mirror of https://github.com/pevans/erc-c.git
105 lines
2.9 KiB
C
105 lines
2.9 KiB
C
/*
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* objstore.c
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*
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* The code here allows us to work with the object store, which is an
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* entity that allows us to toss all of our binary data needs into a big
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* glob of stuff that we can unpack and use at runtime. Examples of such
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* data are bitmap fonts, ROM data, etc.
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*/
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#include <zlib.h>
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#include "objstore.h"
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#include "objstore_data.h"
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/*
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* This is data that we expect to find in the store_data variable that
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* is defined in objstore_data.h.
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*/
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#define HEADER_DATA "hope"
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/*
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* Our object store. Just a simple struct that we pull data out from.
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*/
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static objstore store;
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/*
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* This function will set up the store variable so that it contains
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* useful information rather than garbage data from the stack. It does
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* so with a simply memcpy from store_data directly into store, such
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* that the store data itself can be aligned for access.
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*/
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int
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objstore_init()
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{
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// Oh, you're calling this again? Cool, but let's bail before we do
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// anything else.
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if (objstore_ready()) {
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return OK;
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}
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// We want to input some bad header data and compare with what
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// eventually should get put into there by memcmp.
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store.header[0] = 'h';
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store.header[1] = 'e';
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store.header[2] = 'y';
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store.header[3] = '\0';
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memcpy(&store, store_data, sizeof(store));
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// If the copy didn't work out somehow...
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if (!objstore_ready()) {
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log_crit("Object store initialization failed with bad data");
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return ERR_BADFILE;
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}
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return OK;
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}
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/*
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* This will empty out the store, which is not very _practically_
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* useful, but is a bit useful when testing.
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*/
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void
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objstore_clear()
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{
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memset(&store, 0, sizeof(store));
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}
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/*
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* Return true if the object store is ready to be used.
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*/
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bool
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objstore_ready()
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{
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int cmp;
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// Test if the header field data is exactly equivalent to that
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// defined in HEADER_DATA. Note we use memcmp(), because the header
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// field is an array of just 4 bytes; strcmp() and strncmp() have an
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// expectation that both pointers will be directed at NUL-terminated
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// strings, which is _not_ the case for store.header (but,
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// incidentally, _is_ the case for HEADER_DATA!).
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cmp = memcmp(store.header, HEADER_DATA,
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sizeof(store.header) / sizeof(char));
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return cmp == 0;
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}
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/*
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* Something to simplify the very simple getter functions we use for
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* getting data from the object store.
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*/
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#define OBJSTORE_DEFN(x) \
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const vm_8bit *objstore_##x() { return store.x; }
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/*
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* Note we have an extra semicolon on the end... this is mostly to avoid
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* screwing up my indent, to be honest. But C will ignore the
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* semicolons, so all is well.
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*/
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OBJSTORE_DEFN(apple2_peripheral_rom); // ignore docblock
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OBJSTORE_DEFN(apple2_sys_rom); // ignore docblock
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OBJSTORE_DEFN(apple2_sysfont); // ignore docblock
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OBJSTORE_DEFN(apple2_invfont); // ignore docblock
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