64 lines
1.5 KiB
C
64 lines
1.5 KiB
C
#include <string.h>
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#include <ctype.h>
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#include <endianness.h>
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#include <fxg1a.h>
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/*
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** Public API
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*/
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/* checksum(): Sum of 8 big-endian shorts at 0x300 */
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uint16_t checksum(struct g1a const *g1a, size_t size)
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{
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uint16_t shorts[16] = { 0 };
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/* Extract 16 bytes from the file (maybe less are available) */
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int available = size - 0x300;
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if(available < 0) available = 0;
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if(available > 16) available = 16;
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memcpy(shorts, g1a->code + 0x100, available);
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/* Do the big-endian sum */
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uint16_t sum = 0;
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for(int i = 0; i < 8; i++) sum += htobe16(shorts[i]);
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return sum;
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}
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/* default_output(): Calculate default output file name */
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void default_output(const char *name, const char *suffix, char *output)
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{
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/* Check if there is a dot at the end of @name, before the last '/'.
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The dot must also not be in first position (hidden files) */
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size_t end = strlen(name) - 1;
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while(end >= 1 && name[end] != '/' && name[end] != '.') end--;
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/* If we don't have a dot in the file name, append the extension */
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if(end < 1 || name[end] != '.')
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{
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strcpy(output, name);
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strcat(output, suffix);
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}
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/* If we found a dot before the last slash, replace the extension */
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else
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{
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memcpy(output, name, end);
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strcpy(output + end, suffix);
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}
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}
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/* default_internal(): Calculate default internal name */
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void default_internal(const char *name, char *output)
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{
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output[0] = '@';
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int i=1;
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for(int j=0; name[j] && i < 8; j++)
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{
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if(isalpha(name[j])) output[i++] = toupper(name[j]);
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}
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output[i] = 0;
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}
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