c/tty/tty_legacy.c · 6808 字节 · 下载原文

// 老 TTY 程序**依赖的终端行为**体检 —— 命令行页能不能跑它们，看这个。

// Health check for the **terminal behaviors old TTY programs depend on** — this tells you whether the command-line page can run them.

//

// 为什么单写一个探针而不是拿真程序试：真程序（`sl`/`cmatrix`/`htop` 那类）几乎都依赖

// Why write a probe instead of trying real programs: real programs (the `sl`/`cmatrix`/`htop` kind) almost all depend on

// **ncurses**，没有它连编都编不过；而 ncurses 底下真正依赖的终端行为其实就这么几条。

// **ncurses**, and without it they do not even compile; yet the terminal behaviors they really rely on under ncurses are just these few.

// 先把这几条量清楚，"哪些老程序能跑"才有答案，而不是一个个试运气。

// Getting these few measured clearly first is what makes "which old programs can run" answerable, instead of trying your luck one by one.

//

// 每一条都先打一行带标签的说明，再打实际的序列 —— 看屏幕就知道哪条成立。

// Each item first prints a labeled description line, then the actual sequence — one look at the screen tells you which one holds.

//

// 跑法：命令行页输入  vml run examples/c/tty_legacy.c

// How to run: type this on the command-line page  vml run examples/c/tty_legacy.c


#include <vml_ui.h>

int main()
{
    int i;
    int lang = ui_scr_get_language();   /* 界面语言：开局查一次（ui_scr_get_language 是 syscall，别每帧调） */
                                    /* UI language: queried once at start (ui_scr_get_language is a syscall, do not call it every frame) */

    // ── ① 回车覆写（`\r`）：**进度条就靠它** ──

    // ── ① Carriage-return overwrite (`\r`): **progress bars rely on it** ──

    // 真终端里 `\r` 把光标移回行首，后面的输出盖掉同一行 ⇒ 屏幕上只有一行在变。

    // On a real terminal `\r` moves the cursor back to the start of the line, and later output overwrites that same line ⇒ only one line changes on screen.

    // 若实现只是把 `\r` 丢掉或当换行，这里会看到多行（或一行挤在一起）。

    // If the implementation merely drops `\r` or treats it as a newline, you will see several lines here (or one crammed line).

    puts("[1] CR-overwrite (progress bar) ->");
    for (i = 1; i <= 5; i++) {
        printf("\r    progress [%d/5]", i);
    }
    puts("");

    // ── ② 制表符（`\t`）：**表格对齐**靠它 ──

    // ── ② Tab character (`\t`): **table alignment** relies on it ──

    // 真终端按 8 列制表位（或可配）跳到下一个制表位。若被当普通空格，

    // A real terminal jumps to the next tab stop at 8 columns (or a configurable width). If it is treated as an ordinary space,

    // 下面的列就不会对齐（`ls`/`df`/`ps` 的表格都会歪）。

    // the columns below will not line up (the tables from `ls`/`df`/`ps` all go crooked).

    puts("[2] TAB columns (should align) ->");
    puts("a\tb\tc");
    puts("aaaa\tbbbb\tcccc");
    puts("aa\tbb\tcc");

    // ── ③ 退格叠打（`\b`）：**粗体/下划线**靠它 ──

    // ── ③ Backspace overstrike (`\b`): **bold/underline** relies on it ──

    // 老手册页的粗体就是 `X\bX`（打两遍，中间退一格）—— 真终端叠出不加粗，

    // Bold in old man pages is just `X\bX` (print twice with a backspace in between) — a real terminal overstrikes without bolding,

    // 但至少**不该把 `\b` 显示成可见字符**。

    // but at the very least **it must not display `\b` as a visible character**.

    puts("[3] backspace overstrike ->");
    puts(lang == 0 ? "A\bB\bC    <- 期望看到 ABC，且没有可见的退格符"
                   : "A\bB\bC    <- expect to see ABC, with no visible backspace");


    // ── ④ 光标定位与清屏（CSI 序列）：**全屏程序**靠它 ──

    // ── ④ Cursor positioning and screen clearing (CSI sequences): **full-screen programs** rely on it ──

    // 我们的命令行页会**吃掉**这类序列（不落到正文），所以下面应当只看到两行文字，

    // Our command-line page **eats** such sequences (they do not reach the text body), so below you should see only two lines of text,

    // 没有 `[2J`/`[H` 这种字面量漏出来。

    // with no literals like `[2J`/`[H` leaking through.

    puts("[4] cursor/clear sequences (should be eaten, not shown) ->");
    printf("\x1b[2J\x1b[H    after clear+home\n");
    printf("\x1b[31m    red line via SGR\x1b[0m\n");

    // ── ⑤ 亮色 / 256 色 / 真彩 ──

    // ── ⑤ Bright / 256-color / truecolor ──

    // 三档都在这里：16 色亮色不带分号，256 色（`38;5;N`）与真彩（`38;2;r;g;b`）**必须带分号**。

    // All three tiers are here: the 16 bright colors carry no semicolon, while 256-color (`38;5;N`) and truecolor (`38;2;r;g;b`) **must carry semicolons**.

    // ~~后者此前被一个汇编器缺陷吃掉（`.string` 里的 `;` 被当行内注释截断 ⇒ 转义残废、颜色静默不对），修好之前这一节只能测 16 色。~~

    // ~~The latter was previously eaten by an assembler defect (a `;` inside `.string` was treated as an inline comment and truncated ⇒ escapes crippled,

    // and colors silently wrong), so before the fix this section could only test 16 colors.~~

    // ✅ **已修好（2026-10-04 复验）**：实测含分号的字符串 `"A;5;B"` 原样打出 `A;5;B` —— `.string` 里的 `;` 不再被截断。

    // ✅ **fixed (re-checked 2026-10-04)**: the string `"A;5;B"` measured printing back as `A;5;B` — a `;` inside `.string` is no longer truncated.

    // 见 `scripts/vml-c-probe/cases/10-semi-in-string.c`（那条探针的历史现场）。

    // See `scripts/vml-c-probe/cases/10-semi-in-string.c` (the historical site of that probe).

    puts("[5] colors: bright / 256-color / truecolor ->");
    printf("\x1b[91m    bright red\x1b[0m\n");
    printf("\x1b[104m    bright blue background\x1b[0m\n");
    printf("\x1b[38;5;208m    256-color orange (38;5;208)\x1b[0m\n");
    printf("\x1b[38;2;255;105;180m    truecolor hot pink (38;2;255;105;180)\x1b[0m\n");
    printf("\x1b[48;5;24m    256-color background\x1b[0m\n");

    // ── ⑥ 宽字符（CJK）—— 列宽必须按 2 格算 ──

    // ── ⑥ Wide characters (CJK) — column width must count as 2 cells ──

    puts("[6] wide chars (CJK = 2 cells) ->");
    puts(lang == 0 ? "    中文宽字符|ascii|中文" : "    wide: 中文宽字符|ascii|中文");
    return 0;
}