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collapseos/cvm/vm.c
Virgil Dupras 80d1b59050 Add words |M and |L
Splitting a word into MSB/LSB pairs happens often and is worth, I
think, native words. Also, I'm going to need it in the upcoming
commits.
2020-12-07 20:11:49 -05:00

455 lines
11 KiB
C

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "vm.h"
// Port for block reads. Each read or write has to be done in 5 IO writes:
// 1 - r/w. 1 for read, 2 for write.
// 2 - blkid MSB
// 3 - blkid LSB
// 4 - dest addr MSB
// 5 - dest addr LSB
#define BLK_PORT 0x03
static VM vm;
static uint64_t blkop = 0; // 5 bytes
static FILE *blkfp;
// Read single byte from I/O handler, if set. addr is a word only because of
// Forth's cell size, but can't actually address more than a byte-ful of ports.
static byte io_read(word addr)
{
addr &= 0xff;
IORD fn = vm.iord[addr];
if (fn != NULL) {
return fn();
} else {
fprintf(stderr, "Out of bounds I/O read: %d\n", addr);
return 0;
}
}
static void io_write(word addr, byte val)
{
addr &= 0xff;
IOWR fn = vm.iowr[addr];
if (fn != NULL) {
fn(val);
} else {
fprintf(stderr, "Out of bounds I/O write: %d / %d (0x%x)\n", addr, val, val);
}
}
// I/O hook to read/write a chunk of 1024 byte to blkfs at specified blkid.
// This is used by EFS@ and EFS! in xcomp.fs.
// See comment above BLK_PORT define for poking convention.
static void iowr_blk(byte val)
{
blkop <<= 8;
blkop |= val;
byte rw = blkop >> 32;
if (rw) {
word blkid = (blkop >> 16);
word dest = blkop & 0xffff;
blkop = 0;
fseek(blkfp, blkid*1024, SEEK_SET);
if (rw==2) { // write
fwrite(&vm.mem[dest], 1024, 1, blkfp);
} else { // read
fread(&vm.mem[dest], 1024, 1, blkfp);
}
}
}
// get/set word from/to memory
static word gw(word addr) { return vm.mem[addr+(word)1] << 8 | vm.mem[addr]; }
static void sw(word addr, word val) {
vm.mem[addr] = val;
vm.mem[addr+(word)1] = val >> 8;
}
// pop word from SP
static word pop() {
if (vm.uflw) return 0;
if (vm.SP >= SP_ADDR) { vm.uflw = true; return 0; }
return vm.mem[vm.SP++] | vm.mem[vm.SP++] << 8;
}
// push word to SP
static void push(word x) {
vm.SP -= 2;
if (vm.SP <= vm.RS) {
vm.oflw = true; vm.SP = SP_ADDR; vm.RS = RS_ADDR;
return;
}
sw(vm.SP, x);
if (vm.SP < vm.minSP) { vm.minSP = vm.SP; }
}
// pop word from RS
static word popRS() {
if (vm.uflw) return 0;
if (vm.RS <= RS_ADDR) { vm.uflw = true; return 0; }
word x = gw(vm.RS); vm.RS -= 2; return x;
}
// push word to RS
static void pushRS(word val) {
vm.RS += 2;
if (vm.SP <= vm.RS) {
vm.oflw = true; vm.SP = SP_ADDR; vm.RS = RS_ADDR;
return;
}
sw(vm.RS, val);
if (vm.RS > vm.maxRS) { vm.maxRS = vm.RS; }
}
// The functions below directly map to native forth words defined in the
// dictionary (doc/dict.txt)
static void execute(word wordref) {
byte wtype = vm.mem[wordref];
switch (wtype) {
case 0: // native
vm.nativew[vm.mem[wordref+(word)1]]();
break;
case 1: // compiled
pushRS(vm.IP);
vm.IP = wordref+1;
break;
case 2: // cell
push(wordref+1);
break;
case 3: // does
push(wordref+1);
pushRS(vm.IP);
vm.IP = gw(wordref+3);
break;
case 4: // alias
execute(gw(wordref+1));
break;
case 5: // switch
execute(gw(gw(wordref+1)));
break;
}
}
static word find(word daddr, word waddr) {
byte len = vm.mem[waddr];
waddr++;
while (1) {
if ((vm.mem[daddr-(word)1] & 0x7f) == len) {
word d = daddr-3-len;
// Sanity check
if ((waddr+len >= MEMSIZE) || (d+len) >= MEMSIZE) return 0;
if (strncmp(&vm.mem[waddr], &vm.mem[d], len) == 0) {
return daddr;
}
}
daddr -= 3;
word offset = gw(daddr);
if (offset) {
daddr -= offset;
} else {
return 0;
}
}
}
static void EXIT() { vm.IP = popRS(); }
static void _br_() {
word off = vm.mem[vm.IP];
if (off > 0x7f ) { off -= 0x100; }
vm.IP += off;
}
static void _cbr_() { if (!pop()) { _br_(); } else { vm.IP++; } }
static void _loop_() {
word I = gw(vm.RS); I++; sw(vm.RS, I);
if (I == gw(vm.RS-2)) { // don't branch
popRS(); popRS();
vm.IP++;
} else { // branch
_br_();
}
}
static void SP_to_R_2() { word x = pop(); pushRS(pop()); pushRS(x); }
static void nlit() { push(gw(vm.IP)); vm.IP += 2; }
static void slit() { push(vm.IP); vm.IP += vm.mem[vm.IP] + 1; }
static void SP_to_R() { pushRS(pop()); }
static void R_to_SP() { push(popRS()); }
static void R_to_SP_2() { word x = popRS(); push(popRS()); push(x); }
static void EXECUTE() { execute(pop()); }
static void ROT() { // a b c -- b c a
word c = pop(); word b = pop(); word a = pop();
push(b); push(c); push(a);
}
static void ROTR() { // a b c -- c a b
word c = pop(); word b = pop(); word a = pop();
push(c); push(a); push(b);
}
static void DUP() { // a -- a a
word a = pop(); push(a); push(a);
}
static void CDUP() {
word a = pop(); push(a); if (a) { push(a); }
}
static void DROP() { pop(); }
static void SWAP() { // a b -- b a
word b = pop(); word a = pop();
push(b); push(a);
}
static void OVER() { // a b -- a b a
word b = pop(); word a = pop();
push(a); push(b); push(a);
}
static void PICK() {
word x = pop();
push(gw(vm.SP+x*2));
}
static void _roll_() { // "1 2 3 4 4 (roll)" --> "1 3 4 4"
word x = pop();
while (x) { vm.mem[vm.SP+x+(word)2] = vm.mem[vm.SP+x]; x--; }
}
static void DROP2() { pop(); pop(); }
static void DUP2() { // a b -- a b a b
word b = pop(); word a = pop();
push(a); push(b); push(a); push(b);
}
static void S0() { push(SP_ADDR); }
static void Saddr() { push(vm.SP); }
static void AND() { push(pop() & pop()); }
static void OR() { push(pop() | pop()); }
static void XOR() { push(pop() ^ pop()); }
static void NOT() { push(!pop()); }
static void PLUS() { push(pop() + pop()); }
static void MINUS() {
word b = pop(); word a = pop();
push(a - b);
}
static void MULT() { push(pop() * pop()); }
static void DIVMOD() {
word b = pop(); word a = pop();
push(a % b); push(a / b);
}
static void STORE() {
word a = pop(); word val = pop();
sw(a, val);
}
static void FETCH() { push(gw(pop())); }
static void CSTORE() {
word a = pop(); word val = pop();
vm.mem[a] = val;
}
static void CFETCH() { push(vm.mem[pop()]); }
static void IO_OUT() {
word a = pop(); word val = pop();
io_write(a, val);
}
static void IO_IN() { push(io_read(pop())); }
static void RI() { push(gw(vm.RS)); }
static void RI_() { push(gw(vm.RS-2)); }
static void RJ() { push(gw(vm.RS-4)); }
static void BYE() { vm.running = false; }
static void _resSP_() { vm.SP = SP_ADDR; }
static void _resRS_() { vm.RS = RS_ADDR; }
static void Seq() {
word s1 = pop(); word s2 = pop();
byte len = vm.mem[s1];
if (len == vm.mem[s2]) {
s1++; s2++;
push(strncmp(&vm.mem[s1], &vm.mem[s2], len) == 0);
} else {
push(0);
}
}
static void CMP() {
word b = pop(); word a = pop();
if (a == b) { push(0); } else if (a > b) { push(1); } else { push(-1); }
}
static void _find() {
word waddr = pop(); word daddr = pop();
daddr = find(daddr, waddr);
if (daddr) {
push(daddr); push(1);
} else {
push(waddr); push(0);
}
}
static void ZERO() { push(0); }
static void ONE() { push(1); }
static void MONE() { push(-1); }
static void PLUS1() { push(pop()+1); }
static void MINUS1() { push(pop()-1); }
static void MINUS2() { push(pop()-2); }
static void PLUS2() { push(pop()+2); }
static void RSHIFT() { word u = pop(); push(pop()>>u); }
static void LSHIFT() { word u = pop(); push(pop()<<u); }
static void TICKS() { usleep(pop()); }
static void SPLITL() {
word n = pop(); push(n>>8); push(n&0xff); }
static void SPLITM() {
word n = pop(); push(n&0xff); push(n>>8); }
static void native(NativeWord func) {
vm.nativew[vm.nativew_count++] = func;
}
VM* VM_init(char *bin_path, char *blkfs_path)
{
fprintf(stderr, "Using blkfs %s\n", blkfs_path);
blkfp = fopen(blkfs_path, "r+");
if (!blkfp) {
fprintf(stderr, "Can't open\n");
return NULL;
}
fseek(blkfp, 0, SEEK_END);
if (ftell(blkfp) < 100 * 1024) {
fclose(blkfp);
fprintf(stderr, "emul/blkfs too small, something's wrong, aborting.\n");
return NULL;
}
fseek(blkfp, 0, SEEK_SET);
FILE *bfp = fopen(bin_path, "r");
if (!bfp) {
fprintf(stderr, "Can't open forth.bin\n");
return NULL;
}
int i = 0;
int c = getc(bfp);
while (c != EOF) {
vm.mem[i++] = c;
c = getc(bfp);
}
fclose(bfp);
// initialize rest of memory with random data. Many, many bugs we've seen in
// Collapse OS were caused by bad initialization and weren't reproducable
// in CVM because it has a neat zeroed-out memory. Let's make bugs easier
// to spot.
while (i<0x10000) {
vm.mem[i++] = random();
}
vm.SP = SP_ADDR;
vm.RS = RS_ADDR;
vm.minSP = SP_ADDR;
vm.maxRS = RS_ADDR;
vm.nativew_count = 0;
for (int i=0; i<0x100; i++) {
vm.iord[i] = NULL;
vm.iowr[i] = NULL;
}
vm.iowr[BLK_PORT] = iowr_blk;
// Added in the same order as in xcomp.fs
native(EXIT);
native(_br_);
native(_cbr_);
native(_loop_);
native(nlit);
native(slit);
native(SP_to_R);
native(R_to_SP);
native(SP_to_R_2);
native(R_to_SP_2);
native(EXECUTE);
native(ROT);
native(DUP);
native(CDUP);
native(DROP);
native(SWAP);
native(OVER);
native(PICK);
native(_roll_);
native(DROP2);
native(DUP2);
native(S0);
native(Saddr);
native(AND);
native(OR);
native(XOR);
native(NOT);
native(PLUS);
native(MINUS);
native(MULT);
native(DIVMOD);
native(STORE);
native(FETCH);
native(CSTORE);
native(CFETCH);
native(IO_OUT);
native(IO_IN);
native(RI);
native(RI_);
native(RJ);
native(BYE);
native(_resSP_);
native(_resRS_);
native(Seq);
native(CMP);
native(_find);
native(ZERO);
native(ONE);
native(MONE);
native(PLUS1);
native(MINUS1);
native(PLUS2);
native(MINUS2);
native(RSHIFT);
native(LSHIFT);
native(TICKS);
native(ROTR);
native(SPLITL);
native(SPLITM);
vm.IP = gw(0x04) + 1; // BOOT
sw(SYSVARS+0x02, gw(0x08)); // CURRENT
sw(SYSVARS+0x04, gw(0x08)); // HERE
vm.uflw = false;
vm.oflw = false;
vm.running = true;
return &vm;
}
void VM_deinit()
{
fclose(blkfp);
}
bool VM_steps(int n) {
if (!vm.running) {
fprintf(stderr, "machine halted!\n");
return false;
}
while (n && vm.running) {
word wordref = gw(vm.IP);
vm.IP += 2;
execute(wordref);
if (vm.uflw) {
vm.uflw = false;
execute(gw(0x06)); /* uflw */
}
if (vm.oflw) {
vm.oflw = false;
execute(gw(0x13)); /* oflw */
}
n--;
}
return vm.running;
}
void VM_memdump() {
fprintf(stderr, "Dumping memory to memdump. IP %04x\n", vm.IP);
FILE *fp = fopen("memdump", "w");
fwrite(vm.mem, 0x10000, 1, fp);
fclose(fp);
}
void VM_debugstr(char *s) {
sprintf(s, "SP %04x (%04x) RS %04x (%04x)",
vm.SP, vm.minSP, vm.RS, vm.maxRS);
}
void VM_printdbg() {
char buf[0x100];
VM_debugstr(buf);
fprintf(stderr, "%s\n", buf);
}