diff options
Diffstat (limited to 'appl/lib/convcs/euc-jp_btos.b')
| -rw-r--r-- | appl/lib/convcs/euc-jp_btos.b | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/appl/lib/convcs/euc-jp_btos.b b/appl/lib/convcs/euc-jp_btos.b new file mode 100644 index 00000000..5a5aa9ec --- /dev/null +++ b/appl/lib/convcs/euc-jp_btos.b @@ -0,0 +1,162 @@ +implement Btos; + +# EUC-JP is based on ISO2022 but only uses the 8 bit stateless encoding. +# Thus, only the following ISO2022 shift functions are used: +# SINGLE-SHIFT TWO +# SINGLE-SHIFT THREE +# +# The initial state is G0 mapped into GL and G1 mapped into GR +# SINGLE-SHIFT TWO maps G2 into GR for one code-point encoding +# SINGLE-SHIFT THREE maps G3 into GR for one code-point encoding +# +# EUC-JP has pre-assigned code elements (G0..G3) that are never re-assigned +# by means on ISO2022 code-identification functions (escape sequences) +# +# G0 = ASCII +# G1 = JIS X 0208 +# G2 = JIS X 0201 Kana +# G3 = JIS X 0212 + +include "sys.m"; +include "convcs.m"; + +sys : Sys; + +SS2 : con 16r8E; # ISO2022 SINGLE-SHIFT TWO +SS3 : con 16r8F; # ISO2022 SINGLE-SHIFT THREE + +MAXINT : con 16r7fffffff; +BADCHAR : con 16rFFFD; + +G1PATH : con "/lib/convcs/jisx0208-1997"; +G2PATH : con "/lib/convcs/jisx0201kana"; +G3PATH : con "/lib/convcs/jisx0212"; + +g1map : string; +g2map : string; +g3map : string; + +G1PAGESZ : con 94; +G1NPAGES : con 84; +G1PAGE0 : con 16rA1; +G1CHAR0 : con 16rA1; + +G2PAGESZ : con 63; +G2NPAGES : con 1; +G2CHAR0 : con 16rA1; + +G3PAGESZ : con 94; +G3NPAGES : con 77; +G3PAGE0 : con 16rA1; +G3CHAR0 : con 16rA1; + +init(nil : string) : string +{ + sys = load Sys Sys->PATH; + + error := ""; + (error, g1map) = getmap(G1PATH, G1PAGESZ, G1NPAGES); + if (error != nil) + return error; + (error, g2map) = getmap(G2PATH, G2PAGESZ, G2NPAGES); + if (error != nil) + return error; + (error, g3map) = getmap(G3PATH, G3PAGESZ, G3NPAGES); + return error; +} + +getmap(path : string, pgsz, npgs : int) : (string, string) +{ + fd := sys->open(path, Sys->OREAD); + if (fd == nil) + return (sys->sprint("%s: %r", path), nil); + + buf := array[(pgsz * npgs) * Sys->UTFmax] of byte; + nread := 0; + for (;nread < len buf;) { + n := sys->read(fd, buf[nread:], Sys->ATOMICIO); + if (n <= 0) + break; + nread += n; + } + map := string buf[:nread]; + if (len map != (pgsz * npgs)) + return (sys->sprint("%s: bad data", path), nil); + return (nil, map); +} + +btos(nil : Convcs->State, b : array of byte, n : int) : (Convcs->State, string, int) +{ + nbytes := 0; + str := ""; + + if (n == -1) + n = MAXINT; + + codelen := 1; + codeix := 0; + G0, G1, G2, G3 : con iota; + state := G0; + bytes := array [3] of int; + + while (len str < n) { + for (i := nbytes + codeix; i < len b && codeix < codelen; i++) + bytes[codeix++]= int b[i]; + + if (codeix != codelen) + break; + + case state { + G0 => + case bytes[0] { + 0 to 16r7f => + str[len str] = bytes[0]; + G1PAGE0 to G1PAGE0+G1NPAGES => + state = G1; + codelen = 2; + continue; + SS2 => + state = G2; + codelen = 2; + continue; + SS3 => + state = G3; + codelen = 3; + continue; + * => + str[len str] = BADCHAR; + } + G1 => + # double byte encoding + page := bytes[0] - G1PAGE0; + char := bytes[1] - G1CHAR0; + str[len str] = g1map[(page * G1PAGESZ) + char]; + G2 => + # single byte encoding (byte 0 == SS2) + char := bytes[1] - G2CHAR0; + if (char < 0 || char >= len g2map) + char = BADCHAR; + else + char = g2map[char]; + str[len str] = char; + G3 => + # double byte encoding (byte 0 == SS3) + page := bytes[1] - G3PAGE0; + char := bytes[2] - G3CHAR0; + if (page < 0 || page >= G3NPAGES) { + # first byte is wrong - backup + i--; + str[len str] = BADCHAR; + } else if (char >= G3PAGESZ) + str[len str] = BADCHAR; + else + str[len str] = g3map[(page * G3PAGESZ)+char]; + } + + state = G0; + nbytes = i; + codelen = 1; + codeix = 0; + } + return (nil, str, nbytes); +}
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