561 lines
13 KiB
C
561 lines
13 KiB
C
/* RETRO -------------------------------------------------------------
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A personal, minimalistic forth
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Copyright (c) 2016 - 2019 Charles Childers
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This is the `repl`, a basic interactive interface for RETRO. It is
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intended to be simple and very minimalistic, providing the minimal
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I/O and additions needed to support a basic RETRO system. For a much
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larger system, see `rre`.
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I'll include commentary throughout the source, so read on.
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---------------------------------------------------------------------*/
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#include <sys/types.h>
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#include "image.c"
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int getchar(void);
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int putchar(int c);
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long stack_pop();
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void stack_push(long value);
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int remap(int c) {
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int a = c;
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#ifdef USE_DVORAK
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switch (c) {
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case 'q': a = '\''; break; case 'Q': a = '"'; break;
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case 'w': a = ','; break; case 'W': a = '<'; break;
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case 'e': a = '.'; break; case 'E': a = '>'; break;
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case 'r': a = 'p'; break; case 'R': a = 'P'; break;
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case 't': a = 'y'; break; case 'T': a = 'Y'; break;
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case 'y': a = 'f'; break; case 'Y': a = 'F'; break;
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case 'u': a = 'g'; break; case 'U': a = 'G'; break;
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case 'i': a = 'c'; break; case 'I': a = 'C'; break;
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case 'o': a = 'r'; break; case 'O': a = 'R'; break;
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case 'p': a = 'l'; break; case 'P': a = 'L'; break;
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case '[': a = '/'; break; case '{': a = '?'; break;
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case ']': a = '='; break; case '}': a = '+'; break;
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case 'a': a = 'a'; break; case 'A': a = 'A'; break;
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case 's': a = 'o'; break; case 'S': a = 'O'; break;
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case 'd': a = 'e'; break; case 'D': a = 'E'; break;
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case 'f': a = 'u'; break; case 'F': a = 'U'; break;
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case 'g': a = 'i'; break; case 'G': a = 'I'; break;
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case 'h': a = 'd'; break; case 'H': a = 'D'; break;
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case 'j': a = 'h'; break; case 'J': a = 'H'; break;
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case 'k': a = 't'; break; case 'K': a = 'T'; break;
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case 'l': a = 'n'; break; case 'L': a = 'N'; break;
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case ';': a = 's'; break; case ':': a = 'S'; break;
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case '\'': a = '-'; break; case '"': a = '_'; break;
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case 'z': a = ';'; break; case 'Z': a = ':'; break;
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case 'x': a = 'q'; break; case 'X': a = 'Q'; break;
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case 'c': a = 'j'; break; case 'C': a = 'J'; break;
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case 'v': a = 'k'; break; case 'V': a = 'K'; break;
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case 'b': a = 'x'; break; case 'B': a = 'X'; break;
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case 'n': a = 'b'; break; case 'N': a = 'B'; break;
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case 'm': a = 'm'; break; case 'M': a = 'M'; break;
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case ',': a = 'w'; break; case '<': a = 'W'; break;
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case '.': a = 'v'; break; case '>': a = 'V'; break;
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case '/': a = 'z'; break; case '?': a = 'Z'; break;
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case '-': a = '['; break; case '_': a = '{'; break;
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case '=': a = ']'; break; case '+': a = '}'; break;
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}
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#endif
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return a;
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}
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unsigned char inportb(unsigned int port)
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{
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unsigned char ret;
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asm volatile ("inb %%dx,%%al":"=a" (ret):"d" (port));
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return ret;
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}
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void outportb(unsigned int port,unsigned char value)
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{
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asm volatile ("outb %%al,%%dx": :"d" (port), "a" (value));
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}
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void store() {
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long address = stack_pop();
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long value = stack_pop();
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*((int*)address) = value;
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}
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void fetch() {
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stack_push(*((int*)stack_pop()));
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}
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void storeb() {
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long address = stack_pop();
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long value = stack_pop();
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*((char *)address) = (char)value;
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}
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void fetchb() {
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stack_push((long)*((char*)stack_pop()) & 0xFF);
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}
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static inline uint16_t inw(uint16_t port)
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{
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uint16_t ret;
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asm volatile ( "inw %1, %0"
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: "=a"(ret)
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: "Nd"(port) );
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return ret;
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}
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static inline void outw(uint16_t port, uint16_t val)
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{
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asm volatile ( "outw %0, %1" : : "a"(val), "Nd"(port) );
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}
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/*---------------------------------------------------------------------
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Next we get into some things that relate to the Nga virtual machine
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that RETRO runs on.
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---------------------------------------------------------------------*/
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#define CELL long /* Cell size (32 bit, signed integer */
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#define IMAGE_SIZE 524288 * 8 /* Amount of RAM. 4MiB by default. */
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#define ADDRESSES 1024 /* Depth of address stack */
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#define STACK_DEPTH 128 /* Depth of data stack */
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CELL sp, rp, ip; /* Data, address, instruction pointers */
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CELL data[STACK_DEPTH]; /* The data stack */
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CELL address[ADDRESSES]; /* The address stack */
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CELL memory[IMAGE_SIZE + 1]; /* The memory for the image */
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#define TOS data[sp] /* Shortcut for top item on stack */
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#define NOS data[sp-1] /* Shortcut for second item on stack */
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#define TORS address[rp] /* Shortcut for top item on address stack */
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#ifdef TARGET_X86
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#define NUM_DEVICES 3
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#else
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#define NUM_DEVICES 2
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#endif
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typedef void (*Handler)(void);
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Handler IO_deviceHandlers[NUM_DEVICES + 1];
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Handler IO_queryHandlers[NUM_DEVICES + 1];
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/*---------------------------------------------------------------------
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Function prototypes.
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---------------------------------------------------------------------*/
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void execute(int cell);
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CELL ngaLoadImage(char *imageFile);
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void ngaPrepare();
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void ngaProcessOpcode(CELL opcode);
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void ngaProcessPackedOpcodes(CELL opcode);
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int ngaValidatePackedOpcodes(CELL opcode);
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/*---------------------------------------------------------------------
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Now to the fun stuff: interfacing with the virtual machine. There are
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a things I like to have here:
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- push a value to the stack
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- pop a value off the stack
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- extract a string from the image
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- inject a string into the image.
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- lookup dictionary headers and access dictionary fields
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---------------------------------------------------------------------*/
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/*---------------------------------------------------------------------
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Stack push/pop is easy. I could avoid these, but it aids in keeping
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the code readable, so it's worth the slight overhead.
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---------------------------------------------------------------------*/
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CELL stack_pop() {
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sp--;
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return data[sp + 1];
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}
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void stack_push(CELL value) {
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sp++;
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data[sp] = value;
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}
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/*---------------------------------------------------------------------
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This is an implementation of the generic output device. It's set to
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write output to the standard display.
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---------------------------------------------------------------------*/
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void generic_output() {
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stack_pop();
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}
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void generic_output_query() {
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stack_push(0);
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stack_push(0);
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}
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#ifdef TARGET_X86
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void portio() {
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CELL p, v;
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switch (stack_pop()) {
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case 0: stack_push((CELL)inportb((unsigned int)stack_pop()));
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break;
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case 1: p = stack_pop();
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v = stack_pop();
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outportb((unsigned int)p, (unsigned char)v);
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break;
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case 2: store();
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break;
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case 3: fetch();
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break;
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case 4: storeb();
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break;
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case 5: fetchb();
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break;
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case 6: stack_push((CELL)inw((uint16_t)stack_pop()));
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break;
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case 7: p = stack_pop();
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v = stack_pop();
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outw((uint16_t)p, (uint16_t)v);
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break;
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}
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}
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void portio_query() {
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stack_push(0);
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stack_push(2000);
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}
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#endif
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void generic_input() {
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stack_push(remap(getchar()));
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if (TOS == 127) TOS = 8;
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}
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void generic_input_query() {
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stack_push(0);
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stack_push(1);
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}
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/*---------------------------------------------------------------------
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With these out of the way, I implement `execute`, which takes an
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address and runs the code at it. This has a couple of interesting
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bits.
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Nga uses packed instruction bundles, with up to four instructions per
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bundle. Since RETRO requires an additional instruction to handle
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displaying a character, I define the handler for that here.
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This will also exit if the address stack depth is zero (meaning that
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the word being run, and it's dependencies) are finished.
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---------------------------------------------------------------------*/
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void execute(int cell) {
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CELL opcode;
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rp = 1;
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ip = cell;
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while (ip < IMAGE_SIZE) {
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opcode = memory[ip];
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if (ngaValidatePackedOpcodes(opcode) != 0) {
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ngaProcessPackedOpcodes(opcode);
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} else {
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while(1);
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}
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ip++;
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if (rp == 0)
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ip = IMAGE_SIZE;
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}
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}
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/*---------------------------------------------------------------------
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The `main()` routine. This sets up the Nga VM, loads the image, and
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enters a loop.
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The loop:
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- reads input
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- otherwise, pass to `evaluate()` to run
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---------------------------------------------------------------------*/
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int main(int argc, char **argv) {
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IO_deviceHandlers[0] = generic_output;
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IO_queryHandlers[0] = generic_output_query;
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IO_deviceHandlers[1] = generic_input;
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IO_queryHandlers[1] = generic_input_query;
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#ifdef TARGET_X86
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IO_deviceHandlers[2] = portio;
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IO_queryHandlers[2] = portio_query;
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#endif
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while (1) {
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ngaPrepare();
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for (CELL i = 0; i < ngaImageCells; i++)
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memory[i] = ngaImage[i];
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execute(0);
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}
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}
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/* Nga ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Copyright (c) 2008 - 2019, Charles Childers
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Copyright (c) 2009 - 2010, Luke Parrish
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Copyright (c) 2010, Marc Simpson
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Copyright (c) 2010, Jay Skeer
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Copyright (c) 2011, Kenneth Keating
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
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enum vm_opcode {
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VM_NOP, VM_LIT, VM_DUP, VM_DROP, VM_SWAP, VM_PUSH, VM_POP,
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VM_JUMP, VM_CALL, VM_CCALL, VM_RETURN, VM_EQ, VM_NEQ, VM_LT,
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VM_GT, VM_FETCH, VM_STORE, VM_ADD, VM_SUB, VM_MUL, VM_DIVMOD,
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VM_AND, VM_OR, VM_XOR, VM_SHIFT, VM_ZRET, VM_END, VM_IE,
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VM_IQ, VM_II
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};
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#define NUM_OPS VM_II + 1
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#ifndef NUM_DEVICES
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#define NUM_DEVICES 0
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#endif
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CELL ngaLoadImage(char *imageFile) {
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CELL i;
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for (i = 0; i < ngaImageCells; i++)
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memory[i] = ngaImage[i];
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return i;
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}
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void ngaPrepare() {
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ip = sp = rp = 0;
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for (ip = 0; ip < IMAGE_SIZE; ip++)
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memory[ip] = VM_NOP;
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for (ip = 0; ip < STACK_DEPTH; ip++)
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data[ip] = 0;
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for (ip = 0; ip < ADDRESSES; ip++)
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address[ip] = 0;
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}
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void inst_nop() {
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}
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void inst_lit() {
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sp++;
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ip++;
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TOS = memory[ip];
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}
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void inst_dup() {
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sp++;
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data[sp] = NOS;
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}
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void inst_drop() {
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data[sp] = 0;
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if (--sp < 0)
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ip = IMAGE_SIZE;
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}
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void inst_swap() {
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CELL a;
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a = TOS;
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TOS = NOS;
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NOS = a;
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}
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void inst_push() {
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rp++;
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TORS = TOS;
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inst_drop();
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}
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void inst_pop() {
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sp++;
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TOS = TORS;
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rp--;
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}
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void inst_jump() {
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ip = TOS - 1;
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inst_drop();
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}
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void inst_call() {
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rp++;
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TORS = ip;
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ip = TOS - 1;
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inst_drop();
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}
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void inst_ccall() {
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CELL a, b;
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a = TOS; inst_drop(); /* False */
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b = TOS; inst_drop(); /* Flag */
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if (b != 0) {
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rp++;
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TORS = ip;
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ip = a - 1;
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}
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}
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void inst_return() {
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ip = TORS;
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rp--;
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}
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void inst_eq() {
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NOS = (NOS == TOS) ? -1 : 0;
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inst_drop();
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}
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void inst_neq() {
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NOS = (NOS != TOS) ? -1 : 0;
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inst_drop();
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}
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void inst_lt() {
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NOS = (NOS < TOS) ? -1 : 0;
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inst_drop();
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}
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void inst_gt() {
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NOS = (NOS > TOS) ? -1 : 0;
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inst_drop();
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}
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void inst_fetch() {
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switch (TOS) {
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case -1: TOS = sp - 1; break;
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case -2: TOS = rp; break;
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case -3: TOS = IMAGE_SIZE; break;
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default: TOS = memory[TOS]; break;
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}
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}
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void inst_store() {
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if (TOS <= IMAGE_SIZE && TOS >= 0) {
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memory[TOS] = NOS;
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inst_drop();
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inst_drop();
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} else {
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ip = IMAGE_SIZE;
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}
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}
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void inst_add() {
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NOS += TOS;
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inst_drop();
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}
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void inst_sub() {
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NOS -= TOS;
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inst_drop();
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}
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void inst_mul() {
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NOS *= TOS;
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inst_drop();
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}
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void inst_divmod() {
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CELL a, b;
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a = TOS;
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b = NOS;
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TOS = b / a;
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NOS = b % a;
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}
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void inst_and() {
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NOS = TOS & NOS;
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inst_drop();
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}
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void inst_or() {
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NOS = TOS | NOS;
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inst_drop();
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}
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void inst_xor() {
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NOS = TOS ^ NOS;
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inst_drop();
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}
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void inst_shift() {
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CELL y = TOS;
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CELL x = NOS;
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if (TOS < 0)
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NOS = NOS << (TOS * -1);
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else {
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if (x < 0 && y > 0)
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NOS = x >> y | ~(~0U >> y);
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else
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NOS = x >> y;
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}
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inst_drop();
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}
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void inst_zret() {
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if (TOS == 0) {
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inst_drop();
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ip = TORS;
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rp--;
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}
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}
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void inst_end() {
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ip = IMAGE_SIZE;
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}
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void inst_ie() {
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sp++;
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TOS = NUM_DEVICES;
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}
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void inst_iq() {
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CELL Device = TOS;
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inst_drop();
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IO_queryHandlers[Device]();
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}
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void inst_ii() {
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CELL Device = TOS;
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inst_drop();
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IO_deviceHandlers[Device]();
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}
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Handler instructions[NUM_OPS] = {
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inst_nop, inst_lit, inst_dup, inst_drop, inst_swap, inst_push, inst_pop,
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inst_jump, inst_call, inst_ccall, inst_return, inst_eq, inst_neq, inst_lt,
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inst_gt, inst_fetch, inst_store, inst_add, inst_sub, inst_mul, inst_divmod,
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inst_and, inst_or, inst_xor, inst_shift, inst_zret, inst_end, inst_ie,
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inst_iq, inst_ii
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};
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void ngaProcessOpcode(CELL opcode) {
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if (opcode != 0)
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instructions[opcode]();
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}
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int ngaValidatePackedOpcodes(CELL opcode) {
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CELL raw = opcode;
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CELL current;
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int valid = -1;
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int i;
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for (i = 0; i < 4; i++) {
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current = raw & 0xFF;
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if (!(current >= 0 && current <= 29))
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valid = 0;
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raw = raw >> 8;
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}
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return valid;
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}
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void ngaProcessPackedOpcodes(CELL opcode) {
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CELL raw = opcode;
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int i;
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for (i = 0; i < 4; i++) {
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ngaProcessOpcode(raw & 0xFF);
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raw = raw >> 8;
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}
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}
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