diff options
| -rw-r--r-- | zruntime.S | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/zruntime.S b/zruntime.S new file mode 100644 index 0000000..9e98f10 --- /dev/null +++ b/zruntime.S @@ -0,0 +1,239 @@ +z_inccycles: + cmp %edi, %ebp + jnb do_limit +no_sync: + add $3, %ebp + ret +do_limit: + cmp 112(%rsi), %ebp + jb no_sync + call z80_save_context_scratch + pop %rax /*return address in read/write func*/ + pop 104(%rsi) /*return address in native code*/ + sub $5, %rax /* adjust return addres to point to the call instruction that got us here */ + mov %rax, (%rsi) + + pop %r15 /* restore callee saved regsiters */ + pop %r14 + pop %r13 + pop %r12 + pop %rbp + pop %rbx + ret /* return to caller of z80_run */ + + .global z80_handle_cycle_limit_int +z80_handle_cycle_limit_int: + cmp 116(%rsi), %ebp + jb zskip_int + mov 112(%rsi), %ebp /* set cycle limit to sync cycle */ + add $7, %ebp + sub $2, %r9w + mov %r9w, %r13w + call z_inccycles + push %r14 + call z80_write_byte_noinc + pop %r14 + mov %r9w, %r13w + add $1, %r13w + shr $8, %r14w + call z_inccycles + call z80_write_byte_noinc + /* TODO: Support interrupt mode 0 and 2 */ + mov $0x38, %r13w + call z80_native_addr + jmp *%r13 +zskip_int: + cmp 112(%rsi), %ebp + jb zskip_sync + call z80_save_context + .global z80_do_sync +z80_do_sync: + pop (%rsi) /*return address in native code*/ + pop %r15 /* restore callee saved regsiters */ + pop %r14 + pop %r13 + pop %r12 + pop %rbp + pop %rbx +zskip_sync: + ret + + .global z80_read_byte +z80_read_byte: + call z_inccycles +z80_read_byte_noinc: + cmp $0x4000, %r13w + jb z80_read_ram + cmp $0x8000, %r13w + jae z80_read_bank + /* TODO: Bank reg, YM-2612, PSG/VDP */ + ret +z80_read_ram: + and $0x1FFF, %r13 + mov (%r11, %r13), %r13b + ret +z80_read_bank: + and $0x7FFF, %r13 + cmp $0, %r12 + je slow_bank_read + /* 68K memory is byte swapped */ + xor $1, %r13 + mov (%r12, %r13), %r13b + ret +slow_bank_read: + /* TODO: Call into C to implement this */ + ret + + .global z80_write_byte +z80_write_byte: + call z_inccycles +z80_write_byte_noinc: + cmp $0x4000, %r13w + jb z80_write_ram + cmp $0x8000, %r13w + jae z80_write_bank + cmp $0x6000, %r13w + je z80_write_bank_reg + /* TODO: YM-2612, PSG/VDP */ + ret +z80_write_ram: + and $0x1FFF, %r13 + mov %r14b, (%r11, %r13) + ret +z80_write_bank: + and $0x7FFF, %r13 + cmp $0, %r12 + je slow_bank_write + /* 68K memory is byte swapped */ + xor $1, %r13 + mov %r14b, (%r12, %r13) + ret +slow_bank_write: + /* TODO: Call into C to implement this */ + ret +z80_write_bank_reg: + and $1, %r14w + shl %r15w + or %r14w, %r15w + and $0x1FF, %r15w + xor %r12, %r12 + cmp $0x80, %r15w + jb update_bank_ptr + ret +update_bank_ptr: + mov %r15w, %r12w + shl $15, %r12 + add 80(%rsi), %r12 + ret + + .global z80_read_word +z80_read_word: + call z_inccycles + push %r13 + call z80_read_byte_noinc + mov %r13b, %r14b + pop %r13 + inc %r13 + call z_inccycles + call z80_read_byte_noinc + shl $8, %r13w + mov %r14b, %r13b + ret + + .global z80_write_word_highfirst +z80_write_word_highfirst: + call z_inccycles + push %r14 + push %r13 + add $1, %r13w + shr $8, %r14w + call z80_write_byte_noinc + pop %r13 + pop %r14 + call z_inccycles + call z80_write_byte_noinc + ret + + .global z80_write_word_lowfirst +z80_write_word_lowfirst: + call z_inccycles + push %r14 + push %r13 + call z80_write_byte_noinc + pop %r13 + pop %r14 + add $1, %r13w + shr $8, %r14w + call z_inccycles + call z80_write_byte_noinc + ret + + .global z80_native_addr +z80_native_addr: + call z80_save_context + push %rsi + mov %rsi, %rdi + movzx %r13w, %esi + call z80_get_native_address_trans + mov %rax, %r13 + pop %rsi + call z80_load_context + ret + +z80_save_context_scratch: + mov %r13w, 98(%rsi) /* scratch1 */ + mov %r14w, 100(%rsi) /* scratch2 */ + + .global z80_save_context +z80_save_context: + mov %r9w, 8(%rsi) /* SP */ + mov %r15w, 16(%rsi) /* bank register */ + mov %bx, 18(%rsi) /* BC */ + mov %cx, 20(%rsi) /* DE */ + mov %ax, 22(%rsi) /* HL */ + mov %dx, 24(%rsi) /* IX */ + mov %r8w, 26(%rsi) /* IY */ + mov %r10b, 30(%rsi) /* A */ + mov %edi, 48(%rsi) /* target_cycle */ + mov %ebp, 52(%rsi) /* current_cycle */ + mov %r12, 72(%rsi) /* cartridge bank pointer */ + ret + + +z80_load_context_scratch: + mov 98(%rsi), %r13w /* scratch1 */ + mov 100(%rsi), %r14w /* scratch2 */ + + .global z80_load_context +z80_load_context: + mov 8(%rsi), %r9w /* SP */ + mov 16(%rsi), %r15w /* bank register */ + mov 18(%rsi), %bx /* BC */ + mov 20(%rsi), %cx /* DE */ + mov 22(%rsi), %ax /* HL */ + mov 24(%rsi), %dx /* IX */ + mov 26(%rsi), %r8w /* IY */ + mov 30(%rsi), %r10b /* A */ + mov 48(%rsi), %edi /* target_cycle */ + mov 52(%rsi), %ebp /* current_cycle */ + mov 64(%rsi), %r11 /* z80 RAM */ + mov 72(%rsi), %r12 /* cartridge bank pointer */ + ret + + .global z80_run +z80_run: + push %rbx + push %rbp + push %r12 + push %r13 + push %r14 + push %r15 + mov %rdi, %rsi + call z80_load_context_scratch + cmpq $0, 104(%rsi) + je no_extra + push 104(%rsi) + movq $0, 104(%rsi) +no_extra: + jmp *(%rsi) + |