core: refactor how launch() works in preperation for libc integration

riscemu/MMU.py

@@ -72,7 +72,7 @@ class MMU:
                 return sec
         return None
 
-    def get_bin_containing(self, addr: T_AbsoluteAddress) -> Optional[Program]:
+    def get_program_at_addr(self, addr: T_AbsoluteAddress) -> Optional[Program]:
         for program in self.programs:
             if program.base <= addr < program.base + program.size:
                 return program
@@ -192,7 +192,7 @@ class MMU:
         if not sec:
             return "unknown at 0x{:0x}".format(address)
 
-        bin = self.get_bin_containing(address)
+        bin = self.get_program_at_addr(address)
         secs = set(sec.name for sec in bin.sections) if bin else []
         elf_markers = {
             "__global_pointer$",
@@ -347,3 +347,13 @@ class MMU:
             return sec.context
 
         return InstructionContext()
+
+    def find_entrypoint(self) -> int | None:
+        # try to find the global entrypoint
+        if "_start" in self.global_symbols:
+            return self.global_symbols["_start"]
+        # otherwise find a main (that's not necessarily global)
+        for p in self.programs:
+            if "main" in p.context.labels:
+                return p.context.resolve_label("main")
+        return None

riscemu/__main__.py

@@ -176,7 +176,7 @@ unlimited_regs:       Allow an unlimited number of registers""",
         cpu.setup_stack(cfg.stack_size)
 
         # launch the last loaded program
-        cpu.launch(cpu.mmu.programs[-1], verbose=cfg.verbosity > 1)
+        cpu.launch(verbose=cfg.verbosity > 1)
         sys.exit(cpu.exit_code if not args.ignore_exit_code else 0)
 
     except RiscemuBaseException as e:

riscemu/interactive.py

@@ -31,6 +31,6 @@ if __name__ == "__main__":
 
     cpu.setup_stack()
 
-    cpu.launch(program)
+    cpu.launch()
 
     sys.exit(cpu.exit_code)

riscemu/types/cpu.py

@@ -1,13 +1,12 @@
-import typing
 from abc import ABC, abstractmethod
-from typing import List, Type, Callable, Set, Dict, TYPE_CHECKING
+from typing import List, Type, Callable, Set, Dict, TYPE_CHECKING, Iterable
 
 from ..registers import Registers
 from ..config import RunConfig
-from ..colors import FMT_RED, FMT_NONE, FMT_ERROR, FMT_CPU
+from ..colors import FMT_NONE, FMT_CPU
 from . import T_AbsoluteAddress, Instruction, Program, ProgramLoader
 
-if typing.TYPE_CHECKING:
+if TYPE_CHECKING:
     from ..MMU import MMU
     from ..instructions import InstructionSet
 
@@ -91,27 +90,26 @@ class CPU(ABC):
     def run(self, verbose: bool = False):
         pass
 
-    def launch(self, program: Program, verbose: bool = False):
-        if program not in self.mmu.programs:
-            print(
-                FMT_ERROR + "[CPU] Cannot launch program that's not loaded!" + FMT_NONE
-            )
-            return
+    def launch(self, verbose: bool = False):
+        entrypoint = self.mmu.find_entrypoint()
+
+        if entrypoint is None:
+            entrypoint = self.mmu.programs[0].entrypoint
+
         if self.conf.verbosity > 0:
             print(
                 FMT_CPU
                 + "[CPU] Started running from {}".format(
-                    self.mmu.translate_address(program.entrypoint)
+                    self.mmu.translate_address(entrypoint)
                 )
                 + FMT_NONE
             )
-            print(program)
-        self.pc = program.entrypoint
+        self.pc = entrypoint
         self.run(verbose)
 
     @classmethod
     @abstractmethod
-    def get_loaders(cls) -> typing.Iterable[Type[ProgramLoader]]:
+    def get_loaders(cls) -> Iterable[Type[ProgramLoader]]:
         pass
 
     def get_best_loader_for(self, file_name: str) -> Type[ProgramLoader]: