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bf: extract loop_end to its own function

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This commit is contained in:
Aryadev Chavali
2026-03-17 21:28:40 +00:00
parent c6433b4429
commit 071fe2ff98
1 changed files with 22 additions and 22 deletions
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44
src/bf.c
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@@ -27,10 +27,9 @@ struct MachineContext
u64 total_iters;
};
// This function implements the jump-forward operator of BrainFuck `[`, given
// the current state of the machine. We maintain a `loop_stack` which allows us
// to trivially implement the jump-back operator `]` - essentially heavy forward
// investment.
// Jump-forward operator of BrainFuck `[`. We maintain a `loop_stack` which
// allows us to trivially implement the jump-back operator `]` - essentially
// heavy forward investment.
void loop_begin(struct ProgramConcat *prg, struct MachineContext *ctx,
vec_t *loop_stack)
{
@@ -75,6 +74,24 @@ void loop_begin(struct ProgramConcat *prg, struct MachineContext *ctx,
}
}
void loop_end(struct ProgramConcat *prg, struct MachineContext *ctx,
vec_t *loop_stack)
{
if (!prg->tape[ctx->head0])
{
++ctx->ip;
}
else if (loop_stack->size < sizeof(u64))
{
// NOTE: as per paper, terminate.
ctx->ip = sizeof(prg->tape);
}
else
{
ctx->ip = *(u64 *)vec_pop(loop_stack, sizeof(ctx->ip));
}
}
void program_execute(struct ProgramConcat *prg)
{
vec_t loop_stack = {0};
@@ -120,28 +137,11 @@ void program_execute(struct ProgramConcat *prg)
++ctx.ip;
break;
case '[':
{
loop_begin(prg, &ctx, &loop_stack);
break;
}
case ']':
{
if (!prg->tape[ctx.head0])
{
++ctx.ip;
continue;
}
else if (loop_stack.size < sizeof(u64))
{
// NOTE: as per paper, terminate.
ctx.ip = sizeof(prg->tape);
}
else
{
ctx.ip = *(u64 *)vec_pop(&loop_stack, sizeof(ctx.ip));
}
loop_end(prg, &ctx, &loop_stack);
break;
}
default:
++ctx.ip;
break;