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a25b28a972
cbm_load() is needed because the Pet/CBM Kernals don't have a LOAD function that can be used by machine code programs.
60 lines
1.7 KiB
C
60 lines
1.7 KiB
C
/*
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** 2020-10-15, Greg King
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**
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** unsigned int __fastcall__ cbm_load (const char* name,
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** unsigned char device,
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** void* data);
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*/
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#include <cbm.h>
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#include <limits.h>
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/* Loads file "name" from the given device to the given address, or to the load
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** address of the file if "data" is the null pointer (like load"name",8,1
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** in BASIC).
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** Returns the number of bytes that were loaded if loading was successful;
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** otherwise 0; "_oserror" contains an error-code, then.
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*/
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unsigned int __fastcall__ cbm_load (const char* name, unsigned char device, void* data)
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{
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void* load;
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int length;
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unsigned int size = 0;
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if (cbm_open (1, device, CBM_READ, name) != 0) {
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/* Can't load from a file that can't be openned. */
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return 0;
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}
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/* Get the file's load address. */
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if (cbm_read (1, &load, sizeof load) != sizeof load) {
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/* Either the file wasn't found, or it was too short. (Note:
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** the computer openned a file even if the drive couldn't open one.)
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*/
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cbm_close (1);
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return 0;
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}
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/* If "data" doesn't hold an address, then use the file's address. */
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if (data == (void*)0x0000) {
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data = load;
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}
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/* Pull the file into RAM. [Note that, if cbm_read() grabbed more
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** than 32767 bytes at a time, then its result would look negative,
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** which would cancel the load.]
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*/
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do {
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size += (length = cbm_read (1, data, INT_MAX));
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data = (unsigned char*)data + length;
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} while (length == INT_MAX && cbm_k_readst() == 0);
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cbm_close (1);
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/* "length" is -1 if there was an error. */
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if (length < 0) {
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size = 0;
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}
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return size;
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}
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