- (FrameClass::FixFix, _) => chan.num_env / 2 - 1,
- (FrameClass::VarFix, 0) => 0,
- (FrameClass::VarFix, 1) => chan.num_env - 2,
- (FrameClass::VarFix, _) => chan.pointer as usize - 2,
- (_, 0) | (_, 1) => chan.num_env - 2,
- (_, _) => chan.num_env - (chan.pointer as usize),
+ (FrameClass::FixFix, _) => chan.num_env / 2,
+ (FrameClass::VarFix, 0) => 1,
+ (FrameClass::VarFix, 1) => chan.num_env - 1,
+ (FrameClass::VarFix, _) => chan.pointer as usize - 1,
+ (_, 0) | (_, 1) => chan.num_env - 1,
+ (_, _) => chan.num_env + 1 - (chan.pointer as usize),