A controller instruction in our register-machine language has one of the
following forms, where each ⟨
我们的寄存器机器语言中，控制器指令具有以下形式之一，其中每个 ⟨
i
n
p
u
t
i
⟩ is either
(reg ⟨register-name⟩) or (const ⟨constant-value⟩).
These instructions were introduced in 5.1.1:
⟩ 是 (reg ⟨register-name⟩) 或 (const ⟨constant-value⟩) 之一。以下指令在 5.1.1 节中已作介绍：
The use of registers to hold labels was introduced in 5.1.3:
用寄存器保存标号的用法在 5.1.3 节中已作介绍：
Instructions to use the stack were introduced in 5.1.4:
使用栈的指令在 5.1.4 节中已作介绍：
The only kind of ⟨constant-value⟩ we have seen so far is a number,
but later we will use strings, symbols, and lists.
For example,
目前为止我们见到的 ⟨constant-value⟩ 只有数，但后续还将用到字符串、符号和表。例如：
(const "abc") is the string "abc",
(const "abc") 是字符串 "abc"，
(const abc) is the symbol abc,
(const abc) 是符号 abc，
(const (a b c)) is the list (a b c),
(const (a b c)) 是表 (a b c)，
and (const ()) is the empty list.
(const ()) 是空表。
(assign ⟨register-name⟩ (reg ⟨register-name⟩))
(assign ⟨register-name⟩
(const ⟨constant-value⟩))
(assign ⟨register-name⟩
(op ⟨operation-name⟩)
⟨input₁⟩ … ⟨inputₙ⟩)
(perform (op ⟨operation-name⟩)
⟨input₁⟩
…
⟨inputₙ⟩)
(test (op ⟨operation-name⟩)
⟨input₁⟩
…
⟨inputₙ⟩)
(branch (label ⟨label-name⟩))
(goto (label ⟨label-name⟩))(assign ⟨register-name⟩ (label ⟨label-name⟩))
(goto (reg ⟨register-name⟩))(save ⟨register-name⟩)
(restore ⟨register-name⟩)