diff options
| -rw-r--r-- | buf.c | 34 | ||||
| -rw-r--r-- | buf.h | 1 | ||||
| -rw-r--r-- | tests/012/buf.tl | 16 | ||||
| -rw-r--r-- | txr.1 | 22 |
4 files changed, 73 insertions, 0 deletions
@@ -1675,6 +1675,39 @@ val buf_trunc(val buf, val bits) } } +val buf_bitset(val buf) +{ + val self = lit("buf-bitset"); + struct buf *b = buf_handle(buf, self); + ucnum l = c_unum(b->len, self), i, j; + list_collect_decl (out, ptail); + + for (i = l - 1, j = 0; i != convert(ucnum, -1); --i, j++) { + unsigned byte = b->data[i]; + if (byte) { + val bitpos = mul(unum(j), num_fast(8)); + if (byte & 1) + ptail = list_collect(ptail, bitpos); + if (byte & 2) + ptail = list_collect(ptail, succ(bitpos)); + if (byte & 4) + ptail = list_collect(ptail, ssucc(bitpos)); + if (byte & 8) + ptail = list_collect(ptail, sssucc(bitpos)); + if (byte & 16) + ptail = list_collect(ptail, plus(bitpos, num_fast(4))); + if (byte & 32) + ptail = list_collect(ptail, plus(bitpos, num_fast(5))); + if (byte & 64) + ptail = list_collect(ptail, plus(bitpos, num_fast(6))); + if (byte & 128) + ptail = list_collect(ptail, plus(bitpos, num_fast(7))); + } + } + + return out; +} + void buf_init(void) { reg_fun(intern(lit("make-buf"), user_package), func_n3o(make_buf, 1)); @@ -1775,6 +1808,7 @@ void buf_init(void) reg_fun(intern(lit("buf-xor"), user_package), func_n2(buf_xor)); reg_fun(intern(lit("buf-not"), user_package), func_n1(buf_not)); reg_fun(intern(lit("buf-trunc"), user_package), func_n2(buf_trunc)); + reg_fun(intern(lit("buf-bitset"), user_package), func_n1(buf_bitset)); fill_stream_ops(&buf_strm_ops); } @@ -131,5 +131,6 @@ val buf_or(val bufa, val bufb); val buf_xor(val bufa, val bufb); val buf_not(val buf); val buf_trunc(val buf, val bits); +val buf_bitset(val buf); void buf_init(void); diff --git a/tests/012/buf.tl b/tests/012/buf.tl index 20f9d8d6..6e7a3159 100644 --- a/tests/012/buf.tl +++ b/tests/012/buf.tl @@ -300,3 +300,19 @@ (buf-trunc #b'ff' 17) #b'0000ff' (buf-trunc #b'aabbccdd' 24) #b'bbccdd' (buf-trunc #b'aabbccdd' 20) #b'0bccdd') + +(mtest + (buf-bitset #b'') () + (buf-bitset #b'00') () + (buf-bitset #b'01') (0) + (buf-bitset #b'02') (1) + (buf-bitset #b'04') (2) + (buf-bitset #b'08') (3) + (buf-bitset #b'10') (4) + (buf-bitset #b'20') (5) + (buf-bitset #b'40') (6) + (buf-bitset #b'80') (7) + (buf-bitset #b'ff') (0 1 2 3 4 5 6 7) + (buf-bitset #b'ff00') (8 9 10 11 12 13 14 15) + (buf-bitset #b'03ff') (0 1 2 3 4 5 6 7 8 9) + (buf-bitset (buf-ash #b'03ff' 100)) (100 101 102 103 104 105 106 107 108 109)) @@ -30402,6 +30402,28 @@ buffer is masked so that any bits which lie outside of the truncation are zero. (buf-trunc #b'ff' 0) -> #b'' .brev +.coNP Function @ buf-bitset +.synb +.mets (buf-bitset << buf ) +.syne +.desc +The +.code buf-bitset +function returns the positions all of bits within buffer +.meta buf +which are set (have a value of 1). The values appear in +increasing order (right to left bit positions). +Bit zero is the least significant bit of the last byte +of the buffer. + +.TP* Examples: + +.verb + (buf-bitset #b'') -> nil + (buf-bitset #b'01') -> (0) + (buf-bitset #b'03fe') -> (1 2 3 4 5 6 7 8 9) +.brev + .coNP Functions @ buf-compress and @ buf-decompress .synb .mets (buf-compress < buf <> [ level ]) |