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Merge pull request #932 from ishehadeh/feature/int-to-bytes

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Add int/to-bytes: Serialize int/[su]64 to a buffer
This commit is contained in:
Calvin Rose
2022-03-06 13:11:08 -06:00
committed by GitHub
parent d7ea122cf7 bbb3e16fd1
commit 8045e29a52
2 changed files with 89 additions and 0 deletions
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56
src/core/inttypes.c
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@@ -238,6 +238,61 @@ JANET_CORE_FN(cfun_to_number,
janet_panicf("expected int/u64 or int/s64, got %q", argv[0]);
}
JANET_CORE_FN(cfun_to_bytes,
"(int/to-bytes value &opt endianness buffer)",
"Write the bytes of an `int/s64` or `int/u64` into a buffer.\n"
"The `buffer` parameter specifies an existing buffer to write to, if unset a new buffer will be created.\n"
"Returns the modified buffer.\n"
"The `endianness` paramater indicates the byte order:\n"
"- `nil` (unset): system byte order\n"
"- `:le`: little-endian, least significant byte first\n"
"- `:be`: big-endian, most significant byte first\n") {
janet_arity(argc, 1, 3);
if (janet_is_int(argv[0]) == JANET_INT_NONE) {
janet_panicf("int/to-bytes: expected an int/s64 or int/u64, got %q", argv[0]);
}
int reverse = 0;
if (argc > 1 && !janet_checktype(argv[1], JANET_NIL)) {
JanetKeyword endianness_kw = janet_getkeyword(argv, 1);
if (!janet_cstrcmp(endianness_kw, "le")) {
#if JANET_BIG_ENDIAN
reverse = 1;
#endif
} else if (!janet_cstrcmp(endianness_kw, "be")) {
#if JANET_LITTLE_ENDIAN
reverse = 1;
#endif
} else {
janet_panicf("int/to-bytes: expected endianness :le, :be or nil, got %v", argv[1]);
}
}
JanetBuffer *buffer = NULL;
if (argc > 2 && !janet_checktype(argv[2], JANET_NIL)) {
if (!janet_checktype(argv[2], JANET_BUFFER)) {
janet_panicf("int/to-bytes: expected buffer or nil, got %q", argv[2]);
}
buffer = janet_unwrap_buffer(argv[2]);
janet_buffer_extra(buffer, 8);
} else {
buffer = janet_buffer(8);
}
uint8_t *bytes = janet_unwrap_abstract(argv[0]);
if (reverse) {
for (int i = 0; i < 8; ++i) {
buffer->data[buffer->count + 7 - i] = bytes[i];
}
} else {
memcpy(buffer->data + buffer->count, bytes, 8);
}
buffer->count += 8;
return janet_wrap_buffer(buffer);
}
/*
* Code to support polymorphic comparison.
* int/u64 and int/s64 support a "compare" method that allows
@@ -546,6 +601,7 @@ void janet_lib_inttypes(JanetTable *env) {
JANET_CORE_REG("int/s64", cfun_it_s64_new),
JANET_CORE_REG("int/u64", cfun_it_u64_new),
JANET_CORE_REG("int/to-number", cfun_to_number),
JANET_CORE_REG("int/to-bytes", cfun_to_bytes),
JANET_REG_END
};
janet_core_cfuns_ext(env, NULL, it_cfuns);