/* * ============================================================================ * OP_FORMAT: CP-1600 Opcode Formats * * Author: J. Zbiciak * * $Id$ * ============================================================================ * This header contains bitfield structures that define the various * CP-1600 opcode formats. This header should be compatible w/ jzIntv's * "op_decode.h". Eventually, op_decode.h should factor into two headers, * one of which is this one. * ============================================================================ */ #ifndef _OP_FORMAT_H #define _OP_FORMAT_H #include "config.h" /* * ============================================================================ * The CP-1610 is a 16-bit processor which stores its instructions in 10-bit * wide quantities known as "decles". (Rhymes w/ heckle.) Instructions * may be stored in 10-bit or 16-bit wide memory in the Intellivision. * * The CP-1610 supports the following basic opcode formats: * * Format Words Description * --------------------------------------- ----- ------------------------- * 0000 000 0oo 1 Implied 1-op insns * 0000 000 100 bbppppppii pppppppppp 3 Jump insns * 0000 000 1oo 1 Implied 1-op insns * 0000 ooo ddd 1 1-op insns, comb src/dst * 0000 110 0dd 1 GSWD * 0000 110 1om 1 NOP(2), SIN(2) * 0001 ooo mrr 1 Rotate/Shift insns * 0ooo sss ddd 1 2-op arith, reg->reg * 1000 zxc ccc pppppppppp 2 Branch insns * 1001 000 sss pppppppppp 2 2-op MVO , reg->direct * 1001 mmm sss 1* 2-op MVO@, reg->ind. * 1001 111 sss iiiiiiiiii 2* 2-op MVOI, reg->immed. * 1ooo 000 ddd pppppppppp 2 2-op arith, direct->reg * 1ooo mmm ddd 1* 2-op arith, ind. ->reg * 1ooo 111 ddd iiiiiiiiii 2* 2-op arith, immed.->reg * * * Key * --- * * oo -- Opcode field (dependent on format) * sss -- Source register, R0 ... R7 (binary encoding) * ddd -- Destination register, R0 ... R7 (binary encoding) * 0dd -- Destination register, R0 ... R3 * cccc -- Condition codes (branches) * x -- External branch condition (0 == internal, 1 == examine BEXT) * z -- Branch displacement direction (1 == negative) * m -- Shift amount (0 == shift by 1, 1 == shift by 2) * bb -- Branch return register * ii -- Branch interrupt flag mode * * Branch Condition Codes (cccc) * ---------------------- * n == 0 n == 1 * n000 -- Always Never * n001 -- Carry set/Greater than Carry clear/Less than or equal * n010 -- Overflow set Overflow clear * n011 -- Positive Negative * n100 -- Equal Not equal * n101 -- Less than Greater than or equal * n110 -- Less than or equal Greater than * n111 -- Unequal sign and carry Equal sign and carry * * Branch Return Registers (bb) * ----------------------- * * 00 -- R4 * 01 -- R5 * 10 -- R6 * 11 -- none (do not save return address) * * Branch Interrupt Modes (ii) * ---------------------- * * 00 -- Do not change interrupt enable state * 01 -- Enable interrupts * 10 -- Disable interrupts * 11 -- Undefined/Reserved ? * * SDBD notes: * * -- SDBD is supported on "immediate" and "indirect" modes only. * * -- An SDBD prefix on an immediate instruction sets the immediate constant * to be 16 bits, stored in two adjacent 8-bit words. The ordering is * little-endian. * * -- An SDBD prefix on an indirect instruction causes memory to be accessed * twice, bringing in (or out) two 8-bit words, again in little-endian * order. If a non-incrementing data counter is used, both accesses are * to the same address. Otherwise, the counter is post-incremented with * each access. Indirect through R6 (stack addressing) is not allowed. * * Interruptibility notes: * * -- Interrupts always occur after an instruction completes. No instruction * is interrupted midstream and completed later. * * -- Interrupts are taken after the completion of the next interruptible * instruction. A non-interruptible instruction masks interrupts through * the transition from the current instruction to the next. * * -- When the processor takes an interrupt, the current PC value is pushed * on the stack. The address jumped to for the interrupt is provided * by external hardware (similar to an 8080, if I recall correctly). * * Status register/GSWD/RSWD notes: * * -- The status register has the following format: * * 3 2 1 0 S -- Sign * +---+---+---+---+ Z -- Zero * | S | Z | O | C | O -- Overflow * +---+---+---+---+ C -- Carry * * -- The GSWD instruction stores the status word in the upper 4 bits of each * byte of the destination register: * * F E D C B A 9 8 7 6 5 4 3 2 1 0 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ * | S | Z | O | C | - | - | - | - | S | Z | O | C | - | - | - | - | * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ * * -- The RSWD instruction reads the status word's new value from the upper * four bits of the lower byte of the source register: * * 7 6 5 4 3 2 1 0 * +---+---+---+---+---+---+---+---+ * | S | Z | O | C | - | - | - | - | * +---+---+---+---+---+---+---+---+ * * SWAP notes: * * -- A "double" swap gives the original word, but sets S and Z status bits * based on the lower byte, apparently. This is based on the comments * in the following code snippet from RUNNING.SRC in the dev kit: * * SWAP R0, 2 ; check bit #7 * BMI @@exit ; max speed is 127 * * ============================================================================ */ /* * ============================================================================ * OP_IMPL_1OP_A -- Implied one-op instructions * * Format Words Description * --------------------------------------- ----- ------------------------- * 0000 000 0oo 1 Implied 1-op insns * ============================================================================ */ typedef struct op_impl_1op_a { BFE(unsigned op : 2, /* Can have all four values */ BFE(unsigned zero : 8, /* Must be zero! */ unsigned pad1 : 22)); /* Pad to 32-bit word */ } op_impl_1op_a; /* * ============================================================================ * OP_IMPL_1OP_B -- Implied one-op instructions * * Notes: * -- Opcode field cannot be 00. (That encoding is used by the Jump insns) * * Format Words Description * --------------------------------------- ----- ------------------------- * 0000 000 1oo 1 Implied 1-op insns * ============================================================================ */ typedef struct op_impl_1op_b { BFE(unsigned op : 2, /* Can have all four values */ BFE(unsigned one : 1, /* Must be one! */ BFE(unsigned zero : 7, /* Must be zero! */ unsigned pad1 : 22))); /* Pad to 32-bit word */ } op_impl_1op_b; /* * ============================================================================ * OP_JUMP -- Implied one-op instructions * * Notes: * -- Shares same 1st decle encoding as op_impl_1op_b, except op field == 0. * * Format Words Description * --------------------------------------- ----- ------------------------- * 0000 000 100 bbppppppii pppppppppp 3 Jump insns * ============================================================================ */ typedef struct op_jump { /* Word #1 */ BFE(unsigned op : 2, /* Can have all four values */ BFE(unsigned one : 1, /* Must be one! */ BFE(unsigned zero : 7, /* Must be zero! */ unsigned pad1 : 22))); /* Pad to 32-bit word */ /* Word #2 */ BFE(unsigned intr_mode : 2, /* 11 is invalid */ BFE(unsigned dst_msb : 6, /* MSBs of destination */ BFE(unsigned save_reg : 2, /* Register to save to */ unsigned pad2 : 22))); /* Pad to 32-bit word */ /* Word #3 */ BFE(unsigned dst_lsb : 10, /* LSBs of destination */ unsigned pad3 : 22); /* Pad to 32-bit word */ } op_jump; /* * ============================================================================ * OP_REG_1OP -- Register-based one-op instructions * * Notes: * -- Opcode 000 is taken by jump and impl_1op encodings * -- Opcode 110 aliases both GSWD encoding and NOP/SIN encoding. * * Format Words Description * --------------------------------------- ----- ------------------------- * 0000 ooo ddd 1 1-op insns, comb src/dst * ============================================================================ */ typedef struct op_reg_1op { BFE(unsigned dst : 3, /* Can have all 8 values */ BFE(unsigned op : 3, /* 000, 110 invalid */ BFE(unsigned zero : 4, /* Must be zero! */ unsigned pad1 : 22))); /* Pad to 32-bit word */ } op_reg_1op; /* * ============================================================================ * OP_GSWD -- Get status word * * Notes: * -- Only one instruction (GSWD) has this encoding. * -- Aliases reg_1op encoding's 110 opcode. * -- Very similar to nop_sin encoding (below) * * Format Words Description * --------------------------------------- ----- ------------------------- * 0000 110 0dd 1 GSWD * ============================================================================ */ typedef struct op_gswd { BFE(unsigned dst : 2, /* Can have all four values */ BFE(unsigned id : 4, /* Must be 1100 */ BFE(unsigned zero : 4, /* Must be zero! */ unsigned pad1 : 22))); /* Pad to 32-bit word */ } op_gswd; /* * ============================================================================ * OP_NOP_SIN -- NOP and SIN encoding * * Notes: * -- Only two instructions (NOP, SIN) have this encoding. * -- Aliases reg_1op encoding's 110 opcode. * -- Very similar to gswd encoding (above) * * Format Words Description * --------------------------------------- ----- ------------------------- * 0000 110 1om 1 NOP(2), SIN(2) * ============================================================================ */ typedef struct op_nop_sin { BFE(unsigned imm : 1, /* 0 == '1', 1 == '2' */ BFE(unsigned op : 1, /* 0 == NOP, 1 == SIN */ BFE(unsigned id : 4, /* Must be 1101 */ BFE(unsigned zero : 4, /* Must be zero! */ unsigned pad1 : 22)))); /* Pad to 32-bit word */ } op_nop_sin; /* * ============================================================================ * OP_ROT_1OP -- Rotate/Shift instructions, one-op * * Notes: * -- Aliases reg_2op's 001 opcode. * * Format Words Description * --------------------------------------- ----- ------------------------- * 0001 ooo mrr 1 Rotate/Shift insns * ============================================================================ */ typedef struct op_rot_1op { BFE(unsigned dst : 2, /* R0 .. R3 */ BFE(unsigned op : 4, /* All values valid */ BFE(unsigned id : 4, /* Must be 0001 */ unsigned pad1 : 22))); /* Pad to 32-bit word */ } op_rot_1op; /* * ============================================================================ * OP_REG_2OP -- Register->Register 2OP instructions * * Notes: * -- The 000 opcode is used by other opcode formats above. * -- The 001 opcode is used by rot_1op * * Format Words Description * --------------------------------------- ----- ------------------------- * 0ooo sss ddd 1 2-op arith, reg->reg * ============================================================================ */ typedef struct op_reg_2op { BFE(unsigned dst : 3, /* Dest. register (R0..R7) */ BFE(unsigned src : 3, /* Source register (R0..R7) */ BFE(unsigned op : 3, /* 000, 001 invalid */ BFE(unsigned zero : 1, /* Must be 0 */ unsigned pad1 : 22)))); /* Pad to 32-bit word */ } op_reg_2op; /* * ============================================================================ * OP_COND_BR -- Conditional branch * * Notes: * -- Uses 000 opcode from imm_2op, ind_2op, and dir_2op spaces. * * Format Words Description * --------------------------------------- ----- ------------------------- * 1000 zxc ccc pppppppppp 2 Branch insns * ============================================================================ */ typedef struct op_cond_br { /* Word #1 */ BFE(unsigned cond : 5, /* Condition code + x bit */ BFE(unsigned dir : 1, /* Displacement direction */ BFE(unsigned id : 4, /* Must be 1000 */ unsigned pad1 : 22))); /* Pad to 32-bit word */ /* Word #2 */ BFE(unsigned disp : 16, /* Displacement. */ unsigned pad2 : 16); /* Pad to 32-bit word */ } op_cond_br; /* * ============================================================================ * OP_DIR_2OP -- Direct->Register 2OP instructions * * Notes: * -- The 000 opcode is used by cond_br * -- The 001 opcode interprets 'dst' as a src (MVOx instruction). * * Format Words Description * --------------------------------------- ----- ------------------------- * 1ooo 000 ddd pppppppppp 2 2-op arith, direct->reg * ============================================================================ */ typedef struct op_dir_2op { /* Word #1 */ BFE(unsigned dst : 3, /* Dest. register (R0..R7) */ BFE(unsigned zero : 3, /* Must be 0 */ BFE(unsigned op : 3, /* 000 invalid */ BFE(unsigned id : 1, /* Must be 1 */ unsigned pad1 : 22)))); /* Pad to 32-bit word */ /* Word #2 */ BFE(unsigned addr : 16, /* Address (ls-bits) */ unsigned pad2 : 16); /* Pad to 32-bit word */ } op_dir_2op; /* * ============================================================================ * OP_IND_2OP -- Indirect->Register 2OP instructions * * Notes: * -- The 000 opcode is used by cond_br * -- The 001 opcode interprets 'dst' as a src (MVOx instruction). * * * Format Words Description * --------------------------------------- ----- ------------------------- * 1ooo mmm ddd 1* 2-op arith, ind. ->reg * ============================================================================ */ typedef struct op_ind_2op { BFE(unsigned reg : 3, /* Dest. register (R0..R7) */ BFE(unsigned addr : 3, /* Indirect address reg. */ BFE(unsigned op : 3, /* 000 invalid */ BFE(unsigned id : 1, /* Must be 1 */ unsigned pad1 : 22)))); /* Pad to 32-bit word */ } op_ind_2op; /* * ============================================================================ * OP_IMM_2OP -- Register->Register 2OP instructions * * Notes: * -- The 000 opcode is used by cond_br * -- The 001 opcode interprets 'dst' as a src (MVOx instruction). * * Format Words Description * --------------------------------------- ----- ------------------------- * 1ooo 111 ddd iiiiiiiiii 2* 2-op arith, immed.->reg * ============================================================================ */ typedef struct op_imm_2op { /* Word #1 */ BFE(unsigned dst : 3, /* Dest. register (R0..R7) */ BFE(unsigned one : 3, /* Must be 111 */ BFE(unsigned op : 3, /* 000 invalid */ BFE(unsigned id : 1, /* Must be 1 */ unsigned pad1 : 22)))); /* Pad to 32-bit word */ /* Word #2 */ BFE(unsigned data_lsb : 16, /* Data (ls-bits) */ unsigned pad2 : 16); /* Pad to 32-bit word */ /* Word #3 -- only when prefixed by SDBD */ BFE(unsigned data_msb : 8, /* Data (ms-bits) */ unsigned pad3 : 24); /* Pad to 32-bit word */ } op_imm_2op; /* * ============================================================================ * OP_DECODED -- General form for decoded operands * * All of the execute routines operate on the data contained in op_decoded. * Decoder functions pick apart the data in the other op_XXX types and * store it in an op_decoded structure. * * The exact meaning ascribed to the various fields is dependent on the * original opcode format as well as the instruction in question. This * format exists only because it's more convenient for the CPU to deal with * than the packed bitfields. * ============================================================================ */ typedef struct op_decoded { uint_16 imm0; /* immediate value 0 */ uint_16 imm1; /* immediate value 1 */ uint_16 reg0; /* First register */ uint_16 reg1; /* Second register */ int op; /* Actual opcode */ } op_decoded; /* * ============================================================================ * INSTR_T -- Instruction record * INSTR_FMT_T -- Enumeration of instruction formats * ============================================================================ */ typedef enum instr_fmt_t { fmt_impl_1op_a = 0, fmt_impl_1op_b = 1, fmt_jump = 2, fmt_reg_1op = 3, fmt_gswd = 4, fmt_nop_sin = 5, fmt_rot_1op = 6, fmt_reg_2op = 7, fmt_cond_br = 8, fmt_dir_2op = 9, fmt_ind_2op = 10, fmt_imm_2op = 11 } instr_fmt_t; typedef union opcode_t { unsigned encoded[3]; /* Actual raw words */ op_impl_1op_a impl_1op_a; /* Implied 1-op instruction */ op_impl_1op_b impl_1op_b; /* Implied 1-op instruction */ op_jump jump; /* Jump instruction */ op_reg_1op reg_1op; /* Register 1-op instruction */ op_gswd gswd; /* GSWD instruction */ op_nop_sin nop_sin; /* NOP or SIN instruction */ op_rot_1op rot_1op; /* Rotate/Shift instruction */ op_reg_2op reg_2op; /* Register->Register insn. */ op_cond_br cond_br; /* Conditional branch */ op_dir_2op dir_2op; /* Direct addressing insn. */ op_ind_2op ind_2op; /* Indirect addressing insn. */ op_imm_2op imm_2op; /* Immediate mode instruction */ op_decoded decoder; /* "Decoded" operation */ const op_decoded decoded; /* "Decoded" operation (const) */ } opcode_t; typedef struct instr_t { unsigned address; /* Address this insn exists at */ opcode_t opcode; } instr_t; #endif /* ======================================================================== */ /* This program is free software; you can redistribute it and/or modify */ /* it under the terms of the GNU General Public License as published by */ /* the Free Software Foundation; either version 2 of the License, or */ /* (at your option) any later version. */ /* */ /* This program is distributed in the hope that it will be useful, */ /* but WITHOUT ANY WARRANTY; without even the implied warranty of */ /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU */ /* General Public License for more details. */ /* */ /* You should have received a copy of the GNU General Public License */ /* along with this program; if not, write to the Free Software */ /* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /* ======================================================================== */ /* Copyright (c) 1998-2003, Joseph Zbiciak */ /* ======================================================================== */