/* test_host_rom_pack.c -- the ROM's slot packer, word for word with asm.c.
 *
 * Plan Task 5.  (OP) ( op -- ), (LIT) ( v -- ), (BRANCH) ( op target -- ),
 * (BRANCH>) ( op -- ref ), (RESOLVE) ( ref target -- ) and (LABEL)
 * ( -- addr ) lay code down exactly as v4/src/asm.c does, with text.c's
 * branch placement: a branch goes in a slot only if that slot reaches the
 * whole address space.  Random sequences are applied both ways -- asm.c on
 * node A, the ROM on node B -- and memory is compared word for word; a
 * sequence that is an error on one side must be an error on the other.
 */
#include "rom_harness.h"

static int failures = 0, checks = 0;
#define CHECK(c,...) do{checks++; if(!(c)){failures++; printf("FAIL %s:%d: ",__FILE__,__LINE__); printf(__VA_ARGS__); printf("\n");}}while(0)

static v4_node a, b;
static v4_asm  as;

static unsigned long long seed = 20261015u;
static unsigned rnd(unsigned n) { seed = seed * 6364136223846793005ull + 1442695040888963407ull; return (unsigned)((seed >> 33) % n); }

/* text.c's place_branch, for the asm.c side */
static void place_branch(void)
{
    if (as.slot == 0) return;
    if (!v4_iword_branch_legal(as.slot) || (v4_ucell)v4_iword_slot_mask(as.slot) < (v4_ucell)ROM_ADDR_TOP)
        (void)v4_asm_label(&as);
}

/* call a ROM routine with up to two arguments; 1 if it returned */
static int rom(const char *name, int argc, v4_cell x, v4_cell y)
{
    if (argc > 0) v4_dstack_push(&b.ds, x);
    if (argc > 1) v4_dstack_push(&b.ds, y);
    if (rom_call(&b, name, 1000000)) return 1;
    printf("    %s did not return: P %ld, stopped %d, fault kind %u at %ld\n", name, (long)b.p, b.stopped, b.fault_kind, (long)b.fault_addr);
    return 0;
}

static int rom_failed(void) { return b.mem[ROM_FAILED] != 0; }

static const unsigned branch_ops[5] = { V4_OP_JUMP, V4_OP_CALL, V4_OP_NEXT, V4_OP_IF, V4_OP_MINUS_IF };

/* one random sequence from `origin`; 1 if both sides agree throughout */
static int trial(v4_cell origin, unsigned steps)
{
    v4_asm_ref aref[64];
    v4_cell    bref[64], labels[64], ha, hb, w;
    unsigned   nref = 0, nlab = 0, i, k;

    v4_node_reset(&a);
    v4_asm_begin(&as, &a, origin);
    rom_boot(&b);
    v4_node_console_input_attach(&b, -1, -1);      /* the packer reads no input: near the top of RAM, those are words */
    b.mem[ROM_HERE] = origin;

    for (i = 0; i < steps; i++) {
        unsigned what = rnd(100);
        int ea, eb;
        if (what < 45) {                                   /* an ordinary opcode */
            unsigned op;
            do op = rnd(32); while (v4_op_is_branch(op) || op == V4_OP_FETCH_P);
            v4_asm_op(&as, op);
            if (!rom("(OP)", 1, (v4_cell)op, 0)) return 0;
        } else if (what < 70) {                            /* a literal */
            v4_cell v = (v4_cell)rnd(2000) - 1000;
            if (rnd(4) == 0) v = (v4_cell)((v4_ucell)0 - (v4_ucell)rnd(5)) ;
            v4_asm_lit(&as, v);
            if (!rom("(LIT)", 1, v, 0)) return 0;
        } else if (what < 80) {                            /* a branch back, or anywhere */
            unsigned op = branch_ops[rnd(5)];
            v4_cell t = nlab && rnd(3) ? labels[rnd(nlab)] : (v4_cell)rnd((unsigned)ROM_ADDR_TOP + 1u);
            if (rnd(40) == 0) t = 200000;                  /* out of reach of any slot but 0 */
            place_branch();
            v4_asm_branch(&as, op, t);
            if (!rom("(BRANCH)", 2, (v4_cell)op, t)) return 0;
        } else if (what < 90 && nref < 64) {               /* a branch forward */
            unsigned op = branch_ops[rnd(5)];
            place_branch();
            aref[nref] = v4_asm_branch_fwd(&as, op);
            if (!rom("(BRANCH>)", 1, (v4_cell)op, 0)) return 0;
            bref[nref] = v4_dstack_pop(&b.ds);
            nref++;
        } else if (nlab < 64) {                            /* a label, and some forward branches resolved to it */
            v4_cell la = v4_asm_label(&as), lb;
            if (!rom("(LABEL)", 0, 0, 0)) return 0;
            lb = v4_dstack_pop(&b.ds);
            if (la != lb) { printf("    label: asm %ld, ROM %ld\n", (long)la, (long)lb); return 0; }
            labels[nlab++] = la;
            for (k = 0; k < nref; ) {
                if (rnd(2)) { k++; continue; }
                v4_asm_resolve(&as, aref[k], la);
                if (!rom("(RESOLVE)", 2, bref[k], la)) return 0;
                aref[k] = aref[nref - 1]; bref[k] = bref[nref - 1]; nref--;
            }
        }
        ea = as.error != 0;
        eb = rom_failed();
        if (ea != eb) { printf("    step %u: asm error %d, ROM error %d (code %ld)\n", i, ea, eb, (long)b.mem[ROM_FAILED]); return 0; }
        if (ea) return 1;                                  /* both refused: the sequence ends there */
        if (b.ds.depth != 0) { printf("    step %u: the ROM left %u on the stack\n", i, b.ds.depth); return 0; }
    }
    ha = v4_asm_label(&as);
    if (!rom("(LABEL)", 0, 0, 0)) return 0;
    hb = v4_dstack_pop(&b.ds);
    if (as.error || rom_failed()) return (as.error != 0) == rom_failed();
    if (ha != hb) { printf("    end: asm here %ld, ROM %ld\n", (long)ha, (long)hb); return 0; }
    for (w = origin; w < ha; w++)
        if (a.mem[w] != b.mem[w]) { printf("    word %ld: asm %lx, ROM %lx\n", (long)w, (unsigned long)a.mem[w], (unsigned long)b.mem[w]); return 0; }
    return 1;
}

int main(void)
{
    unsigned t, good = 0;
    for (t = 0; t < 400; t++) if (trial(16, 120 + rnd(200))) good++; else { CHECK(0, "trial %u disagrees", t); break; }
    CHECK(good == 400, "400 random sequences agree word for word: %u", good);

    /* memory runs out: a sequence that starts near the top of RAM */
    CHECK(trial((v4_cell)V4_NODE_WORDS - 20, 200), "memory full is an error on both sides");

    /* a forward branch that cannot reach (Review Focus 2) */
    {
        v4_asm_ref ar; v4_cell br;
        v4_node_reset(&a); v4_asm_begin(&as, &a, 16);
        rom_boot(&b); b.mem[ROM_HERE] = 16;
        v4_asm_op(&as, V4_OP_DUP); v4_asm_op(&as, V4_OP_DUP);
        rom("(OP)", 1, V4_OP_DUP, 0); rom("(OP)", 1, V4_OP_DUP, 0);
        place_branch();
        ar = v4_asm_branch_fwd(&as, V4_OP_JUMP);
        rom("(BRANCH>)", 1, V4_OP_JUMP, 0); br = v4_dstack_pop(&b.ds);
        v4_asm_resolve(&as, ar, 400000);
        rom("(RESOLVE)", 2, br, 400000);
        CHECK(as.error && b.mem[ROM_FAILED] == ROM_ERR_FIT, "out of reach: refused by both, ROM code %ld", (long)b.mem[ROM_FAILED]);
    }

    /* a ref to a word with no branch in it is refused, not looped on */
    rom_boot(&b); b.mem[ROM_HERE] = 16;
    rom("(OP)", 1, V4_OP_DUP, 0);
    rom("(LABEL)", 0, 0, 0); (void)v4_dstack_pop(&b.ds);
    CHECK(rom("(RESOLVE)", 2, 16, 40) && b.mem[ROM_FAILED] == ROM_ERR_FIT, "no branch at the ref: does not fit, code %ld", (long)b.mem[ROM_FAILED]);

    /* opcodes the packer does not take as ordinary ones */
    rom_boot(&b); b.mem[ROM_HERE] = 16;
    rom("(OP)", 1, V4_OP_FETCH_P, 0);
    CHECK(b.mem[ROM_FAILED] == ROM_ERR_OPCODE, "@p is written as a literal, not an opcode");
    rom_boot(&b); b.mem[ROM_HERE] = 16;
    rom("(OP)", 1, V4_OP_CALL, 0);
    CHECK(b.mem[ROM_FAILED] == ROM_ERR_OPCODE, "a branch is not an ordinary opcode");
    rom_boot(&b); b.mem[ROM_HERE] = 16;
    rom("(OP)", 1, 32, 0);
    CHECK(b.mem[ROM_FAILED] == ROM_ERR_OPCODE, "32 is not an opcode");

    printf("test_host_rom_pack: %d checks, %d failures\n", checks, failures);
    return failures != 0;
}