LithosAnanke/kernel/src/v4/sk_v4.c

/* sk_v4.c -- StarForth v4 on bare metal: one host node at a prompt.
 *
 * The node is the golden model of the F18-derived engine (v4/src).  It comes
 * up as the hosted v4 system does, by v4_boot_run (v4/include/v4/boot.h):
 * the machine's ROM assembles the system from its source, then the capsules
 * from the directory baked into this kernel are loaded, each checked and its
 * parity line printed, then the prompt.
 * docs/v4.0.0/NUCLEUS.md.  This file is all the kernel adds:
 *
 *   - what the node prints goes to the kernel's console;
 *   - the prompt, and the line: it is read and edited here and handed to the
 *     node whole (docs/v4.0.0/ENGINE.md 3.1), and how it ended is said here;
 *   - blocks are kept in memory, and are gone at power-off.
 *
 * This is the lone node, started before the kernel's fleet and beside it.
 * It goes when the node is brought up in the VM's place (ENGINE.md step 4).
 *
 * Nothing of the v3 VM is started.  docs/v4.0.0/DECOMPOSITION.md.
 */
#include "starkernel/v4/sk_v4.h"
#include "starkernel/console.h"
#include "starkernel/arch.h"
#include "v4/boot.h"
#include "block_subsystem.h"

#define SK_V4_LINE   255u                /* what the line editor here takes */

static v4_node       sk_v4_node;
static v4_exec_state sk_v4_es;
static v4_heat       sk_v4_heat;
static v4_image      sk_v4_image;

static char          sk_v4_text[SK_V4_LINE + 1u];

/* POST's block RAM, as the v3 path has (sk_vm_bootstrap.c, sk_post_blk_ram):
 * the node boots and is POSTed with these blocks, 1 to 2047 and nothing
 * above them, and the kernel's real chain is set up afterwards. */
static uint8_t       sk_v4_post_blk_ram[BLK_RAM_BLOCKS * BLK_FORTH_SIZE];

static void sk_v4_out(const char *text, unsigned len)
{
    unsigned i;
    for (i = 0; i < len; i++) console_putc(text[i]);
}

/* a character for a line that reads the keyboard, when there is one */
static int sk_v4_key(void)
{
    int c = console_getc();
    return c < 0 ? V4_BOOT_KEY_NONE : c;
}

/* THE KERNEL'S WORDS for the lone node.  BYE is v3's (mama_word_bye): a cold
 * restart.  v3's reaps Hera's children first; the lone node is started
 * before there is a fleet, so there are none.  The rest of the kernel's
 * words come when the node is brought up in the VM's place (ENGINE.md
 * step 4), where v3's own functions serve them. */
static const char *const sk_v4_words[] = { "BYE" };

static void sk_v4_serve(v4_node *node, unsigned request)
{
    (void)node;
    if (request == 1) {
        console_println("BYE: cold restart");
        arch_cold_reset();
    }
}

/* Read a line from the keyboard: characters are echoed, backspace rubs one
 * out, Enter ends it.  Returns its length. */
static unsigned sk_v4_readline(void)
{
    unsigned len = 0;
    for (;;) {
        int c = console_getc();
        if (c < 0) continue;
        if (c == '\r' || c == '\n') { console_putc('\n'); return len; }
        if (c == 8 || c == 127) {
            if (len > 0) { len--; console_putc(8); console_putc(' '); console_putc(8); }
        } else if (c >= 32 && c < 127 && len < SK_V4_LINE) {
            sk_v4_text[len++] = (char)c;
            console_putc((char)c);
        }
    }
}

void sk_v4_run(void (*chain)(void))
{
    v4_boot boot;

    console_println("StarForth v4: one host node, the F18-derived engine");
    sk_v4_image = v4_map_image;
    boot.n = &sk_v4_node; boot.es = &sk_v4_es; boot.h = &sk_v4_heat; boot.im = &sk_v4_image;
    boot.out = sk_v4_out; boot.key = sk_v4_key;
    boot.words = sk_v4_words; boot.word_count = sizeof sk_v4_words / sizeof sk_v4_words[0]; boot.serve = sk_v4_serve;
    blk_subsys_init(sk_v4_post_blk_ram, sizeof(sk_v4_post_blk_ram));
    if (!v4_boot_run(&boot)) {
        console_println("StarForth v4: not started");
        for (;;) { }
    }
    if (chain) {
        /* the blocks are other blocks now: what the node has in its two
         * buffers is POST's, and is let go */
        chain();
        if (v4_boot_line(&boot, "EMPTY-BUFFERS", 13) != V4_TEXT_COMPLETED) {
            console_println("StarForth v4: the node did not let go of POST's blocks");
            for (;;) { }
        }
    }

    /* The prompt is the host's: read a line, hand it to the node, say how it
     * ended. */
    for (;;) {
        unsigned len;
        int how;

        console_puts("ok> ");
        len = sk_v4_readline();
        how = v4_boot_line(&boot, sk_v4_text, len);
        /* The line is waiting for an answer no one here can send.  The next
         * line typed breaks the wait: the line that was waiting ends in an
         * error, and then the line just typed is done (v4/boot.h). */
        while (how == V4_BOOT_LINE_WAITING) {
            len = sk_v4_readline();
            how = v4_boot_line(&boot, sk_v4_text, len);
            if (how == V4_TEXT_ERROR) console_puts(" ERROR\nok> ");
            else if (how == V4_TEXT_COMPLETED) console_puts(" ok\nok> ");
            else break;
            how = v4_boot_line(&boot, 0, 0);
        }
        if (how == V4_TEXT_COMPLETED) console_puts(" ok\n");
        else if (how == V4_TEXT_ERROR) console_puts(" ERROR\n");
        else if (how == V4_BOOT_LINE_REFUSED) console_puts("Message refused\n ERROR\n");      /* the node's wire is full: error 19's words */
        else if (how == V4_BOOT_LINE_STOPPED) {
            console_println("StarForth v4: the node stopped on a fault");
            for (;;) { }
        }
    }
}