Created address translation fast path for code reads, separated slow path into separa...

[pistorm] / m68kcpu.h

diff --git a/m68kcpu.h b/m68kcpu.h
index 0be9551eb59f710ed440cd18cfbf22d80d99cd75..38d6b9f8eff29a54dea4a5869c852ae79a38b957 100644 (file)
--- a/m68kcpu.h
+++ b/m68kcpu.h
@@ -1075,6 +1075,13 @@ char* m68ki_disassemble_quick(unsigned int pc, unsigned int cpu_type);
 
 
 /* ---------------------------- Read Immediate ---------------------------- */
+typedef struct
+{
+    unsigned int lower;
+    unsigned int upper;
+    unsigned char *data;
+} address_translation_cache;
+
 
 extern unsigned char read_ranges;
 extern unsigned int read_addr[8];
@@ -1085,6 +1092,8 @@ extern unsigned int write_addr[8];
 extern unsigned int write_upper[8];
 extern unsigned char *write_data[8];
 
+extern address_translation_cache code_translation_cache;
+
 // clear the instruction cache
 inline void m68ki_ic_clear()
 {
@@ -1152,56 +1161,24 @@ static inline uint32 m68ki_ic_readimm16(uint32 address)
 /* Handles all immediate reads, does address error check, function code setting,
  * and prefetching if they are enabled in m68kconf.h
  */
-static inline uint m68ki_read_imm_16(void)
-{
-       uint32_t address = ADDRESS_68K(REG_PC);
-       for (int i = 0; i < read_ranges; i++) {
-               if(address >= read_addr[i] && address < read_upper[i]) {
-                       REG_PC += 2;
-                       return be16toh(((unsigned short *)(read_data[i] + (address - read_addr[i])))[0]);
-               }
-       }
+uint m68ki_read_imm6_addr_slowpath(uint32_t address, address_translation_cache *cache);
 
-       m68ki_set_fc(FLAG_S | FUNCTION_CODE_USER_PROGRAM); /* auto-disable (see m68kcpu.h) */
-       m68ki_cpu.mmu_tmp_fc = FLAG_S | FUNCTION_CODE_USER_PROGRAM;
-       m68ki_cpu.mmu_tmp_rw = 1;
-       m68ki_cpu.mmu_tmp_sz = M68K_SZ_WORD;
-       m68ki_check_address_error(REG_PC, MODE_READ, FLAG_S | FUNCTION_CODE_USER_PROGRAM); /* auto-disable (see m68kcpu.h) */
 
-#if M68K_EMULATE_PREFETCH
-{
-       uint result;
-       if(REG_PC != CPU_PREF_ADDR)
-       {
-               CPU_PREF_DATA = m68ki_ic_readimm16(REG_PC);
-               CPU_PREF_ADDR = m68ki_cpu.mmu_tmp_buserror_occurred ? ((uint32)~0) : REG_PC;
-       }
-       result = MASK_OUT_ABOVE_16(CPU_PREF_DATA);
-       REG_PC += 2;
-       if (!m68ki_cpu.mmu_tmp_buserror_occurred) {
-               // prefetch only if no bus error occurred in opcode fetch
-               CPU_PREF_DATA = m68ki_ic_readimm16(REG_PC);
-               CPU_PREF_ADDR = m68ki_cpu.mmu_tmp_buserror_occurred ? ((uint32)~0) : REG_PC;
-               // ignore bus error on prefetch
-               m68ki_cpu.mmu_tmp_buserror_occurred = 0;
-       }
-       return result;
-}
-#else
 
+static inline uint m68ki_read_imm_16(void)
+{
        uint32_t address = ADDRESS_68K(REG_PC);
-       REG_PC += 2;
 
-       for (int i = 0; i < read_ranges; i++) {
-               if(address >= read_addr[i] && address < read_upper[i]) {
-                       return be16toh(((unsigned short *)(read_data[i] + (address - read_addr[i])))[0]);
-               }
-       }
-
-       return m68k_read_immediate_16(address);
-#endif /* M68K_EMULATE_PREFETCH */
+    address_translation_cache *cache = &code_translation_cache;
+    if(address >= cache->lower && address < cache->upper)
+    {
+        REG_PC += 2;
+        return be16toh(((unsigned short *)(cache->data + (address - cache->lower)))[0]);
+    }
+    return m68ki_read_imm6_addr_slowpath(address, cache);
 }
 
+
 static inline uint m68ki_read_imm_8(void)
 {
        /* map read immediate 8 to read immediate 16 */