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Refactor some math functions into a shared file for rgbasm and rgblink

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Fixes #769

Fixes #770
This commit is contained in:
Rangi
2021-02-28 16:50:47 -05:00
committed by Eldred Habert
parent 0774f5eb9d
commit ac2cefdd87
7 changed files with 151 additions and 177 deletions
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84
src/link/patch.c
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@@ -18,82 +18,10 @@
#include "link/symbol.h"
#include "linkdefs.h"
#include "opmath.h"
#include "extern/err.h"
static int32_t divide(int32_t dividend, int32_t divisor)
{
// Adjust division to floor toward negative infinity,
// not truncate toward zero
return dividend / divisor - ((dividend % divisor < 0) != (divisor < 0));
}
static int32_t modulo(int32_t dividend, int32_t divisor)
{
int32_t remainder = dividend % divisor;
// Adjust modulo to have the sign of the divisor,
// not the sign of the dividend
return remainder + divisor * ((remainder < 0) != (divisor < 0));
}
static int32_t exponent(int32_t base, uint32_t power)
{
int32_t result = 1;
for (;;) {
if (power % 2)
result *= base;
power /= 2;
if (!power)
break;
base *= base;
}
return result;
}
static int32_t asl(int32_t value, int32_t shiftamt); // Forward decl for below
static int32_t asr(int32_t value, int32_t shiftamt)
{
uint32_t uvalue = value;
// Get the easy cases out of the way
if (shiftamt == 0)
return value;
if (value == 0 || shiftamt <= -32)
return 0;
if (shiftamt > 31)
return (value < 0) ? -1 : 0;
if (shiftamt < 0)
return asl(value, -shiftamt);
if (value > 0)
return uvalue >> shiftamt;
{
// Calculate an OR mask for sign extension
// 1->0x80000000, 2->0xC0000000, ..., 31->0xFFFFFFFE
uint32_t shiftamt_high_bits = -((uint32_t)1 << (32 - shiftamt));
return (uvalue >> shiftamt) | shiftamt_high_bits;
}
}
static int32_t asl(int32_t value, int32_t shiftamt)
{
// Repeat the easy cases here to avoid INT_MIN funny business
if (shiftamt == 0)
return value;
if (value == 0 || shiftamt >= 32)
return 0;
if (shiftamt < -31)
return (value < 0) ? -1 : 0;
if (shiftamt < 0)
return asr(value, -shiftamt);
return (uint32_t)value << shiftamt;
}
/*
* This is an "empty"-type stack. Apart from the actual values, we also remember
* whether the value is a placeholder inserted for error recovery. This allows
@@ -251,7 +179,7 @@ static int32_t computeRPNExpr(struct Patch const *patch,
popRPN();
value = INT32_MAX;
} else {
value = divide(popRPN(), value);
value = op_divide(popRPN(), value);
}
break;
case RPN_MOD:
@@ -263,7 +191,7 @@ static int32_t computeRPNExpr(struct Patch const *patch,
popRPN();
value = 0;
} else {
value = modulo(popRPN(), value);
value = op_modulo(popRPN(), value);
}
break;
case RPN_UNSUB:
@@ -278,7 +206,7 @@ static int32_t computeRPNExpr(struct Patch const *patch,
popRPN();
value = 0;
} else {
value = exponent(popRPN(), value);
value = op_exponent(popRPN(), value);
}
break;
@@ -332,11 +260,11 @@ static int32_t computeRPNExpr(struct Patch const *patch,
case RPN_SHL:
value = popRPN();
value = asl(popRPN(), value);
value = op_shift_left(popRPN(), value);
break;
case RPN_SHR:
value = popRPN();
value = asr(popRPN(), value);
value = op_shift_right(popRPN(), value);
break;
case RPN_BANK_SYM: