4-variable-simplifier/evaluate.c

500 lines
13 KiB
C

#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <defines.h>
#include "evaluate.h"
uint16_t evaluate(const char* text)
{
enum {
tk_uninitialized,
tk_0,
tk_1,
tk_w,
tk_x,
tk_y,
tk_z,
tk_oparen,
tk_cparen,
tk_emark,
tk_emarkequals,
tk_emarkvbar,
tk_emarkampersand,
tk_equalsequals,
tk_vbarvbar,
tk_vbaremark,
tk_qmark,
tk_less_than,
tk_less_than_eq,
tk_greater_than,
tk_greater_than_eq,
tk_ampersandemark,
tk_ampersandampersand,
tk_colon,
tk_EOF,
} tokenkind = tk_uninitialized;
const char* moving = text;
void next_token(void)
{
while (*moving && *moving == ' ')
moving++;
switch (*moving)
{
case 0:
tokenkind = tk_EOF;
break;
case '0':
tokenkind = tk_0, moving++;
break;
case '1':
tokenkind = tk_1, moving++;
break;
case 'w':
tokenkind = tk_w, moving++;
break;
case 'x':
tokenkind = tk_x, moving++;
break;
case 'y':
tokenkind = tk_y, moving++;
break;
case 'z':
tokenkind = tk_z, moving++;
break;
case '(':
tokenkind = tk_oparen, moving++;
break;
case ')':
tokenkind = tk_cparen, moving++;
break;
case '?':
tokenkind = tk_qmark, moving++;
break;
case ':':
tokenkind = tk_colon, moving++;
break;
// either '||' or '|!':
case '|':
{
moving++;
switch (*moving)
{
case '|':
tokenkind = tk_vbarvbar, moving++;
break;
case '!':
tokenkind = tk_vbaremark, moving++;
break;
default:
{
puts("syntax error");
exit(1);
break;
}
}
break;
}
// either '&&' or '&!':
case '&':
{
moving++;
switch (*moving)
{
case '&':
tokenkind = tk_ampersandampersand, moving++;
break;
case '!':
tokenkind = tk_ampersandemark, moving++;
break;
default:
{
puts("syntax error");
exit(1);
break;
}
}
break;
}
// either '!' or '!=' or '!&' or '!|'
case '!':
{
moving++;
switch (*moving)
{
case '=':
tokenkind = tk_emarkequals, moving++;
break;
case '|':
tokenkind = tk_emarkvbar, moving++;
break;
case '&':
tokenkind = tk_emarkampersand, moving++;
break;
default:
tokenkind = tk_emark;
break;
}
break;
}
case '<':
{
moving++;
switch (*moving)
{
case '=':
tokenkind = tk_less_than_eq, moving++;
break;
default:
{
tokenkind = tk_less_than;
break;
}
}
break;
}
case '>':
{
moving++;
switch (*moving)
{
case '=':
tokenkind = tk_greater_than_eq, moving++;
break;
default:
{
tokenkind = tk_greater_than;
break;
}
}
break;
}
// could only be '==':
case '=':
{
moving++;
switch (*moving)
{
case '=':
tokenkind = tk_equalsequals, moving++;
break;
default:
{
puts("syntax error");
exit(1);
break;
}
}
break;
}
default:
assert(!"TODO");
break;
}
}
next_token();
uint16_t parse_root(void)
{
uint16_t parse_ternary(void)
{
uint16_t parse_ors(void)
{
uint16_t parse_ands(void)
{
uint16_t parse_equals(void)
{
uint16_t parse_compares(void)
{
uint16_t parse_prefix(void)
{
uint16_t parse_primary(void)
{
uint16_t retval;
switch (tokenkind)
{
case tk_0:
retval = 0, next_token();
break;
case tk_1:
retval = M, next_token();
break;
case tk_w:
retval = W, next_token();
break;
case tk_x:
retval = X, next_token();
break;
case tk_y:
retval = Y, next_token();
break;
case tk_z:
retval = Z, next_token();
break;
case tk_oparen:
{
next_token();
retval = parse_root();
if (tokenkind != tk_cparen)
{
assert(!"NOPE");
}
next_token();
break;
}
default:
assert(!"TODO");
break;
}
return retval;
}
if (tokenkind == tk_emark)
{
next_token();
return ~parse_prefix();
}
else
{
return parse_primary();
}
}
uint16_t left = parse_prefix();
again: switch (tokenkind)
{
case tk_less_than:
{
next_token();
left = (~left & parse_equals()) & M;
goto again;
}
case tk_less_than_eq:
{
next_token();
left = (~left | parse_equals()) & M;
goto again;
}
case tk_greater_than_eq:
{
next_token();
left = ( left | ~parse_equals()) & M;
goto again;
}
case tk_greater_than:
{
next_token();
left = ( left & ~parse_equals()) & M;
goto again;
}
default:
break;
}
return left;
}
uint16_t left = parse_compares();
again: switch (tokenkind)
{
case tk_equalsequals:
{
next_token();
left = ~(left ^ parse_equals()) & M;
goto again;
}
case tk_emarkequals:
{
next_token();
left = left ^ parse_equals();
goto again;
}
default:
break;
}
return left;
}
uint16_t left = parse_equals();
again: switch (tokenkind)
{
case tk_ampersandampersand:
{
next_token();
left = left & parse_equals();
goto again;
}
case tk_ampersandemark:
{
next_token();
left = ~left & parse_equals();
goto again;
}
case tk_emarkampersand:
{
next_token();
left = ~(left & parse_equals());
goto again;
}
default:
break;
}
return left;
}
uint16_t left = parse_ands();
again: switch (tokenkind)
{
case tk_vbarvbar:
{
next_token();
left = left | parse_ands();
goto again;
}
case tk_vbaremark:
{
next_token();
left = (~left | parse_ands()) & M;
goto again;
}
case tk_emarkvbar:
{
next_token();
left = ~(left | parse_ands()) & M;
goto again;
}
default:
break;
}
return left;
}
uint16_t cond = parse_ors();
if (tokenkind == tk_qmark)
{
next_token();
uint16_t left = parse_ors();
if (tokenkind != tk_colon)
{
puts("syntax error!");
exit(1);
}
next_token();
uint16_t right = parse_ternary();
return (cond & left) | (~cond & right);
}
else
{
return cond;
}
}
return parse_ternary();
}
uint16_t truthtable = parse_root();
if (tokenkind != tk_EOF)
{
puts("syntax error!");
exit(1);
}
return truthtable;
}