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Implement opt Q for fixed-point precision, and q literals (e.g. 12.34q8) (#958)

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Fixes #957

Co-authored-by: ISSOtm <eldredhabert0@gmail.com>
This commit is contained in:
Rangi
2022-09-04 18:47:32 -04:00
committed by GitHub
parent 889302a9e2
commit 98a6dffbca
20 changed files with 253 additions and 56 deletions
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74
src/asm/lexer.c
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@@ -27,6 +27,7 @@
#include "platform.h" // For `ssize_t`
#include "asm/lexer.h"
#include "asm/fixpoint.h"
#include "asm/format.h"
#include "asm/fstack.h"
#include "asm/macro.h"
@@ -1125,39 +1126,66 @@ static uint32_t readNumber(int radix, uint32_t baseValue)
return value;
}
static uint32_t readFractionalPart(int32_t integer)
static uint32_t readFractionalPart(uint32_t integer)
{
uint32_t value = 0, divisor = 1;
uint8_t precision = 0;
enum {
READFRACTIONALPART_DIGITS,
READFRACTIONALPART_PRECISION,
READFRACTIONALPART_PRECISION_DIGITS,
} state = READFRACTIONALPART_DIGITS;
for (;; shiftChar()) {
int c = peek();
if (c == '_')
continue;
else if (c < '0' || c > '9')
break;
if (divisor > (UINT32_MAX - (c - '0')) / 10) {
warning(WARNING_LARGE_CONSTANT,
"Precision of fixed-point constant is too large\n");
// Discard any additional digits
shiftChar();
while (c = peek(), (c >= '0' && c <= '9') || c == '_')
if (state == READFRACTIONALPART_DIGITS) {
if (c == '_') {
continue;
} else if (c == 'q' || c == 'Q') {
state = READFRACTIONALPART_PRECISION;
continue;
} else if (c < '0' || c > '9') {
break;
}
if (divisor > (UINT32_MAX - (c - '0')) / 10) {
warning(WARNING_LARGE_CONSTANT,
"Precision of fixed-point constant is too large\n");
// Discard any additional digits
shiftChar();
break;
while (c = peek(), (c >= '0' && c <= '9') || c == '_')
shiftChar();
break;
}
value = value * 10 + (c - '0');
divisor *= 10;
} else {
if (c == '.' && state == READFRACTIONALPART_PRECISION) {
state = READFRACTIONALPART_PRECISION_DIGITS;
continue;
} else if (c < '0' || c > '9') {
break;
}
precision = precision * 10 + (c - '0');
}
value = value * 10 + (c - '0');
divisor *= 10;
}
if (integer > INT16_MAX || integer < INT16_MIN)
if (precision == 0) {
if (state >= READFRACTIONALPART_PRECISION)
error("Invalid fixed-point constant, no significant digits after 'q'\n");
precision = fixPrecision;
} else if (precision > 31) {
error("Fixed-point constant precision must be between 1 and 31\n");
precision = fixPrecision;
}
if (integer >= ((uint32_t)1 << (precision - 1)))
warning(WARNING_LARGE_CONSTANT, "Magnitude of fixed-point constant is too large\n");
// Cast to unsigned avoids UB if shifting discards bits
integer = (uint32_t)integer << 16;
// Cast to unsigned avoids undefined overflow behavior
uint16_t fractional = (uint16_t)round(value * 65536.0 / divisor);
uint32_t fractional = (uint32_t)round((double)value / divisor * pow(2.0, precision));
return (uint32_t)integer | (fractional * (integer >= 0 ? 1 : -1));
return (integer << precision) | fractional;
}
char binDigits[2];
@@ -1741,6 +1769,8 @@ static int yylex_SKIP_TO_ENDC(void); // forward declaration for yylex_NORMAL
static int yylex_NORMAL(void)
{
uint32_t num = 0;
for (;;) {
int c = nextChar();
char secondChar;
@@ -1912,10 +1942,12 @@ static int yylex_NORMAL(void)
case '7':
case '8':
case '9':
yylval.constValue = readNumber(10, c - '0');
num = readNumber(10, c - '0');
if (peek() == '.') {
shiftChar();
yylval.constValue = readFractionalPart(yylval.constValue);
yylval.constValue = readFractionalPart(num);
} else {
yylval.constValue = num;
}
return T_NUMBER;