diff options
| author | Ian C <ianc@noddybox.co.uk> | 2016-05-04 15:31:43 +0100 |
|---|---|---|
| committer | Ian C <ianc@noddybox.co.uk> | 2016-05-04 15:31:43 +0100 |
| commit | d66326a6717195dc93602d2f9af24f3411b25dd9 (patch) | |
| tree | 6aa7c4ef432417ab17317692d2b87e062ef52509 | |
| parent | a395d7bf01456620806ae521878a60bdad8dc6e5 (diff) | |
First (bad) attempt at SNES checksum.
| -rw-r--r-- | src/snesout.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/src/snesout.c b/src/snesout.c index 1612a6b..911ee49 100644 --- a/src/snesout.c +++ b/src/snesout.c @@ -133,6 +133,16 @@ static int PokeS(Byte *mem, int addr, const char *str, int maxlen, char pad) return addr; } +static unsigned CalcChecksum(Byte *p, int len, unsigned csum) +{ + while(len-- > 0) + { + csum += *p++; + } + + return csum & 0xffff; +} + /* ---------------------------------------- INTERFACES */ @@ -198,6 +208,7 @@ int SNESOutput(const char *filename, const char *filename_bank, int base; int len; int f; + unsigned csum; /* If the ROM type is LOROM then we assume each bank holds 32Kb. Otherwise each bank is a full 64Kb. @@ -275,7 +286,17 @@ int SNESOutput(const char *filename, const char *filename_bank, PokeB(mem, 0xffd8, option.ram_size); - /* TODO: Need checksums? */ + /* Calculate checksum + */ + csum = 0; + + for(f = 0; f < count; f++) + { + csum = CalcChecksum(bank[f]->memory + base, len, csum); + } + + PokeW(mem, 0xffde, csum); + PokeW(mem, 0xffdc, 0xffffu - csum); /* Output ROM contents */ |