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Code Issues 1 Releases Wiki Activity

int/to-bytes: return a buffer instead of a tuple

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Buffers make more sense for this function because one of their primary
use cases is working with bytes.
The tuple implementation was an array of floats,  which is less
performant and ergonomic for common operations. (i.e: bit manipulation)

Buffers also have the advantage they are mutable, meaning the user
can write ints to an existing buffer.
This commit is contained in:
Ian Shehadeh
2022-03-05 08:21:53 -05:00
parent 6aea7c7f70
commit bbb3e16fd1
2 changed files with 47 additions and 17 deletions
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36
src/core/inttypes.c
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@@ -239,13 +239,15 @@ JANET_CORE_FN(cfun_to_number,
}
JANET_CORE_FN(cfun_to_bytes,
"(int/to-bytes value &opt endianness)",
"Convert an `int/s64` or `int/u64` into an 8-element tuple of bytes.\n"
"the endianness paramater indicates the byte order:\n"
"(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, 2);
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]);
}
@@ -266,13 +268,29 @@ JANET_CORE_FN(cfun_to_bytes,
}
}
uint8_t *bytes = janet_unwrap_abstract(argv[0]);
Janet *bytes_tuple = janet_tuple_begin(8);
for (int i = 0; i < 8; ++i) {
bytes_tuple[i] = janet_wrap_integer(bytes[reverse ? 7 - i : i]);
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);
}
return janet_wrap_tuple(janet_tuple_end(bytes_tuple));
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);
}
/*