80 lines
2.8 KiB
ReStructuredText
80 lines
2.8 KiB
ReStructuredText
Write You a Forth, 0x03
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-----------------------
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:date: 2018-03-09 13:10
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:tags: wyaf, forth
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So the last post had some issues and I hadn't updated the front end to use the
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new tooling. I removed the arena and switched to the internal dictionary::
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#include "defs.h"
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#include "eval.h"
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#include "stack.h"
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#include "word.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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void
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hello(void)
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{
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printf("hello, world\n");
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}
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int
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main(void)
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{
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dstack_push(2);
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dstack_push(3);
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append_native_word("hello", 5, hello);
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uintptr_t hwb = 0;
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if (!lookup("hello", 5, &hwb)) {
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fprintf(stderr, "failed to lookup 'hello'\n");
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exit(1);
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}
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printf("hello: 0x%lx\n", (unsigned long)hwb);
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if (!execute("hello", 5)) {
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fprintf(stderr, "failed to execute 'hello'\n");
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exit(1);
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}
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printf("finished\n");
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}
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Also, there's a (not-so) subtle bug in ``word.c``: the header is overwritten by the function
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body, which is the path to segfaulting. I've also added an offset variable to make tracking
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the offset easier::
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void
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store_native(uint8_t *entry, const char *name, const uint8_t len, void(*target)(void))
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{
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uintptr_t target_p = (uintptr_t)target;
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- size_t link = 2 + len + (2 * sizeof(uintptr_t));
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+ size_t offset = 2 + len + sizeof(size_t);
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+ size_t link = offset + (2 * sizeof(uintptr_t));
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/* write the header */
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entry[0] = len;
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@@ -45,8 +66,9 @@ store_native(uint8_t *entry, const char *name, const uint8_t len, void(*target)(
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memcpy(entry+2+len, &link, sizeof(link));
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/* write the native executor codeword and the function pointer */
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- memcpy(entry, (uint8_t *)(&nexec_p), sizeof(uintptr_t));
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- memcpy(entry + sizeof(uintptr_t), (uint8_t *)(&target_p), sizeof(uintptr_t));
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+ memcpy(entry+offset, (uint8_t *)(&nexec_p), sizeof(uintptr_t));
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+ offset += sizeof(uintptr_t);
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+ memcpy(entry+offset, (uint8_t *)(&target_p), sizeof(uintptr_t));
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}
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The header file ``word.h`` didn't contain ``append_native_word``, ``lookup``,
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or ``execute``, so that gets updated too. The end result is::
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$ ./kf-default
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hello: 0x6cbc6f
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hello, world
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finished
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As usual, the code is tagged with `part-0x09 <https://github.com/kisom/kforth/tree/part-0x09>`_. |