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clean up floats, floats which become infinity and zero

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This commit is contained in:
pommicket 2022-01-12 15:44:44 -05:00
parent ee3c461e6e
commit e43f32b932
2 changed files with 51 additions and 43 deletions
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2
05/main.c
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@ -2,4 +2,4 @@
char * = "How are you"" d""o""i""ng today?\n";
hi
_TEST _ING _1
50.1e100
5e+307

92
05/tokenize.b
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@ -283,28 +283,9 @@ function tokenize
:float_no_fraction
; construct the number integer + fraction*10^pow10
; first, deal with the fractional part
p = powers_of_10
p += pow10 < 4
full_multiply_signed(fraction, *8p, &lower, &upper)
if upper == 0 goto fmultiply_no_upper
n = leftmost_1bit(upper)
n += 1
significand = lower > n
exponent += n
n = 64 - n
significand |= upper < n
goto fmultiply_cont
:fmultiply_no_upper
significand = lower
goto fmultiply_cont
:fmultiply_cont
p += 8
exponent += *8p
significand = fraction
float_multiply_by_power_of_10(&significand, &exponent, pow10)
putn(significand)
putc(32)
putn_signed(exponent)
putc(10)
if integer == 0 goto float_no_integer
; now deal with the integer part
new_exponent = leftmost_1bit(integer)
@ -324,7 +305,9 @@ function tokenize
putc(32)
putn_signed(exponent)
putc(10)
significand += 15 ; ensure number rounds to the nearest representable float (this is what gcc does)
; make number round to the nearest representable float roughly (this is what gcc does)
; this fails for 5e-100 probably because of imprecision, but mostly works
significand += 15
; reduce to 53-bit significand (top bit is removed to get 52)
significand >= 5
exponent += 5
@ -333,6 +316,9 @@ function tokenize
b = 1 < n
significand &= ~b
data = significand
if exponent <= -1023 goto float_zero ; this number is too small in magnitude to be represented as a double. it becomes 0
if exponent >= 1024 goto float_infinity ; number too big to be represented as a double.
exponent += 1023 ; float format
data |= exponent < 52
@ -351,23 +337,7 @@ function tokenize
; e.g. 1e100
pow10 = strtoi(&in, 10)
:float_have_exponent
p = powers_of_10
p += pow10 < 4
full_multiply_signed(significand, *8p, &lower, &upper)
if upper == 0 goto fmultiply2_no_upper
n = leftmost_1bit(upper)
n += 1
significand = lower > n
exponent += n
n = 64 - n
significand |= upper < n
goto fmultiply2_cont
:fmultiply2_no_upper
significand = lower
goto fmultiply2_cont
:fmultiply2_cont
p += 8
exponent += *8p
float_multiply_by_power_of_10(&significand, &exponent, pow10)
goto float_have_significand_and_exponent
:float_exponent_plus
; e.g. 1e+100
@ -381,8 +351,11 @@ function tokenize
pow10 = 0 - pow10
goto float_have_exponent
:float_zero
data = 0
goto float_have_data
data = 0
goto float_have_data
:float_infinity
data = 0x7ff0000000000000 ; double infinity
goto float_have_data
:tokenize_loop_end
return 0
@ -416,7 +389,42 @@ function tokenize
:str_bad_float
string Bad floating-point number.
byte 0
function float_multiply_by_power_of_10
argument p_significand
argument p_exponent
argument pow10
local significand
local exponent
local p
local lower
local upper
local n
significand = *8p_significand
exponent = *8p_exponent
p = powers_of_10
p += pow10 < 4
full_multiply_signed(significand, *8p, &lower, &upper)
if upper == 0 goto fmultiply2_no_upper
n = leftmost_1bit(upper)
n += 1
significand = lower > n
exponent += n
n = 64 - n
significand |= upper < n
goto fmultiply2_cont
:fmultiply2_no_upper
significand = lower
goto fmultiply2_cont
:fmultiply2_cont
p += 8
exponent += *8p
*8p_significand = significand
*8p_exponent = exponent
return 0
; return character or escaped character from *p_in, advancing accordingly
; returns -1 on bad character
function read_c_char