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(svn r8855) -Fix 

Change some shift and cast mumbo jumbo for inflation calculation to something remotly comprehensible and explain what the magic number "54" means
This commit is contained in:
tron 2007-02-23 08:03:30 +00:00
parent 8ace4dd25c
commit 9cbc49b65b
1 changed files with 10 additions and 7 deletions
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17
src/economy.cpp
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@ -613,18 +613,21 @@ static void PlayersGenStatistics(void)
static void AddSingleInflation(int32 *value, uint16 *frac, int32 amt) static void AddSingleInflation(int32 *value, uint16 *frac, int32 amt)
{ {
int64 tmp = (int64)*value * amt; int64 tmp = (int64)*value * amt + *frac;
int32 low; *frac = GB(tmp, 0, 16);
*frac = (uint16)(low = (uint16)tmp + *frac); *value += tmp >> 16;
*value += (int32)(tmp >> 16) + (low >> 16);
} }
static void AddInflation(void) static void AddInflation(void)
{ {
int i; /* Approximation for (100 + infl_amount)% ** (1 / 12) - 100%
* scaled by 65536
* 12 -> months per year
* This is only a good approxiamtion for small values
*/
int32 inf = _economy.infl_amount * 54; int32 inf = _economy.infl_amount * 54;
for (i = 0; i != NUM_PRICES; i++) { for (uint i = 0; i != NUM_PRICES; i++) {
AddSingleInflation((int32*)&_price + i, _price_frac + i, inf); AddSingleInflation((int32*)&_price + i, _price_frac + i, inf);
} }
@ -634,7 +637,7 @@ static void AddInflation(void)
_economy.max_loan += 50000; _economy.max_loan += 50000;
inf = _economy.infl_amount_pr * 54; inf = _economy.infl_amount_pr * 54;
for (i = 0; i != NUM_CARGO; i++) { for (uint i = 0; i != NUM_CARGO; i++) {
AddSingleInflation( AddSingleInflation(
(int32*)_cargo_payment_rates + i, (int32*)_cargo_payment_rates + i,
_cargo_payment_rates_frac + i, _cargo_payment_rates_frac + i,