Mercurial > hg > index.cgi
diff src/expr.s @ 80:bb50ac9fdf37
Checkpoint with very basic integer and floating point arithmetic, untested
This commit has implementations for floating point add, subtract, multiply,
and divide, along with 32 bit signed integer equivalents. These can probably
be optimized and they are untested.
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Sat, 07 Oct 2023 02:56:59 -0600 |
| parents | ba559f231929 |
| children | f959c92bc329 |
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--- a/src/expr.s Sun Sep 10 23:18:17 2023 -0600 +++ b/src/expr.s Sat Oct 07 02:56:59 2023 -0600 @@ -88,8 +88,10 @@ ; 15. Read a character and go to step 7 ; ; If the result ends up being larger than a floating point value can hold, return Overflow -eval_number ldb #valtype_int ; flag result as an integer - stb val0_val.type +eval_number + if 0 + ldb #valtype_int ; flag result as an integer + stb val0+val.type ldx zero ; blank out the value except type stx val0 stx val0+2 @@ -101,7 +103,7 @@ beq eval_number3 ; brif so cmpa #tok_minus ; negative (operator negative)? bne eval_number2 ; brif not -eval_number3 com val0+val.fpsign ; invert sign (multiple negatives will flip this multiple times) +eval_number3 com val0+val.fpssign ; invert sign (multiple negatives will flip this multiple times) bra eval_number0 ; deal with next input eval_number2 cmpa #'+ ; unary +? beq eval_number0 ; brif so - skip it @@ -122,12 +124,12 @@ rol val0+val.int+2 rol val0+val.int+1 rol val0+val.int - rol val0+val.fpexp ; overflow into fp exponent + rol val0+val.fpsexp ; overflow into fp exponent lsl val0+val.int+3 ; times 4 rol val0+val.int+2 rol val0+val.int+1 rol val0+val.int - rol val0+val.fpexp ; brif overflowed + rol val0+val.fpsexp ; brif overflowed ldd val0+val.int+2 ; times 5 (add original value) addd ,s++ std val0+val.int+2 @@ -135,14 +137,14 @@ adcb 1,s adca ,s++ std val0+val.int - ldb val0+val.fpexp ; and handle overflow bits + ldb val0+val.fpsexp ; and handle overflow bits adcb #0 - stb val0+val.fpexp + stb val0+val.fpsexp lsl val0+val.int+3 ; times 10 rol val0+val.int+2 rol val0+val.int+1 rol val0+val.int - rol val0+val.fpexp + rol val0+val.fpsexp ldd val0+val.int+2 ; get low word addb ,s+ ; add in current digit adca #0 @@ -151,9 +153,9 @@ adcb #0 adca #0 std val0+val.int - lda val0+val.fpexp ; and handle overflow + lda val0+val.fpsexp ; and handle overflow adca #0 - sta val0+val.fpexp + sta val0+val.fpsexp bne eval_number11 ; if we overflowed, go continue parsing as floating point lda val0+val.int ; get back high byte and check for overflow bpl eval_number4 ; brif we haven't wrapped negative @@ -167,28 +169,28 @@ beq eval_number8 ; brif so cmpa #'e ; base 10 exponent in lower case? beq eval_number8 ; brif so - ldb val0+val.fpsign ; did we want a negative value? + ldb val0+val.fpssign ; did we want a negative value? beq eval_number7 ; brif not jsr val_negint32 ; negate the 32 bit integer to correct two's complement -eval_number7 clr val0+val.fpsign ; clear sign bits for book keeping +eval_number7 clr val0+val.fpssign ; clear sign bits for book keeping rts eval_number11 jsr nextchar ; each the character already processed eval_number8 lda #0x9f ; exponent if binary point is to the right of the mantissa clr val0extra ; clear extra precision bits for val0 ldb #valtype_float ; flag value as floating point stb val0+val.type - ldb val0+val.fpexp ; do we have overflow bits to shift? + ldb val0+val.fpsexp ; do we have overflow bits to shift? beq eval_number10 ; brif not eval_number9 inca ; bump exponent to account for extra bits lsrb ; shift some bits over - ror val0+val.fpmant - ror val0+val.fpmant+1 - ror val0+val.fpmant+2 - ror val0+val.fpmant+3 + ror val0+val.fpssig + ror val0+val.fpssig+1 + ror val0+val.fpssig+2 + ror val0+val.fpssig+3 ror val0extra tstb ; all bits shifted into mantissa? bne eval_number9 ; brif not -eval_number10 sta val0+val.fpexp ; save adjusted exponent +eval_number10 sta val0+val.fpsexp ; save adjusted exponent ldx #val0 ; normalize the result for further operations jsr fp_normalize clr ,-s ; flag for decimal point seen @@ -261,6 +263,7 @@ jsr val_int32tofloat ; convert to floating point jsr fp_add ; add val1 to val0 bra eval_number40 ; go handle another character + endc ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Operator table ;