#include "gbos.h"
/* xxd [-c N] [file]: hex dump a file, or stdin.
 *
 * Eight bytes per line, not the usual sixteen: offset + 8 hex pairs + the
 * ASCII column is 38 of the terminal's 40 columns, where 16 would wrap every
 * line and make the dump unreadable. -c overrides it anyway.
 *
 * There is no seek syscall, so this streams from the start - which is also
 * why there is no -s (skip). -l stops after N bytes, which is how you look at
 * a program image: /bin/<prog> is a whole 16 KiB ROM bank, and dumping all of
 * it is 2048 lines (and more than a pipe's temp file can hold). */

#define MAXC 16

/* atou() is 8-bit; -l wants up to 16 KiB */
static unsigned int atou16(const char *s) {
    unsigned int n = 0;
    while (*s >= '0' && *s <= '9') {
        n = n * 10 + (unsigned char)(*s - '0');
        s++;
    }
    return n;
}

static char hexd(unsigned char v) { return (char)(v < 10 ? '0' + v : 'a' + (v - 10)); }
static void hex2(unsigned char v) {
    putc(hexd((unsigned char)(v >> 4)));
    putc(hexd((unsigned char)(v & 15)));
}
static void hex4(unsigned int v) {
    hex2((unsigned char)(v >> 8));
    hex2((unsigned char)v);
}

void main(void) {
    char *argv[8];
    unsigned char buf[MAXC];
    unsigned char argc = argv_parse(argv, 8);
    char *cv = optval(argv, argc, 'c');
    char *lv = optval(argv, argc, 'l');
    unsigned int limit = 0; /* 0 = no limit */
    unsigned char cols = 8, fd = NOFD, n = 0, i;
    unsigned int off = 0;
    char *fname = 0;
    int ch;

    if (cv) {
        cols = atou(cv);
        if (cols == 0 || cols > MAXC) cols = 8;
    }
    if (lv) limit = atou16(lv);
    for (i = 0; i < argc; i++) {
        if (argv[i][0] == '-') continue;
        if (cv == argv[i] || lv == argv[i]) continue;
        fname = argv[i];
        break;
    }
    if (fname) {
        fd = open(fname, O_READ);
        if (fd == EISDIR) {
            puts("xxd: is a directory");
            nl();
            sexit(2);
        }
        if (fd == NOFD) {
            puts("xxd: no such file");
            nl();
            sexit(2);
        }
    }

    for (;;) {
        if (limit && off + n >= limit) ch = -1; /* -l: stop after N bytes */
        else if (fd == NOFD) {
            char c = readc();
            ch = (c == EOF) ? -1 : c;
        } else ch = fgetc(fd);
        if (ch >= 0) buf[n++] = (unsigned char)ch;
        if (n == cols || (ch < 0 && n)) { /* full line, or the last one */
            hex4(off);
            puts(": ");
            for (i = 0; i < cols; i++) {
                if (i < n) hex2(buf[i]);
                else {
                    putc(' ');
                    putc(' ');
                } /* pad so ASCII stays aligned */
                putc(' ');
            }
            for (i = 0; i < n; i++) putc((buf[i] >= 32 && buf[i] < 127) ? (char)buf[i] : '.');
            nl();
            off += n;
            n = 0;
        }
        if (ch < 0) break;
    }
    if (fd != NOFD) close(fd);
}