Control Flow

break

--

Description

break immediately pops the lstack and moves the PC to after the loop.

Side Effects

  • lstack is popped unconditionally

return

--

Description

return returns from a subroutine call. It pops the cstack, moving the PC and DCs back to the position it was at in the caller to continue execution. This instruction returns from interrupts as well as normal subroutines, since an interrupt is a simulated subroutine call. Using return in an interrupt also allows more interrupts to be serviced unless they are explicitly disabled in the interrupt.

Side Effects

  • cstack is popped
    • PC is returned to its previous value
    • If this is the initial subroutine of an interrupt
      • It is finished servicing
      • The interrupt conveyor is replaced with the normal conveyor
      • The i bit is set

Notes

  • The lstack is NOT returned to its previous state.

Examples

calli:subr
return

:subr
  return
  • ( -- )
  • The example calls subr before returning to the original caller
jumpi:subr

subr:
  return
  • ( -- )
  • A more efficient version of the previous example by utilizing tail-call elimination

continue

--

Description

continue immediately goes to the next loop iteration and moves the PC to the beginning of the loop. If this is the last iteration it goes to the end of the loop.

Side Effects

  • Moves PC to beginning of loop normally or after the loop if this is the last iteration.

cv#

-- cv#

Description

cv# waits until the asynchronous operation that produces the value cv# completes, synchronizing with its completion, and placing the result on the stack.

Side Effects

  • Execution is synchronized with the completion of operation that produced cv#.

iloop

--

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is unsigned with a bias of +4 and is added to the PC to find the relative position of the end of the loop.

Description

iloop pushes a new infinite loop into onto the lstack. This loop, being infinite, will never end until the break instruction is issued. The loop index (i0) begins at 0 and will wrap around indefinitely.

Side Effects

Examples

iloop:+
rot0
:+
  • Enters an infinite loop with a NOP.

calli

--

Immediate (WORD)

The initial opcode byte is followed by a processor word. This word is the address of the function that is being called.

Description

calli is an immediate call. The immediate value is the address to call into.

Side Effects

  • cstack is pushed
    • Old PC is preserved.
    • Whether an interrupt is being serviced or not is preserved.

Examples

calli:subr
return

subr:
  return
  • ( -- )
  • The example calls subr before returning to the original caller

jmpi

--

Immediate (WORD)

The initial opcode byte is followed by a processor word. This word is the address to execute next.

Description

jmpi jumps to the immediate address imm.

Side Effects

  • PC is moved to immediate value.

bra

--

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bra performs a relative branch to address pc + imm.

Side Effects

  • PC is moved to pc + imm.

discard

--

Description

discard pops the lstack without going to the end like with break. This permits returning inside of a loop, but it must be called for every loop.

Side Effects

  • lstack is popped.

callri

--

Immediate (WORD)

The initial opcode byte is followed by two octets. This value is the signed offset to branch by.

Description

callri is an immediate relative call. The immediate value is the offset to branch by.

Side Effects

  • cstack is pushed
    • Old PC is preserved.
    • Whether an interrupt is being serviced or not is preserved.

Examples

callri:subr
return

subr:
  return
  • ( -- )
  • The example calls subr before returning to the original caller

call

a --

Description

call calls a subroutine. The address a is the destination the PC is set to. This pushes the cstack, storing all the state elements preserved in a call.

Side Effects

  • cstack is pushed
    • Old PC is preserved.
    • Indicates whether an interrupt is being serviced or not is preserved.

Examples

.subr call
return

subr:
  return
  • ( -- )
  • The example calls subr before returning to the original caller.

sef

a f --

Description

sef sets the fault handler for a particular fault.

Side Effects

  • Future faults of type f will immediately call a

Fault types

#NameExplanation
00Data Stack OverflowTriggers when an operation would otherwise have overflowed the dstack
01Data Stack UnderflowTriggers when an operation would otherwise have underflowed the dstack
02Signed Divide by ZeroTriggers when an operation reads a divide by zero from the conveyor
03Unsigned Divide by ZeroTriggers when an operation reads a divide by zero from the conveyor
04SegfaultTriggers when an operation attempts to read from an invalid memory address and places it on the stack

beq

a b --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

beq performs a relative branch if a == b. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if a == b.

bne

a b --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bne performs a relative branch if a != b. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if a != b.

bles

a b --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bles performs a relative branch if a < b where both operands are signed. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if a < b.

bleq

a b --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bleq performs a relative branch if a <= b where both operands are signed. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if a <= b.

blesu

a b --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

blesu performs a relative branch if a < b where both operands are unsigned. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if a < b.

blequ

a b --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

blequ performs a relative branch if a <= b where both operands are unsigned. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if a <= b.

bc

--

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bc performs a relative branch if the c bit is 1. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if c is 1.

bnc

--

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bnc performs a relative branch if the c bit is 0. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if c is 0.

bo

--

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bo performs a relative branch if the o bit is 1. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if o is 1.

bno

--

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bno performs a relative branch if the o bit is 0. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if o is 0.

bi

--

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bi performs a relative branch if the i bit is 1. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if i is 1.

bni

--

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bni performs a relative branch if the i bit is 0. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if i is 0.

jmp

a --

Description

jmp jumps to an address. The address a is the destination the PC is set to.

Examples

.subr jmp

subr:
  return
  • ( -- )
  • The example calls subr with a tail call optimization to return to the original caller.

loop

n --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is unsigned a bias of +4 and is the relative offset of the end of the loop.

Description

loop pushes a new loop into onto the lstack. n represents the number of iterations of the loop, while the immediate value imm is the unsigned relative position of the end of the loop. The loop index (i0) begins at 0.

Side Effects

reset

0 0 --

Description

Resets the whole processor, setting 0 as the new PC. Everything is reinitialized, such as stack depth. Set both parameters to 0 to ensure forwards compatibility if the parameters are altered.

bz

a --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bz performs a relative branch if a == 0. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if a == 0.

bnz

a --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bnz performs a relative branch if a != 0. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if a != 0.

ba

b --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

ba performs a relative branch if an interrupt is available on bus b. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if an interrupt is available on bus b.

bna

b --

Immediate (WORD)

The initial opcode byte is followed by two octets. The immediate value is signed and is the relative offset to branch by.

Description

bna performs a relative branch if an interrupt is not available on bus b. The pc to branch to is pc + imm.

Side Effects

  • PC is moved to pc + imm value if an interrupt is not available on bus b.