[Tinycc-devel] Question about tcc (C67) assembler code.

[Kim Lux]

Could someone explain how the code in the C67_asm(char *s, int a, int b,
int c) routine works ?

What are the "<<23"s about ?

BTW: I generally find the tcc code to be well written and
understandable.  No knocks against this code, I just don't understand
what it is doing at first glance.

Here is an example instruction.  How does it work ?

If one is writing a new assembler, should it be done in the same way ?

else if (strstr(s, "AND.L") == s) {
        xpath = C67_map_regs(b) ^ C67_map_regs(c);

        ALWAYS_ASSERT(C67_map_regs(a) == C67_map_regs(c));

        C67_g((0 << 29) |       //creg
              (0 << 28) |       //inv
              (C67_map_regn(c) << 23) | //dst
              (C67_map_regn(b) << 18) | //src2 (possible x path)
              (C67_map_regn(a) << 13) | //src1 
              (xpath << 12) |   //x cross path if opposite sides
              (0x7b << 5) |     //opcode
              (0x6 << 2) |      //opcode fixed
              (C67_map_regs(c) << 1) |  //side of dest
              (0 << 0));        //parallel

-- 
Kim Lux,  Diesel Research Inc.