ref: 57446af9a447c3a81414131f2407a9ca6f6a1a94
dir: /appl/lib/convcs/euc-jp_btos.b/
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); }