gecode.c

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/*
 * gecode.c - GE 100-series internal graphic character code.
 *
 * GE 100 Series Graphic Character Set — machine byte -> glyph, transcribed from
 * the GE APS Reference Manual (EDV-AFL vol. 03) Figure 3, p.16. The 64-character
 * graphic set occupies 0x40-0x5F and 0xA0-0xBF; all other codes are non-graphic.
 * Used to annotate DB data bytes (gdis) and to render printer/typewriter output
 * with the character it represents ON THE MACHINE (not ASCII — which did not yet
 * exist). Glyphs that have no ASCII equivalent (up/left arrows 0xA0/0xBA, long
 * dash 0xAA, bullet 0xAC) render '.'.
 *
 * This table is corroborated by the CRZ card transcoder: CRZ[2] §5.3 "Table 3 —
 * IBM card code and Internal GECB code equivalent" (vol. [2] p.113) shows the
 * transcoder converts card punches to this same internal code (digit '0'=0x40,
 * 'J'=0xA1). The EBCDIC-like codes in transcode.c (digits 0xF0-0xF9) are an
 * artifact of the externally-supplied funktionalcpu.bin, not the machine's
 * code — see docs/ISA.md §2.1 for the full reconciliation.
 */
 
#include "gecode.h"
 
static const char GE_GLYPH[256] = {
    [0x40]='0',[0x41]='1',[0x42]='2',[0x43]='3',[0x44]='4',[0x45]='5',
    [0x46]='6',[0x47]='7',[0x48]='8',[0x49]='9',
    [0x4A]='[',[0x4B]='#',[0x4C]='@',[0x4D]=':',[0x4E]='>',[0x4F]='?',
    [0x50]=' ',[0x51]='A',[0x52]='B',[0x53]='C',[0x54]='D',[0x55]='E',
    [0x56]='F',[0x57]='G',[0x58]='H',[0x59]='I',
    [0x5A]='&',[0x5B]='.',[0x5C]=']',[0x5D]='(',[0x5E]='<',[0x5F]='\\',
    [0xA1]='J',[0xA2]='K',[0xA3]='L',[0xA4]='M',[0xA5]='N',[0xA6]='O',
    [0xA7]='P',[0xA8]='Q',[0xA9]='R',
    [0xAB]='$',[0xAD]=')',[0xAE]=';',[0xAF]='\'',
    [0xB0]='+',[0xB1]='/',[0xB2]='S',[0xB3]='T',[0xB4]='U',[0xB5]='V',
    [0xB6]='W',[0xB7]='X',[0xB8]='Y',[0xB9]='Z',
    [0xBB]=',',[0xBC]='%',[0xBD]='=',[0xBE]='"',[0xBF]='!',
};
 
char ge_glyph(uint8_t b)
{
    if (b == 0x00)
        return '\n';
    if (b == 0xAA)
        return '-';
    char c = GE_GLYPH[b];
    return c ? c : '.';
}
 
uint8_t ge_code(uint8_t c)
{
    if (c >= '0' && c <= '9') return 0x40 + (c - '0');
    if (c >= 'A' && c <= 'I') return 0x51 + (c - 'A');
    if (c >= 'J' && c <= 'R') return 0xA1 + (c - 'J');
    if (c >= 'S' && c <= 'Z') return 0xB2 + (c - 'S');
    if (c >= 'a' && c <= 'z') return ge_code((uint8_t)(c - 'a' + 'A'));
    switch (c) {
    case '\n': return 0x00;
    case '\r': return 0x00;
    case '\t': return 0x50;
    case ' ':  return 0x50;
    case '[':  return 0x4A;
    case '#':  return 0x4B;
    case '@':  return 0x4C;
    case ':':  return 0x4D;
    case '>':  return 0x4E;
    case '?':  return 0x4F;
    case '&':  return 0x5A;
    case '.':  return 0x5B;
    case ']':  return 0x5C;
    case '(':  return 0x5D;
    case '<':  return 0x5E;
    case '\\': return 0x5F;
    case '$':  return 0xAB;
    case '-':  return 0xAA;
    case ')':  return 0xAD;
    case ';':  return 0xAE;
    case '\'': return 0xAF;
    case '+':  return 0xB0;
    case '/':  return 0xB1;
    case ',':  return 0xBB;
    case '%':  return 0xBC;
    case '=':  return 0xBD;
    case '"':  return 0xBE;
    case '!':  return 0xBF;
    case 0:    return 0x00;
    }
    return 0x50;
}