Firmware: fix loading of partial-size BS dumps

src/memory.c

@@ -210,7 +210,7 @@ uint32_t load_rom(uint8_t* filename, uint32_t base_addr, uint8_t flags) {
     printf("reconfigure FPGA with %s...\n", romprops.fpga_conf);
     fpga_pgm((uint8_t*)romprops.fpga_conf);
   }
-  set_mcu_addr(base_addr);
+  set_mcu_addr(base_addr + romprops.load_address);
   file_open(filename, FA_READ);
   ff_sd_offload=1;
   sd_offload_tgt=0;

src/smc.c

@@ -59,6 +59,7 @@ void smc_id(snes_romprops_t* props) {
   uint8_t score, maxscore=1, score_idx=2; /* assume LoROM */
   snes_header_t* header = &(props->header);
 
+  props->load_address = 0;
   props->has_dspx = 0;
   props->has_st0010 = 0;
   props->has_cx4 = 0;
@@ -95,6 +96,14 @@ void smc_id(snes_romprops_t* props) {
           props->expramsize_bytes = 0;
           props->mapper_id = 3; /* BS-X Memory Map */
           props->region = 0; /* BS-X only existed in Japan */
+          uint8_t alloc = header->name[0x10];
+          if(alloc) {
+            while(!(alloc & 0x01)) {
+              props->load_address += 0x20000;
+              alloc >>= 1;
+            }
+          }
+          printf("load address: %lx\n", props->load_address);
           return;
         }
       }

src/smc.h

@@ -84,6 +84,7 @@ typedef struct _snes_romprops {
   uint8_t has_cx4;            /* CX4 presence flag */
   uint8_t fpga_features;      /* feature/peripheral enable bits*/
   uint8_t region;             /* game region (derived from destination code) */
+  uint32_t load_address;      /* where to load the ROM image */
   snes_header_t header;       /* original header from ROM image */
 } snes_romprops_t;