diff options
| -rw-r--r-- | buf.c | 52 | ||||
| -rw-r--r-- | buf.h | 2 | ||||
| -rw-r--r-- | tests/012/buf.tl | 27 | ||||
| -rw-r--r-- | txr.1 | 85 |
4 files changed, 166 insertions, 0 deletions
@@ -1625,6 +1625,56 @@ val buf_xor(val bufa, val bufb) } } +val buf_not(val buf) +{ + val self = lit("buf-not"); + struct buf *b = buf_handle(buf, self); + ucnum l = c_unum(b->len, self); + + if (l == 0) { + return buf; + } else if (l == convert(ucnum, -1)) { + uw_throwf(error_s, lit("~a: array size overflow"), self, nao); + } else { + val obuf = make_ubuf(l); + struct buf *ob = buf_handle(obuf, self); + ucnum i; + + for (i = 0; i < l; i++) + ob->data[i] = b->data[i] ^ 0xff; + + return obuf; + } +} + +val buf_trunc(val buf, val bits) +{ + val self = lit("buf-not"); + cnum b = c_num(bits, self); + struct buf *bh = buf_handle(buf, self); + ucnum l = c_unum(bh->len, self); + + if (b <= 0) { + return make_buf(zero, nil, zero); + } else { + ucnum bytes = (b + 7) / 8; + val obuf = make_ubuf(bytes); + struct buf *ob = buf_handle(obuf, self); + + if (bytes > l) { + memcpy(ob->data + bytes - l, bh->data, l); + memset(ob->data, 0, bytes - l); + } else { + memcpy(ob->data, bh->data + l - bytes, bytes); + } + + if (b % 8 != 0) + ob->data[0] &= (0xffu >> (8 - b % 8)); + + return obuf; + } +} + void buf_init(void) { reg_fun(intern(lit("make-buf"), user_package), func_n3o(make_buf, 1)); @@ -1723,6 +1773,8 @@ void buf_init(void) reg_fun(intern(lit("buf-and"), user_package), func_n2(buf_and)); reg_fun(intern(lit("buf-or"), user_package), func_n2(buf_or)); 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)); fill_stream_ops(&buf_strm_ops); } @@ -129,5 +129,7 @@ val buf_fash(val buf, val bits); val buf_and(val bufa, val bufb); 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); void buf_init(void); diff --git a/tests/012/buf.tl b/tests/012/buf.tl index f6c35ac7..20f9d8d6 100644 --- a/tests/012/buf.tl +++ b/tests/012/buf.tl @@ -273,3 +273,30 @@ (buf-xor #b'aa' #b'ffff') #b'ff55' (buf-xor #b'ff' #b'ffaa') #b'ff55' (buf-xor #b'ff00ff0f' #b'1baddeadbeef') #b'1bad21ad41e0') + +(mtest + (buf-not #b'') #b'' + (buf-not #b'00') #b'ff' + (buf-not #b'aa') #b'55' + (buf-not #b'aa55') #b'55aa' + (buf-not #b'ff00ff00ff00') #b'00ff00ff00ff') + +(mtest + (buf-trunc #b'' -1) #b'' + (buf-trunc #b'' -0) #b'' + (buf-trunc #b'' -1) #b'' + (buf-trunc #b'' -1000) #b'' + (buf-trunc #b'ff' 8) #b'ff' + (buf-trunc #b'ff' 7) #b'7f' + (buf-trunc #b'ff' 6) #b'3f' + (buf-trunc #b'ff' 5) #b'1f' + (buf-trunc #b'ff' 4) #b'0f' + (buf-trunc #b'ff' 3) #b'07' + (buf-trunc #b'ff' 2) #b'03' + (buf-trunc #b'ff' 1) #b'01' + (buf-trunc #b'ff' 0) #b'' + (buf-trunc #b'ff' 9) #b'00ff' + (buf-trunc #b'ff' 16) #b'00ff' + (buf-trunc #b'ff' 17) #b'0000ff' + (buf-trunc #b'aabbccdd' 24) #b'bbccdd' + (buf-trunc #b'aabbccdd' 20) #b'0bccdd') @@ -30316,6 +30316,91 @@ and .code buf-xor calculates the bitwise Boolean exclusive "or". +.coNP Function @ buf-not +.synb +.mets (buf-not << buf ) +.syne +.desc +The +.code buf-not +function returns the bitwise complement of +.codn buf . + +If +.meta buf +is empty, then an empty buffer is returned which may be +.meta buf +itself. + +Otherwise, a new buffer is returned of the same length as +.meta buf +whose bytes are the bitwise complements of corresponding bytes in +.metn buf . + +Complement means that wherever +.meta buf +has a bit whose value is 1, the corresponding bit in the same position +of the returned buffer has a zero, and vice versa. + +.TP* Examples: + +.verb + (buf-not #b'') -> #b'' + (buf-not #b'fe') -> #b'01 + (buf-not #b'aa55') -> #b'55aa' + (buf-not #b'00008000') -> #b'ffff7fff' +.brev + +.coNP Function @ buf-trunc +.synb +.mets (buf-trunc < buf << bits ) +.syne +.desc +The +.code buf-trunc +function calculates a buffer by either truncating or extending +.meta buf +to the specified number of bits. + +If +.meta bits +is zero or less, then an empty buffer is returned; if +.meta buf +is also empty then the returned buffer may be +.meta buf +itself. + +Truncation or extension takes place the left side of the +buffer value. If both the input and output buffer are non-empty +(have at least one byte), then their rightmost bytes correspond. + +Because buffers are composed of a whole number of bytes, the +.code buf-trunc +cannot produce a buffer which is exactly +.meta bits +wide when +.meta bits +is not divisible by 8. In this situation, +.meta bits +is rounded up to a value divisible by 8, which is used to determine the +adjusted length of the returned buffer. The leftmost byte of the returned +buffer is masked so that any bits which lie outside of the truncation are zero. + +.TP* Examples: + +.verb + (buf-trunc #b'' 0) -> #b'' + (buf-trunc #b'' 16) -> #b'0000' + (buf-trunc #b'' 17) -> #b'000000' + (buf-trunc #b'ffff' 17) -> #b'00ffff' + (buf-trunc #b'ffff' 14) -> #b'3fff' + (buf-trunc #b'ffff' 12) -> #b'0fff' + (buf-trunc #b'ff' 8) -> #b'ff' + (buf-trunc #b'ff' 7) -> #b'7f' + (buf-trunc #b'ff' 2) -> #b'03' + (buf-trunc #b'ff' 1) -> #b'01' + (buf-trunc #b'ff' 0) -> #b'' +.brev .coNP Functions @ buf-compress and @ buf-decompress .synb |