/*--------------------------------------------------------------------- RETRO is a personal, minimalistic forth with a pragmatic focus This implements Nga, the virtual machine at the heart of RETRO. It includes a number of I/O interfaces, extensive commentary, and has been refined by over a decade of use and development. Copyright (c) 2008 - 2020, Charles Childers Portions are based on Ngaro, which was additionally copyrighted by the following: Copyright (c) 2009 - 2010, Luke Parrish Copyright (c) 2010, Marc Simpson Copyright (c) 2010, Jay Skeer Copyright (c) 2011, Kenneth Keating ---------------------------------------------------------------------*/ /*--------------------------------------------------------------------- C Headers ---------------------------------------------------------------------*/ #include #include #include #include #include #include #include #include #include #include #include #include #include /*--------------------------------------------------------------------- Configuration ---------------------------------------------------------------------*/ #include "config.h" #include "prototypes.h" /*--------------------------------------------------------------------- Image, Stack, and VM variables ---------------------------------------------------------------------*/ CELL sp, rp, ip; /* Stack & instruction pointers */ CELL data[STACK_DEPTH]; /* The data stack */ CELL address[ADDRESSES]; /* The address stack */ CELL memory[IMAGE_SIZE + 1]; /* The memory for the image */ #define TOS data[sp] /* Shortcut for top item on stack */ #define NOS data[sp-1] /* Shortcut for second item on stack */ #define TORS address[rp] /* Shortcut for top item on address stack */ /*--------------------------------------------------------------------- Markers for code & test blocks ---------------------------------------------------------------------*/ char code_start[33], code_end[33], test_start[33], test_end[33]; /*--------------------------------------------------------------------- Populate The I/O Device Tables ---------------------------------------------------------------------*/ typedef void (*Handler)(void); Handler IO_deviceHandlers[] = { io_output_handler, io_keyboard_handler, io_floatingpoint_handler, io_filesystem_handler, io_clock_handler, io_unix_handler, io_scripting_handler, io_random, io_image, }; Handler IO_queryHandlers[] = { io_output_query, io_keyboard_query, io_floatingpoint_query, io_filesystem_query, io_clock_query, io_unix_query, io_scripting_query, io_random_query, io_image_query, }; /*--------------------------------------------------------------------- Variables Related To Image Introspection ---------------------------------------------------------------------*/ CELL Compiler; CELL Dictionary; CELL NotFound; CELL interpret; /*--------------------------------------------------------------------- Global Variables ---------------------------------------------------------------------*/ char string_data[8192]; char **sys_argv; int sys_argc; int silence_input; char scripting_sources[64][8192]; int current_source; /*--------------------------------------------------------------------- Embed The Image and Devices ---------------------------------------------------------------------*/ #include "retro-image.c" #include "bsd-strl.c" #include "dev-floatingpoint.c" #include "dev-image.c" #include "dev-files.c" #include "dev-unix.c" #include "dev-clock.c" #include "dev-rng.c" /*--------------------------------------------------------------------- Now on to I/O and extensions! RRE provides a lot of additional functionality over the base RETRO system. First up is support for files. The RRE file model is intended to be similar to that of the standard C libraries and wraps fopen(), fclose(), etc. ---------------------------------------------------------------------*/ void io_output_handler() { putc(stack_pop(), stdout); fflush(stdout); } void io_output_query() { stack_push(0); stack_push(0); } /*=====================================================================*/ void io_keyboard_handler() { stack_push(getc(stdin)); if (TOS == 127) TOS = 8; } void io_keyboard_query() { stack_push(0); stack_push(1); } /*=====================================================================*/ /*--------------------------------------------------------------------- Scripting Support ---------------------------------------------------------------------*/ CELL currentLine; CELL ignoreToEOL; CELL ignoreToEOF; void scripting_arg() { CELL a, b; a = stack_pop(); b = stack_pop(); stack_push(string_inject(sys_argv[a + 2], b)); } void scripting_arg_count() { stack_push(sys_argc - 2); } void scripting_include() { include_file(string_extract(stack_pop()), 0); } void scripting_name() { stack_push(string_inject(sys_argv[1], stack_pop())); } /* addeded in scripting i/o device, revision 1 */ void scripting_source() { stack_push(string_inject(scripting_sources[current_source], stack_pop())); } void scripting_line() { stack_push(currentLine + 1); } void scripting_ignore_to_eol() { ignoreToEOL = -1; } void scripting_ignore_to_eof() { ignoreToEOF = -1; } Handler ScriptingActions[] = { scripting_arg_count, scripting_arg, scripting_include, scripting_name, scripting_source, scripting_line, scripting_ignore_to_eol, scripting_ignore_to_eof }; void io_scripting_query() { stack_push(1); stack_push(9); } void io_scripting_handler() { ScriptingActions[stack_pop()](); } /*=====================================================================*/ /*--------------------------------------------------------------------- With these out of the way, I implement `execute`, which takes an address and runs the code at it. This has a couple of interesting bits. This will also exit if the address stack depth is zero (meaning that the word being run, and it's dependencies) are finished. ---------------------------------------------------------------------*/ void execute(CELL cell, int silent) { CELL a, b, i, token; CELL opcode; silence_input = silent; rp = 1; ip = cell; token = TIB; while (ip < IMAGE_SIZE) { if (ip == NotFound) { printf("\nERROR: Word Not Found: "); printf("`%s`\n\n", string_extract(token)); } if (ip == interpret) { token = TOS; } opcode = memory[ip]; if (ngaValidatePackedOpcodes(opcode) != 0) { ngaProcessPackedOpcodes(opcode); } else { printf("\nERROR (nga/execute): Invalid instruction!\n"); printf("At %lld, opcode %lld\n", (long long)ip, (long long)opcode); printf("Instructions: "); a = opcode; for (i = 0; i < 4; i++) { b = a & 0xFF; printf("%lldd ", (long long)b); a = a >> 8; } printf("\n"); exit(1); } #ifndef NOCHECKS if (sp < 0 || sp > STACK_DEPTH) { printf("\nERROR (nga/execute): Stack Limits Exceeded!\n"); printf("At %lld, opcode %lld. sp = %lld\n", (long long)ip, (long long)opcode, (long long)sp); exit(1); } if (rp < 0 || rp > ADDRESSES) { printf("\nERROR (nga/execute): Address Stack Limits Exceeded!\n"); printf("At %lld, opcode %lld. rp = %lld\n", (long long)ip, (long long)opcode, (long long)rp); } #endif ip++; if (rp == 0) ip = IMAGE_SIZE; } } /*--------------------------------------------------------------------- RETRO's `interpret` word expects a token on the stack. This next function copies a token to the `TIB` (text input buffer) and then calls `interpret` to process it. ---------------------------------------------------------------------*/ void evaluate(char *s, int silent) { if (strlen(s) == 0) return; string_inject(s, TIB); stack_push(TIB); execute(interpret, silent); } /*--------------------------------------------------------------------- `read_token` reads a token from the specified file. It will stop on a whitespace or newline. It also tries to handle backspaces, though the success of this depends on how your terminal is configured. ---------------------------------------------------------------------*/ int not_eol(int c) { return (c != 10) && (c != 13) && (c != 32) && (c != EOF) && (c != 0); } void read_token(FILE *file, char *token_buffer, int echo) { int ch = getc(file); int count = 0; if (echo != 0) putchar(ch); while (not_eol(ch)) { if ((ch == 8 || ch == 127) && count > 0) { count--; if (echo != 0) { putchar(8); putchar(32); putchar(8); } } else { token_buffer[count++] = ch; } ch = getc(file); if (echo != 0) putchar(ch); } token_buffer[count] = '\0'; } /*--------------------------------------------------------------------- Display the Stack Contents ---------------------------------------------------------------------*/ void dump_stack() { CELL i; if (sp == 0) return; printf("\nStack: "); for (i = 1; i <= sp; i++) { if (i == sp) printf("[ TOS: %lld ]", (long long)data[i]); else printf("%lld ", (long long)data[i]); } printf("\n"); } /*--------------------------------------------------------------------- RRE is primarily intended to be used in a batch or scripting model. The `include_file()` function will be used to read the code in the file, evaluating it as encountered. I enforce a literate model, with code in fenced blocks. E.g., # This is a test Display "Hello, World!" ~~~ 'Hello,_World! puts nl ~~~ RRE will ignore anything outside the `~~~` blocks. To identify if the current token is the start or end of a block, I provide a `fenced()` function. ---------------------------------------------------------------------*/ int fenced(char *s) { int a = strcmp(s, "```"); int b = strcmp(s, "~~~"); if (a == 0) return 2; if (b == 0) return 1; return 0; } /* Check to see if a line is a fence boundary. This will check code blocks in all cases, and test blocks if tests_enabled is set to a non-zero value. */ int fence_boundary(char *buffer, int tests_enabled) { int flag = 1; if (strcmp(buffer, code_start) == 0) { flag = -1; } if (strcmp(buffer, code_end) == 0) { flag = -1; } if (tests_enabled == 0) { return flag; } if (strcmp(buffer, test_start) == 0) { flag = -1; } if (strcmp(buffer, test_end) == 0) { flag = -1; } return flag; } /*--------------------------------------------------------------------- And now for the actual `include_file()` function. ---------------------------------------------------------------------*/ void read_line(FILE *file, char *token_buffer) { int ch = getc(file); int count = 0; while ((ch != 10) && (ch != 13) && (ch != EOF) && (ch != 0)) { token_buffer[count++] = ch; ch = getc(file); } token_buffer[count] = '\0'; } int count_tokens(char *line) { char ch = line[0]; int count = 1; while (*line++) { ch = line[0]; if (isspace(ch)) count++; } return count; } void include_file(char *fname, int run_tests) { int inBlock = 0; /* Tracks status of in/out of block */ char source[64 * 1024]; /* Token buffer [about 64K] */ char line[64 * 1024]; /* Line buffer [about 64K] */ char fence[33]; /* Used with `fence_boundary()` */ long offset = 0; CELL at = 0; int tokens = 0; FILE *fp; /* Open the file. If not found, */ fp = fopen(fname, "r"); /* exit. */ if (fp == NULL) return; current_source++; bsd_strlcpy(scripting_sources[current_source], fname, 8192); ignoreToEOF = 0; while (!feof(fp) && (ignoreToEOF == 0)) { /* Loop through the file */ ignoreToEOL = 0; offset = ftell(fp); read_line(fp, line); fseek(fp, offset, SEEK_SET); tokens = count_tokens(line); while (tokens > 0 && ignoreToEOL == 0) { tokens--; read_token(fp, source, 0); bsd_strlcpy(fence, source, 32); /* Copy the first three characters */ if (fence_boundary(fence, run_tests) == -1) { if (inBlock == 0) inBlock = 1; else inBlock = 0; } else { if (inBlock == 1) { currentLine = at; evaluate(source, -1); currentLine = at; } } } if (ignoreToEOL == -1) read_line(fp, line); at++; } current_source--; ignoreToEOF = 0; fclose(fp); } /*--------------------------------------------------------------------- `help()` displays a summary of the command line arguments RRE allows. This is invoked using `rre -h` ---------------------------------------------------------------------*/ void help(char *exename) { printf("Scripting Usage: %s filename\n\n", exename); printf("Interactive Usage: %s [-h] [-i] [-f filename] [-t]\n\n", exename); printf("Valid Arguments:\n\n"); printf(" -h\n"); printf(" Display this help text\n"); printf(" -i\n"); printf(" Launches in interactive mode\n"); printf(" -s\n"); printf(" Suppress the startup banner in interactive mode. Implies -i.\n"); printf(" -f filename\n"); printf(" Run the contents of the specified file\n"); printf(" -u filename\n"); printf(" Use the image in the specified file instead of the internal one\n"); printf(" -r filename\n"); printf(" Use the image in the specified file instead of the internal one and run the code in it\n"); printf(" -t\n"); printf(" Run tests (in ``` blocks) in any loaded files\n\n"); } /*--------------------------------------------------------------------- `initialize()` sets up Nga and loads the image (from the array in `image.c`) to memory. ---------------------------------------------------------------------*/ void initialize() { CELL i; ngaPrepare(); for (i = 0; i < ngaImageCells; i++) memory[i] = ngaImage[i]; } /*--------------------------------------------------------------------- `arg_is()` exists to aid in readability. It compares the first actual command line argument to a string and returns a boolean flag. ---------------------------------------------------------------------*/ int arg_is(char *argv, char *t) { return strcmp(argv, t) == 0; } /*--------------------------------------------------------------------- Main Entry Point ---------------------------------------------------------------------*/ enum flags { FLAG_HELP, FLAG_RUN_TESTS, FLAG_INCLUDE, FLAG_INTERACTIVE, FLAG_SILENT, FLAG_RUN, }; int main(int argc, char **argv) { int i; int modes[16]; char *files[16]; int fsp; int run_tests; initialize(); /* Initialize Nga & image */ strcpy(code_start, "~~~"); strcpy(code_end, "~~~"); strcpy(test_start, "```"); strcpy(test_end, "```"); /* Setup variables related to the scripting device */ currentLine = 0; /* Current Line # for script */ current_source = 0; /* Current file being run */ sys_argc = argc; /* Point the global argc and */ sys_argv = argv; /* argv to the actual ones */ bsd_strlcpy(scripting_sources[0], "/dev/stdin", 8192); ignoreToEOL = 0; ignoreToEOF = 0; if (argc >= 2 && argv[1][0] != '-') { update_rx(); include_file(argv[1], 0); /* If no flags were passed, */ if (sp >= 1) dump_stack(); /* load the file specified, */ exit(0); /* and exit */ } /* Clear startup modes */ for (i = 0; i < 16; i++) modes[i] = 0; /* Clear startup files */ for (i = 0; i < 16; i++) files[i] = "\0"; fsp = 0; run_tests = 0; if (argc <= 1) modes[FLAG_INTERACTIVE] = 1; /* Process Arguments */ for (i = 1; i < argc; i++) { if (strcmp(argv[i], "-h") == 0) { help(argv[0]); exit(0); } else if (strcmp(argv[i], "-i") == 0) { modes[FLAG_INTERACTIVE] = 1; } else if (strcmp(argv[i], "-s") == 0) { modes[FLAG_INTERACTIVE] = 1; modes[FLAG_SILENT] = 1; } else if (strcmp(argv[i], "-f") == 0) { files[fsp] = argv[i + 1]; fsp++; i++; } else if (strcmp(argv[i], "-u") == 0) { i++; ngaLoadImage(argv[i]); } else if (strcmp(argv[i], "-r") == 0) { i++; ngaLoadImage(argv[i]); modes[FLAG_RUN] = 1; } else if (strcmp(argv[i], "-t") == 0) { modes[FLAG_RUN_TESTS] = 1; run_tests = 1; } else if (arg_is(argv[i], "--code-start") || arg_is(argv[i], "-cs")) { i++; strcpy(code_start, argv[i]); } else if (arg_is(argv[i], "--code-end") || arg_is(argv[i], "-ce")) { i++; strcpy(code_end, argv[i]); } else if (arg_is(argv[i], "--test-start") || arg_is(argv[i], "-ts")) { i++; strcpy(test_start, argv[i]); } else if (arg_is(argv[i], "--test-end") || arg_is(argv[i], "-te")) { i++; strcpy(test_end, argv[i]); } } update_rx(); /* Include Startup Files */ for (i = 0; i < fsp; i++) { if (strcmp(files[i], "\0") != 0) include_file(files[i], run_tests); } /* Set Image Flags for NoEcho if started with `-s` */ if (modes[FLAG_SILENT] == 1) memory[d_xt_for("NoEcho", Dictionary)] = -1; /* Run the Listener (if interactive mode was set) */ if (modes[FLAG_INTERACTIVE] == 1) { while (1) execute(0, -1); } if (modes[FLAG_RUN] == 1) { execute(0, -1); } } /*=====================================================================*/ /*=====================================================================*/ /*--------------------------------------------------------------------- Interfacing With The Image ---------------------------------------------------------------------*/ /*--------------------------------------------------------------------- Stack push/pop is easy. I could avoid these, but it aids in keeping the code readable, so it's worth the slight overhead. ---------------------------------------------------------------------*/ CELL stack_pop() { sp--; #ifndef NOCHECKS if (sp < 0) { printf("\nERROR (nga/stack_pop): Data stack underflow.\n"); exit(1); } #endif return data[sp + 1]; } void stack_push(CELL value) { sp++; #ifndef NOCHECKS if (sp >= STACK_DEPTH) { printf("\nERROR (nga/stack_push): Data stack overflow.\n"); exit(1); } #endif data[sp] = value; } /*--------------------------------------------------------------------- Strings are next. RETRO uses C-style NULL terminated strings. So I can easily inject or extract a string. Injection iterates over the string, copying it into the image. This also takes care to ensure that the NULL terminator is added. ---------------------------------------------------------------------*/ CELL string_inject(char *str, CELL buffer) { CELL m, i; if (!str) { memory[buffer] = 0; return 0; } m = strlen(str); i = 0; while (m > 0) { memory[buffer + i] = (CELL)str[i]; memory[buffer + i + 1] = 0; m--; i++; } return buffer; } /*--------------------------------------------------------------------- Extracting a string is similar, but I have to iterate over the VM memory instead of a C string and copy the charaters into a buffer. This uses a static buffer (`string_data`) as I prefer to avoid using `malloc()`. ---------------------------------------------------------------------*/ char *string_extract(CELL at) { CELL starting = at; CELL i = 0; while(memory[starting] && i < 8192) string_data[i++] = (char)memory[starting++]; string_data[i] = 0; return (char *)string_data; } /*--------------------------------------------------------------------- Continuing along, I now define functions to access the dictionary. RETRO's dictionary is a linked list. Each entry is setup like: 0000 Link to previous entry (NULL if this is the root entry) 0001 Pointer to definition start 0002 Pointer to class handler 0003 Start of a NULL terminated string with the word name First, functions to access each field. The offsets were defineed at the start of the file. ---------------------------------------------------------------------*/ CELL d_link(CELL dt) { return dt + D_OFFSET_LINK; } CELL d_xt(CELL dt) { return dt + D_OFFSET_XT; } CELL d_class(CELL dt) { return dt + D_OFFSET_CLASS; } CELL d_name(CELL dt) { return dt + D_OFFSET_NAME; } /*--------------------------------------------------------------------- Next, a more complext word. This will walk through the entries to find one with a name that matches the specified name. This is *slow*, but works ok unless you have a really large dictionary. (I've not run into issues with this in practice). ---------------------------------------------------------------------*/ CELL d_lookup(CELL Dictionary, char *name) { CELL dt = 0; CELL i = Dictionary; char *dname; while (memory[i] != 0 && i != 0) { dname = string_extract(d_name(i)); if (strcmp(dname, name) == 0) { dt = i; i = 0; } else { i = memory[i]; } } return dt; } /*--------------------------------------------------------------------- My last dictionary related word returns the `xt` pointer for a word. This is used to help keep various important bits up to date. ---------------------------------------------------------------------*/ CELL d_xt_for(char *Name, CELL Dictionary) { return memory[d_xt(d_lookup(Dictionary, Name))]; } /*--------------------------------------------------------------------- This interface tracks a few words and variables in the image. These are: Dictionary - the latest dictionary header NotFound - called when a word is not found interpret - the heart of the interpreter/compiler I have to call this periodically, as the Dictionary will change as new words are defined, and the user might write a new error handler or interpreter. ---------------------------------------------------------------------*/ void update_rx() { Dictionary = memory[2]; interpret = d_xt_for("interpret", Dictionary); NotFound = d_xt_for("err:notfound", Dictionary); Compiler = d_xt_for("Compiler", Compiler); } /*=====================================================================*/ /*--------------------------------------------------------------------- Instruction Processor ---------------------------------------------------------------------*/ CELL ngaLoadImage(char *imageFile) { FILE *fp; CELL imageSize; long fileLen; CELL i; if ((fp = fopen(imageFile, "rb")) != NULL) { /* Determine length (in cells) */ fseek(fp, 0, SEEK_END); fileLen = ftell(fp) / sizeof(CELL); if (fileLen > IMAGE_SIZE) { fclose(fp); printf("\nERROR (nga/ngaLoadImage): Image is larger than alloted space!\n"); exit(1); } rewind(fp); /* Read the file into memory */ imageSize = fread(&memory, sizeof(CELL), fileLen, fp); fclose(fp); } else { for (i = 0; i < ngaImageCells; i++) memory[i] = ngaImage[i]; imageSize = i; } return imageSize; } void ngaPrepare() { ip = sp = rp = 0; for (ip = 0; ip < IMAGE_SIZE; ip++) memory[ip] = 0; for (ip = 0; ip < STACK_DEPTH; ip++) data[ip] = 0; for (ip = 0; ip < ADDRESSES; ip++) address[ip] = 0; } void inst_nop() { } void inst_lit() { sp++; ip++; TOS = memory[ip]; } void inst_dup() { sp++; data[sp] = NOS; } void inst_drop() { data[sp] = 0; if (--sp < 0) ip = IMAGE_SIZE; } void inst_swap() { CELL a; a = TOS; TOS = NOS; NOS = a; } void inst_push() { rp++; TORS = TOS; inst_drop(); } void inst_pop() { sp++; TOS = TORS; rp--; } void inst_jump() { ip = TOS - 1; inst_drop(); } void inst_call() { rp++; TORS = ip; ip = TOS - 1; inst_drop(); } void inst_ccall() { CELL a, b; a = TOS; inst_drop(); /* False */ b = TOS; inst_drop(); /* Flag */ if (b != 0) { rp++; TORS = ip; ip = a - 1; } } void inst_return() { ip = TORS; rp--; } void inst_eq() { NOS = (NOS == TOS) ? -1 : 0; inst_drop(); } void inst_neq() { NOS = (NOS != TOS) ? -1 : 0; inst_drop(); } void inst_lt() { NOS = (NOS < TOS) ? -1 : 0; inst_drop(); } void inst_gt() { NOS = (NOS > TOS) ? -1 : 0; inst_drop(); } void inst_fetch() { #ifndef NOCHECKS if (TOS >= IMAGE_SIZE || TOS < -6) { ip = IMAGE_SIZE; printf("\nERROR (nga/inst_fetch): Fetch beyond valid memory range\n"); exit(1); } else { #endif switch (TOS) { case -1: TOS = sp - 1; break; case -2: TOS = rp; break; case -3: TOS = IMAGE_SIZE; break; case -4: TOS = CELL_MIN; break; case -5: TOS = CELL_MAX; break; default: TOS = memory[TOS]; break; } #ifndef NOCHECKS } #endif } void inst_store() { #ifndef NOCHECKS if (TOS <= IMAGE_SIZE && TOS >= 0) { #endif memory[TOS] = NOS; inst_drop(); inst_drop(); #ifndef NOCHECKS } else { ip = IMAGE_SIZE; printf("\nERROR (nga/inst_store): Store beyond valid memory range\n"); exit(1); } #endif } void inst_add() { NOS += TOS; inst_drop(); } void inst_sub() { NOS -= TOS; inst_drop(); } void inst_mul() { NOS *= TOS; inst_drop(); } void inst_divmod() { CELL a, b; a = TOS; b = NOS; #ifndef NOCHECKS if (a == 0) { printf("\nERROR (nga/inst_divmod): Division by zero\n"); exit(1); } #endif TOS = b / a; NOS = b % a; } void inst_and() { NOS = TOS & NOS; inst_drop(); } void inst_or() { NOS = TOS | NOS; inst_drop(); } void inst_xor() { NOS = TOS ^ NOS; inst_drop(); } void inst_shift() { CELL y = TOS; CELL x = NOS; if (TOS < 0) NOS = NOS << (TOS * -1); else { if (x < 0 && y > 0) NOS = x >> y | ~(~0U >> y); else NOS = x >> y; } inst_drop(); } void inst_zret() { if (TOS == 0) { inst_drop(); ip = TORS; rp--; } } void inst_halt() { ip = IMAGE_SIZE; } void inst_ie() { sp++; TOS = NUM_DEVICES; } void inst_iq() { CELL Device = TOS; inst_drop(); IO_queryHandlers[Device](); } void inst_ii() { CELL Device = TOS; inst_drop(); IO_deviceHandlers[Device](); } Handler instructions[] = { inst_nop, inst_lit, inst_dup, inst_drop, inst_swap, inst_push, inst_pop, inst_jump, inst_call, inst_ccall, inst_return, inst_eq, inst_neq, inst_lt, inst_gt, inst_fetch, inst_store, inst_add, inst_sub, inst_mul, inst_divmod, inst_and, inst_or, inst_xor, inst_shift, inst_zret, inst_halt, inst_ie, inst_iq, inst_ii }; void ngaProcessOpcode(CELL opcode) { if (opcode != 0) instructions[opcode](); } int ngaValidatePackedOpcodes(CELL opcode) { CELL raw = opcode; CELL current; int valid = -1; int i; for (i = 0; i < 4; i++) { current = raw & 0xFF; if (!(current >= 0 && current <= 29)) valid = 0; raw = raw >> 8; } return valid; } void ngaProcessPackedOpcodes(CELL opcode) { CELL raw = opcode; int i; for (i = 0; i < 4; i++) { ngaProcessOpcode(raw & 0xFF); raw = raw >> 8; } }