Host introspection: Difference between revisions
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(Changed the way to compute the word size using "sizeof(int)".) |
(Added Wren) |
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No match, so big endian. |
No match, so big endian. |
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=={{header|Wren}}== |
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{{trans|C}} |
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As this information cannot be reliably obtained via Wren CLI, we instead embed a Wren script in a C application and ask the host program to get it for us. |
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<lang ecmascript>/* host_introspection.wren */ |
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class C { |
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foreign static wordSize |
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foreign static endianness |
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} |
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System.print("word size = %(C.wordSize) bits") |
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System.print("endianness = %(C.endianness)")</lang> |
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<br> |
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We now embed this Wren script in the following C program, compile and run it. |
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<lang c>#include <stdlib.h> |
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#include <stdio.h> |
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#include <string.h> |
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#include <limits.h> |
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#include "wren.h" |
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void C_wordSize(WrenVM* vm) { |
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/* size_t typically is exactly one word */ |
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int ws = (int)(CHAR_BIT * sizeof(size_t)); |
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/* return result to Wren */ |
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wrenSetSlotDouble(vm, 0, (double)ws); |
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} |
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void C_endianness(WrenVM* vm) { |
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/* Check if the least significant bit is located in the lowest-address byte. */ |
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int one = 1; |
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char *e = (*(char *)&one) ? "little" : "big"; |
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/* return result to Wren */ |
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wrenSetSlotString(vm, 0, e); |
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} |
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WrenForeignMethodFn bindForeignMethod( |
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WrenVM* vm, |
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const char* module, |
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const char* className, |
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bool isStatic, |
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const char* signature) { |
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if (strcmp(module, "main") == 0) { |
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if (strcmp(className, "C") == 0) { |
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if (isStatic && strcmp(signature, "wordSize") == 0) { |
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return C_wordSize; |
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} else if (isStatic && strcmp(signature, "endianness") == 0) { |
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return C_endianness; |
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} |
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} |
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} |
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return NULL; |
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} |
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static void writeFn(WrenVM* vm, const char* text) { |
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printf("%s", text); |
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} |
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void errorFn(WrenVM* vm, WrenErrorType errorType, const char* module, const int line, const char* msg) { |
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switch (errorType) { |
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case WREN_ERROR_COMPILE: |
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printf("[%s line %d] [Error] %s\n", module, line, msg); |
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break; |
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case WREN_ERROR_STACK_TRACE: |
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printf("[%s line %d] in %s\n", module, line, msg); |
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break; |
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case WREN_ERROR_RUNTIME: |
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printf("[Runtime Error] %s\n", msg); |
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break; |
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} |
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} |
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char *readFile(const char *fileName) { |
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FILE *f = fopen(fileName, "r"); |
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fseek(f, 0, SEEK_END); |
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long fsize = ftell(f); |
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rewind(f); |
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char *script = malloc(fsize + 1); |
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fread(script, 1, fsize, f); |
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fclose(f); |
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script[fsize] = 0; |
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return script; |
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} |
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int main() { |
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WrenConfiguration config; |
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wrenInitConfiguration(&config); |
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config.writeFn = &writeFn; |
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config.errorFn = &errorFn; |
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config.bindForeignMethodFn = &bindForeignMethod; |
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WrenVM* vm = wrenNewVM(&config); |
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const char* module = "main"; |
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const char* fileName = "host_introspection.wren"; |
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char *script = readFile(fileName); |
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WrenInterpretResult result = wrenInterpret(vm, module, script); |
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switch (result) { |
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case WREN_RESULT_COMPILE_ERROR: |
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printf("Compile Error!\n"); |
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break; |
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case WREN_RESULT_RUNTIME_ERROR: |
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printf("Runtime Error!\n"); |
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break; |
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case WREN_RESULT_SUCCESS: |
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break; |
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} |
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wrenFreeVM(vm); |
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free(script); |
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return 0; |
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}</lang> |
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{{out}} |
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The results, as expected, for my x64 Ubuntu 20.04 system are: |
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<pre> |
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word size = 64 bits |
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endianness = little |
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</pre> |
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=={{header|XPL0}}== |
=={{header|XPL0}}== |