines):
         context.set(REG_A, 0)
         context.set(FLAG_Z, 0)
         context.set(FLAG_N, 0)
+    elif opcode == 'with-sei':
+        eval_block(instr.block)
     else:
         raise NotImplementedError

src/sixtypical/gen6502.py

@@ -135,6 +135,12 @@ class CLC(Opcode):
     }
 
 
+class CLI(Opcode):
+    opcodes = {
+        Implied:   0x58,
+    }
+
+
 class CMP(Opcode):
     opcodes = {
         Immediate: 0xc9,
@@ -287,6 +293,12 @@ class SEC(Opcode):
     }
 
 
+class SEI(Opcode):
+    opcodes = {
+        Implied:   0x78,
+    }
+
+
 class STA(Opcode):
     opcodes = {
         Absolute:  0x8d,

src/sixtypical/parser.py

@@ -257,5 +257,10 @@ class Parser(object):
             self.scanner.expect(',')
             dest = self.locexpr()
             return Instr(opcode=opcode, dest=dest, src=src)
+        elif self.scanner.consume("with"):
+            self.scanner.expect("interrupts")
+            self.scanner.expect("off")
+            block = self.block()
+            return Instr(opcode='with-sei', dest=None, src=None, block=block)
         else:
             raise ValueError('bad opcode "%s"' % self.scanner.token)

tests/SixtyPical Syntax.md

@@ -205,6 +205,8 @@ Declaring a vector.
     |     ld a, 0
     | }
     | routine main {
-    |     copy foo, cinv
+    |     with interrupts off {
+    |         copy foo, cinv
+    |     }
     | }
     = ok