Assembler + emulator for an imaginary computer
Example assembly code in /example/boot.asm
/**
* Cosmo 16-bit CPU
* General purpose registers:
* AZ, BZ, CZ, DZ, EZ, FZ, GZ, HZ
*
* Special registers:
* MO: Memory Offset
* XA: eXecution Address
* SB: Stack base
* SP: Stack ptr
*
* Flags from LSB to MSB
* ERROR
* EXCEPTION
* EQUAL
* GREATER
* LESSER
* RESET
* SHUTDOWN
*/
/**
* Instruction set:
* i-variants: takes a immediate or a label name
* b-variants: byte-wide as opposed to word-wide by default
*
* WCYL, Wait cycle does nothing
* ADD ADDi, Add, result in first operand
* AND ANDi, Logical AND, result in first operand
* CALL, Store MO, XA in stack, jumps to code offset + first operand(IMM)
* CLER, Clear error flag
* CLXP, Clear exception flag
* CMP CMPi, Sets condition flags accordingly
* DEC, Decrement inplace register
* DIV DIVi, Divide, quotient in IZ, remainder in JZ
* IN, [!] first operand(REG) is destination, second operand(IMM) is port number
* INC, Increment inplace register
* --------------------
* Following instructions jump to code offset + first operand(IMM)
* JE, Jump if equal flag set
* JER, Jump if error flag set
* JG, Jump if greater flag set
* JGE, Jump if greater flag set or equal flag set
* JL, Jump if lesser flag set
* JLE, Jump if lesser flag set or equal flag set
* JMP, Jump unconditionally
* JNE, Jump if equal flag cleared
* JNER, Jump if error flag cleared
* JNXP, Jump if exception flag cleared
* JXP, Jump if exception flag set
* LOP, Loop JZ times
* LOPE, Loop if equal
* LOPNE, Loop if not equal
* --------------------
* --------------------
* Following instructions copy the second operand to the first operand
* Move word
* MOV, register <- register
* MOVi, register <- immediate
* LOAD, register <- memory at register
* LOADi, register <- memory at immediate
* STOR, memory at register <- register
* STORi, memory at register <- immediate
* COPY, memory at register <- memory at register
* COPYi, memory at register <- memory at immediate
*
* Move byte
* LOADb, register <- memory at register
* LOADbi, register <- memory at immediate
* STORb, memory at register <- register
* STORbi, memory at register <- immediate
* COPYb, memory at register <- memory at register
* COPYbi, memory at register <- memory at immediate
* --------------------
* MUL MULi, Multiply, result in first operand
* NEG, Negate inplace
* NOT, Logical NOT inplace
* OR ORi, Logical OR, result in first operand
* OUT, [!] first operand(REG) is data, second operand(IMM) is port number
* POP, Get value from stack to first operand(REG)
* POPF, Get flags from stack
* PUSH, PUSHi, Send first operand
* PUSHF, Send flags to stack
* RET, Get ZZ, YZ from stack
* SHL, SHLi, Shift Left first operand(REG) is target, second operand(REG) is n-places
* SHR, SHRi, Shift Right first operand(REG) is target, second operand(REG) is n-places
* STER, Set error flag
* STXP, Set exception flag
* STRS, Set reset flag
* STSD, Set shutdown flag
* SUB SUBi, Substract, result in first operand
* WCYL, Wait cycle, do nothing
* XOR XORi, Logical XOR, result in first operand
*/
/**
* Memory addresses
* 0x0000 BOOT
* 0xB4FF VIDEO
*//**
* CosmoClock
* 0x31: Get year
* 0x32: Get month
* 0x33: Get day
* 0x34: Get hour
* 0x35: Get minutes
* 0x36: Get seconds
*
* CosmoScreen
* 0x44: Set video mode, 0: Text, 1: Graphics
*
* CosmoKeyboard
* 0x51: Set key selector, SDL Scancodes
* 0x52: Get selected key state, 0: Up, 1: Pressed
* 0x53: Get pressed key, SDL Scancodes
*
* CosmoDisk
* 0x61: Set mode, 0: Read, 1: Write
* 0x62: Select sector
* 0x63: Load buffer/ Write buffer
* 0x64: Get character/Put character
* 0x65: Get sector count
* 0x66: At the end of buffer
*/Used libraries: SDL2 https://www.libsdl.org/
Used font("repo:/vgafont.ttf"): PCSenior font from http://www.zone38.net/