diff options
| -rw-r--r-- | bin/bit.y | 32 | ||||
| -rw-r--r-- | bin/man1/bit.1 | 12 |
2 files changed, 28 insertions, 16 deletions
diff --git a/bin/bit.y b/bin/bit.y index b9e39c32..99199a3d 100644 --- a/bin/bit.y +++ b/bin/bit.y @@ -27,18 +27,16 @@ #define MASK(b) ((1ULL << (b)) - 1) -#define YYSTYPE uint64_t - -static void yyerror(const char *str) { - warnx("%s", str); -} - +static void yyerror(const char *str); static int yylex(void); -static uint64_t result; +#define YYSTYPE uint64_t + +static uint64_t vars[128]; %} +%right '=' %left '|' %left '^' %left '&' @@ -48,17 +46,17 @@ static uint64_t result; %right '~' %left 'K' 'M' 'G' 'T' -%token Int +%token Int Var %% -start: - expr { result = $1; } +stmt: + expr { vars['_'] = $1; } ; expr: Int - | '_' { $$ = result; } + | Var { $$ = vars[$1]; } | '(' expr ')' { $$ = $2; } | expr 'K' { $$ = $1 << 10; } | expr 'M' { $$ = $1 << 20; } @@ -77,10 +75,15 @@ expr: | expr '&' expr { $$ = $1 & $3; } | expr '^' expr { $$ = $1 ^ $3; } | expr '|' expr { $$ = $1 | $3; } + | Var '=' expr { $$ = vars[$1] = $3; } ; %% +static void yyerror(const char *str) { + warnx("%s", str); +} + #define T(a, b) ((int)(a) << 8 | (int)(b)) static const char *input; @@ -130,6 +133,11 @@ static int yylex(void) { } else if (isdigit(input[0])) { return lexInt(10); } + + if (input[0] == '_' || islower(input[0])) { + yylval = *input++; + return Var; + } switch (T(input[0], input[1])) { case T('<', '<'): input += 2; return Shl; @@ -166,6 +174,8 @@ int main(void) { int error = yyparse(); if (error) continue; + uint64_t result = vars['_']; + int bits = result > UINT32_MAX ? 64 : result > UINT16_MAX ? 32 : result > UINT8_MAX ? 16 diff --git a/bin/man1/bit.1 b/bin/man1/bit.1 index ddb26535..b61bc704 100644 --- a/bin/man1/bit.1 +++ b/bin/man1/bit.1 @@ -1,4 +1,4 @@ -.Dd May 12, 2019 +.Dd June 7, 2019 .Dt BIT 1 .Os . @@ -12,8 +12,8 @@ .Sh DESCRIPTION .Nm is an integer calculator. -Its syntax resembles that of C, -with the following additions: +Its syntax resembles that of C expressions, +with the following changes: . .Bl -bullet .It @@ -34,9 +34,11 @@ The postfix operators .Sy T are used as constant multipliers. .It -The symbol +Single-letter (lower case) variables +can be assigned. +The variable .Sy _ -is used to refer to the previous result. +stores the previous result. .El . .Sh SEE ALSO |