LT4335 branch instructions

LT4335 branch instructions.
Version of 5 July 2011.
Home.

If a branch is taken, the branch-and-push instruction leaves in the stack a return address (absolute, not relative), which is the address of the first instruction in physical genspace that follows the branch instruction. The return address can also be calculated by adding 17 to the address of the branch instruction. Otherwise, the branch-and-push instruction works the same as its non-push counterpart.

At the end of a subroutine (which was presumably invoked with a branch-and-push instruction) the instruction to return is simply BA_A.

In the descriptions below:

u³ is an unsigned 3-bit integer (0…7)
u⁸ is an unsigned 8-bit integer (0…255)
s⁹ is a signed 9-bit integer (−255…+255)

u³ or u⁸ is the address of a bit within #0 to test. If it represents an unused bit, an exception will be thrown.

s⁹ is the offset, and it indicates the address, relative to that of the physically-next instruction, to which to branch. The offset is multiplied by 17 (because every instruction is 17 bits long) and added to the address of what would have been the next instruction had no branch been taken. If it is null, an exception will be thrown. If a branch relative instruction has an offset of zero, execution proceeds to the same instruction as if no branch instruction had been encountered.

Branch always. This is the venerable goto of computer programming.

BA_A branch always, absolute x⁹_100_0_0010 BPA_A branch-and-push always, absolute x⁹_100_1_0010
Pulled:
• #0 signed integer: address at which to continue execution
Pushed: none
Pulled:
• #0 signed integer: address at which to continue execution
Pushed:
• #0 signed integer: return address
BA_E branch always, relative, offset embedded s⁹_000_0_0010 BA_R branch always, relative, offset in register 0⁸1_000_0_0010
Pulled: none
Pushed: none
If s⁹ is a null integer, BA_R is performed instead.
Pulled:
• #0 signed integer: offset
Pushed: none
BPA_E branch-and-push always, relative, offset embedded s⁹_000_1_0010 BPA_R branch-and-push always, relative, offset in register 0⁸1_000_1_0010
Pulled: none
Pushed:
• #0 signed integer: return address
If s⁹ is a null integer, BPA_R is performed instead.
Pulled:
• #0 signed integer: offset
Pushed:
• #0 signed integer: return address

BA_A	branch always, absolute	x⁹_100_0_0010	BPA_A	branch-and-push always, absolute	x⁹_100_1_0010
Pulled: • #0 signed integer: address at which to continue execution Pushed: none	Pulled: • #0 signed integer: address at which to continue execution Pushed: • #0 signed integer: return address
BA_E	branch always, relative, offset embedded	s⁹_000_0_0010	BA_R	branch always, relative, offset in register	0⁸1_000_0_0010
Pulled: none Pushed: none If s⁹ is a null integer, BA_R is performed instead.	Pulled: • #0 signed integer: offset Pushed: none
BPA_E	branch-and-push always, relative, offset embedded	s⁹_000_1_0010	BPA_R	branch-and-push always, relative, offset in register	0⁸1_000_1_0010
Pulled: none Pushed: • #0 signed integer: return address If s⁹ is a null integer, BPA_R is performed instead.	Pulled: • #0 signed integer: offset Pushed: • #0 signed integer: return address

Branch string. These instructions branch according to the value of a bit, indicated by the bit number, within a string.

BS_0AE branch string on zero, absolute, bit number embedded u⁸_0001_0_0010 BS_0AR branch string on zero, absolute, bit number in register 1⁸_0001_0_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: address to which to go
Pushed: none
If u⁸ is 255, BS_0AR is performed instead.
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: address to which to go
• #2 signed integer 0…254: bit number
Pushed: none
BS_1AE branch string on one, absolute, bit number embedded u⁸_0101_0_0010 BS_1AR branch string on one, absolute, bit number in register 1⁸_0101_0_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: address to which to go
Pushed: none
If u⁸ is 255, BS_1AR is performed instead.
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: address to which to go
• #2 signed integer 0…254: bit number
Pushed: none
BS_0RB branch string on zero, relative, bit number embedded u⁸_1001_0_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: offset
If u⁸ is 255, BS_0RR is performed instead.
BS_0RO branch string on zero, relative, offset embedded s⁹_011_0_0010 BS_0RR branch string on zero, relative, all operands in registers 0⁸1_011_0_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer 0…254: bit number
If s⁹ is a null integer, BS_0RR is performed instead.
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: offset
• #2 signed integer 0…254: bit number
Pushed: none
BS_1RB branch string on one, relative, bit number embedded u⁸_1101_0_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: offset
If u⁸ is 255, BS_1RR is performed instead.
BS_1RO branch string on one, relative, offset embedded s⁹_111_0_0010 BS_1RR branch string on one, relative, all operands in registers 0⁸1_111_0_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer 0…254: bit number
If s⁹ is a null integer, BS_1RR is performed instead.
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: offset
• #2 signed integer 0…254: bit number
Pushed: none
BPS_0AE branch-and-push string on zero, absolute, bit number embedded u⁸_0001_1_0010 BPS_0AR branch-and-push string on zero, absolute, bit number in register 1⁸_0001_1_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: address to which to go
Pushed, if branch is taken:
• #0 signed integer: return address
If u⁸ is 255, BPS_0AR is performed instead.
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: address to which to go
• #2 signed integer 0…254: bit number
Pushed, if branch is taken:
• #0 signed integer: return address
BPS_1AE branch-and-push string on one, absolute, bit number embedded u⁸_0101_1_0010 BPS_1AR branch-and-push string on one, absolute, bit number in register 1⁸_0101_1_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: address to which to go
Pushed, if branch is taken:
• #0 signed integer: return address
If u⁸ is 255, BPS_1AR is performed instead.
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: address to which to go
• #2 signed integer 0…254: bit number
Pushed, if branch is taken:
• #0 signed integer: return address
BPS_0RB branch-and-push string on zero, relative, bit number embedded u⁸_1001_1_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: offset
Pushed, if branch is taken:
• #0 signed integer: return address
If u⁸ is 255, BPS_0RR is performed instead.
BPS_0RO branch-and-push string on zero, relative, offset embedded s⁹_011_1_0010 BPS_0RR branch-and-push string on zero, relative, all operands in registers 0⁸1_011_1_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer 0…254: bit number
Pushed, if branch is taken:
• #0 signed integer: return address
If s⁹ is a null integer, BPS_0RR is performed instead.
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: offset
• #2 signed integer 0…254: bit number
Pushed, if branch is taken:
• #0 signed integer: return address
BPS_1RB branch-and-push string on one, relative, bit number embedded u⁸_1101_1_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: offset
Pushed, if branch is taken:
• #0 signed integer: return address
If u⁸ is 255, BPS_1RR is performed instead.
BPS_1RO branch-and-push string on one, relative, offset embedded s⁹_111_1_0010 BPS_1RR branch-and-push string on one, relative, all operands in registers 0⁸1_111_1_0010
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer 0…254: bit number
Pushed, if branch is taken:
• #0 signed integer: return address
If s⁹ is a null integer, BPS_1RR is performed instead.
Pulled:
• #0 string: container of the bit to be tested
• #1 signed integer: offset
• #2 signed integer 0…254: bit number
Pushed, if branch is taken:
• #0 signed integer: return address

BS_0AE	branch string on zero, absolute, bit number embedded	u⁸_0001_0_0010	BS_0AR	branch string on zero, absolute, bit number in register	1⁸_0001_0_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer: address to which to go Pushed: none If u⁸ is 255, BS_0AR is performed instead.	Pulled: • #0 string: container of the bit to be tested • #1 signed integer: address to which to go • #2 signed integer 0…254: bit number Pushed: none
BS_1AE	branch string on one, absolute, bit number embedded	u⁸_0101_0_0010	BS_1AR	branch string on one, absolute, bit number in register	1⁸_0101_0_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer: address to which to go Pushed: none If u⁸ is 255, BS_1AR is performed instead.	Pulled: • #0 string: container of the bit to be tested • #1 signed integer: address to which to go • #2 signed integer 0…254: bit number Pushed: none
BS_0RB	branch string on zero, relative, bit number embedded	u⁸_1001_0_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer: offset If u⁸ is 255, BS_0RR is performed instead.
BS_0RO	branch string on zero, relative, offset embedded	s⁹_011_0_0010	BS_0RR	branch string on zero, relative, all operands in registers	0⁸1_011_0_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer 0…254: bit number If s⁹ is a null integer, BS_0RR is performed instead.	Pulled: • #0 string: container of the bit to be tested • #1 signed integer: offset • #2 signed integer 0…254: bit number Pushed: none
BS_1RB	branch string on one, relative, bit number embedded	u⁸_1101_0_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer: offset If u⁸ is 255, BS_1RR is performed instead.
BS_1RO	branch string on one, relative, offset embedded	s⁹_111_0_0010	BS_1RR	branch string on one, relative, all operands in registers	0⁸1_111_0_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer 0…254: bit number If s⁹ is a null integer, BS_1RR is performed instead.	Pulled: • #0 string: container of the bit to be tested • #1 signed integer: offset • #2 signed integer 0…254: bit number Pushed: none
BPS_0AE	branch-and-push string on zero, absolute, bit number embedded	u⁸_0001_1_0010	BPS_0AR	branch-and-push string on zero, absolute, bit number in register	1⁸_0001_1_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer: address to which to go Pushed, if branch is taken: • #0 signed integer: return address If u⁸ is 255, BPS_0AR is performed instead.	Pulled: • #0 string: container of the bit to be tested • #1 signed integer: address to which to go • #2 signed integer 0…254: bit number Pushed, if branch is taken: • #0 signed integer: return address
BPS_1AE	branch-and-push string on one, absolute, bit number embedded	u⁸_0101_1_0010	BPS_1AR	branch-and-push string on one, absolute, bit number in register	1⁸_0101_1_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer: address to which to go Pushed, if branch is taken: • #0 signed integer: return address If u⁸ is 255, BPS_1AR is performed instead.	Pulled: • #0 string: container of the bit to be tested • #1 signed integer: address to which to go • #2 signed integer 0…254: bit number Pushed, if branch is taken: • #0 signed integer: return address
BPS_0RB	branch-and-push string on zero, relative, bit number embedded	u⁸_1001_1_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer: offset Pushed, if branch is taken: • #0 signed integer: return address If u⁸ is 255, BPS_0RR is performed instead.
BPS_0RO	branch-and-push string on zero, relative, offset embedded	s⁹_011_1_0010	BPS_0RR	branch-and-push string on zero, relative, all operands in registers	0⁸1_011_1_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer 0…254: bit number Pushed, if branch is taken: • #0 signed integer: return address If s⁹ is a null integer, BPS_0RR is performed instead.	Pulled: • #0 string: container of the bit to be tested • #1 signed integer: offset • #2 signed integer 0…254: bit number Pushed, if branch is taken: • #0 signed integer: return address
BPS_1RB	branch-and-push string on one, relative, bit number embedded	u⁸_1101_1_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer: offset Pushed, if branch is taken: • #0 signed integer: return address If u⁸ is 255, BPS_1RR is performed instead.
BPS_1RO	branch-and-push string on one, relative, offset embedded	s⁹_111_1_0010	BPS_1RR	branch-and-push string on one, relative, all operands in registers	0⁸1_111_1_0010
Pulled: • #0 string: container of the bit to be tested • #1 signed integer 0…254: bit number Pushed, if branch is taken: • #0 signed integer: return address If s⁹ is a null integer, BPS_1RR is performed instead.	Pulled: • #0 string: container of the bit to be tested • #1 signed integer: offset • #2 signed integer 0…254: bit number Pushed, if branch is taken: • #0 signed integer: return address

Branch integer or float. (see also integer and float) These quick-test instructions branch according to whether an integer or float has a value, or how it compares to zero. Each instruction performs one of eight tests:

Value of u³ Branch when … Comments
0 #0 has a value, and #0 > 0 never both true
1 #0 has a value, and #0 ≤ 0
2 #0 has a value, and #0 ≠ 0 never both true
3 #0 has a value, and #0 = 0
4 #0 has a value, and #0 < 0 never both true
5 #0 has a value, and #0 ≥ 0
6 #0 is null never the same
7 #0 has a value

Value of u³	Branch when …	Comments
0	#0 has a value, and #0 > 0	never both true
1	#0 has a value, and #0 ≤ 0
2	#0 has a value, and #0 ≠ 0	never both true
3	#0 has a value, and #0 = 0
4	#0 has a value, and #0 < 0	never both true
5	#0 has a value, and #0 ≥ 0
6	#0 is null	never the same
7	#0 has a value

The tests do not attempt to handle the case where a float is to be tested with a tolerance.

BI_0A branch integer on zero, absolute u³_x⁴_000_10_0_0010 BPI0A branch-and-push integer on zero, absolute u³_x⁴_000_10_1_0010
Pulled:
• #0 signed integer: to be tested
• #1 signed integer: address to which to go
Pushed: none
Pulled:
• #0 signed integer: to be tested
• #1 signed integer: address to which to go
Pushed, if branch is taken:
• #0 signed integer: return address
BI_1A branch integer on one, absolute u³_x⁴_100_10_0_0010 BPI1A branch-and-push integer on one, absolute u³_x⁴_100_10_1_0010
Pulled:
• #0 signed integer: to be tested
• #1 signed integer: address to which to go
Pushed: none
Pulled:
• #0 signed integer: to be tested
• #1 signed integer: address to which to go
Pushed, if branch is taken:
• #0 signed integer: return address
BI_0R branch integer on zero, relative u³_x⁴_010_10_0_0010 BPI0R branch-and-push integer on zero, relative u³_x⁴_010_10_1_0010
Pulled:
• #0 signed integer: to be tested
• #1 signed integer: offset
Pushed: none
Pulled:
• #0 signed integer: to be tested
• #1 signed integer: offset
Pushed, if branch is taken:
• #0 signed integer: return address
BI_1R branch integer on one, relative u³_x⁴_110_10_0_0010 BPI1R branch-and-push integer on one, relative u³_x⁴_110_10_1_0010
Pulled:
• #0 signed integer: to be tested
• #1 signed integer: offset
Pushed: none
Pulled:
• #0 signed integer: to be tested
• #1 signed integer: offset
Pushed, if branch is taken:
• #0 signed integer: return address
BF_0A branch float on zero, absolute u³_x⁴_001_10_0_0010 BPF_0A branch-and-push float on zero, absolute u³_x⁴_001_10_1_0010
Pulled:
• #0 float: to be tested
• #1 signed integer: address to which to go
Pushed: none
Pulled:
• #0 float: to be tested
• #1 signed integer: address to which to go
Pushed, if branch is taken:
• #0 signed integer: return address
BF_1A branch float on one, absolute u³_x⁴_101_10_0_0010 BPF_1A branch-and-push float on one, absolute u³_x⁴_101_10_1_0010
Pulled:
• #0 float: to be tested
• #1 signed integer: address to which to go
Pushed: none
Pulled:
• #0 float: to be tested
• #1 signed integer: address to which to go
Pushed, if branch is taken:
• #0 signed integer: return address
BF_0R branch float on zero, relative u³_x⁴_011_10_0_0010 BPF_0R branch-and-push float on zero, relative u³_x⁴_011_10_1_0010
Pulled:
• #0 float: to be tested
• #1 signed integer: offset
Pushed: none
Pulled:
• #0 float: to be tested
• #1 signed integer: offset
Pushed, if branch is taken:
• #0 signed integer: return address
BF_1R branch float on one, relative u³_x⁴_111_10_0_0010 BPF_1R branch-and-push float on one, relative u³_x⁴_111_10_1_0010
Pulled:
• #0 float: to be tested
• #1 signed integer: offset
Pushed: none
Pulled:
• #0 float: to be tested
• #1 signed integer: offset
Pushed, if branch is taken:
• #0 signed integer: return address

BI_0A	branch integer on zero, absolute	u³_x⁴_000_10_0_0010	BPI0A	branch-and-push integer on zero, absolute	u³_x⁴_000_10_1_0010
Pulled: • #0 signed integer: to be tested • #1 signed integer: address to which to go Pushed: none	Pulled: • #0 signed integer: to be tested • #1 signed integer: address to which to go Pushed, if branch is taken: • #0 signed integer: return address
BI_1A	branch integer on one, absolute	u³_x⁴_100_10_0_0010	BPI1A	branch-and-push integer on one, absolute	u³_x⁴_100_10_1_0010
Pulled: • #0 signed integer: to be tested • #1 signed integer: address to which to go Pushed: none	Pulled: • #0 signed integer: to be tested • #1 signed integer: address to which to go Pushed, if branch is taken: • #0 signed integer: return address
BI_0R	branch integer on zero, relative	u³_x⁴_010_10_0_0010	BPI0R	branch-and-push integer on zero, relative	u³_x⁴_010_10_1_0010
Pulled: • #0 signed integer: to be tested • #1 signed integer: offset Pushed: none	Pulled: • #0 signed integer: to be tested • #1 signed integer: offset Pushed, if branch is taken: • #0 signed integer: return address
BI_1R	branch integer on one, relative	u³_x⁴_110_10_0_0010	BPI1R	branch-and-push integer on one, relative	u³_x⁴_110_10_1_0010
Pulled: • #0 signed integer: to be tested • #1 signed integer: offset Pushed: none	Pulled: • #0 signed integer: to be tested • #1 signed integer: offset Pushed, if branch is taken: • #0 signed integer: return address
BF_0A	branch float on zero, absolute	u³_x⁴_001_10_0_0010	BPF_0A	branch-and-push float on zero, absolute	u³_x⁴_001_10_1_0010
Pulled: • #0 float: to be tested • #1 signed integer: address to which to go Pushed: none	Pulled: • #0 float: to be tested • #1 signed integer: address to which to go Pushed, if branch is taken: • #0 signed integer: return address
BF_1A	branch float on one, absolute	u³_x⁴_101_10_0_0010	BPF_1A	branch-and-push float on one, absolute	u³_x⁴_101_10_1_0010
Pulled: • #0 float: to be tested • #1 signed integer: address to which to go Pushed: none	Pulled: • #0 float: to be tested • #1 signed integer: address to which to go Pushed, if branch is taken: • #0 signed integer: return address
BF_0R	branch float on zero, relative	u³_x⁴_011_10_0_0010	BPF_0R	branch-and-push float on zero, relative	u³_x⁴_011_10_1_0010
Pulled: • #0 float: to be tested • #1 signed integer: offset Pushed: none	Pulled: • #0 float: to be tested • #1 signed integer: offset Pushed, if branch is taken: • #0 signed integer: return address
BF_1R	branch float on one, relative	u³_x⁴_111_10_0_0010	BPF_1R	branch-and-push float on one, relative	u³_x⁴_111_10_1_0010
Pulled: • #0 float: to be tested • #1 signed integer: offset Pushed: none	Pulled: • #0 float: to be tested • #1 signed integer: offset Pushed, if branch is taken: • #0 signed integer: return address

Branch uninterruptable. These tests inquire of the the CPU whether it is willing to perform the the next several instructions atomically, that is to say suppressing any interrupts, context switches, et cetera.

If the CPU is willing, the branch is taken on a grant, and skipped on a deny.
If the CPU is unwilling, the branch is taken on a deny and skipped on a grant.

The branch uninterruptable instruction itself does not count toward the instruction count.

The purpose of the branch uninterruptable tests is to allow short instruction sequences to be processed atomically, while still preventing any one thread from taking over the machine. Some CPUs might be wired with a fixed maximum count, while others might fluctuate according to the circumstances.

A request of zero instructions, being trivially satisfiable, is always granted.
A request of one instruction is always granted, because any single instruction is uninterruptable whether requested or not.
A request that is negative throws an exception.
A request that is a null integer is denied.

Programmers frequently need (for instance, for semaphores) an uninterruptable sequence similar to this: (1) read an integer from genspace into a register, (2) increment the integer, and (3) write the integer from the register into genspace. Thus for programs to make good progress, three-instruction requests should rarely be denied. To go further: if the designers of a particular implementation of the CPU see that it will always be sensible to grant uninterruptibility for short sequences, they can include a simpler instruction (see XU_DE and XU_DR below) that omits branching information.

A program, having been granted one uninterruptability request, might ask for a second before the first expires:

If the second request would expire no later than the first, it will be granted.
If the second request would expire later than the first, and it is denied, the first request continues normally.
If the second request would expire later than the first, and it is granted, then the second will start to run immediately, and the remainder of the first request will be forgotten. In this case, there will be no break in uninterruptability as the first request ends and the second begins.

The use of branching means that a clever program, when faced with a denied request, can try an alternate means to accomplish the task at hand, or can initiate a non-busy wait.

Ideally, there will be no constraint on what kinds of instructions may be executed during the uninterruptable period. Whether this can be accomplished in practice is an open issue, raising the question of what to do if uninterruptibility is granted, and then an ineligible instruction is encountered.

Throwing an exception in the midst of an unterruptable section is no panacea, because it may leave inconsistent data in shared genspace, confusing other CPUs in a multiprocessor system.

A complication is that an uninterruptable segment might contain ordinary conditional branching statements, and it would be difficult for the CPU to pre-scan all possible paths within the program in order to verify that all instructions qualify. Even a total prohibition of branching statements, which might make a pre-scan feasible in a pipelining environment, still leaves a problem if some instruction throws an exception that the programmer did not anticipate, such as a get from a bad address.

BU_DAE branch uninterruptable deny, absolute, instruction count embedded u⁸_0001_0_1010 BU_DAR branch uninterruptable deny, absolute, instruction count in register 0⁸_0001_0_1010
Pulled:
• #0 signed integer: address to which to go
Pushed: none
If u⁸ is 0, BU_DAR is performed instead.
Pulled:
• #0 signed integer: address to which to go
• #1 signed integer 0…255: instruction count
Pushed: none
BU_GAE branch uninterruptable grant, absolute, instruction count embedded u⁸_0101_0_1010 BU_GAR branch uninterruptable grant, absolute, instruction count in register 0⁸_0101_0_1010
Pulled:
• #0 signed integer: address to which to go
Pushed: none
If u⁸ is 0, BU_GAR is performed instead.
Pulled:
• #0 signed integer: address to which to go
• #1 signed integer 0…255: instruction count
Pushed: none
BU_DRI branch uninterruptable deny, relative, instruction count embedded u⁸_1001_0_1010
Pulled:
• #0 signed integer: offset
If u⁸ is 0, BU_DRR is performed instead.
BU_DRO branch uninterruptable deny, relative, offset embedded s⁹_011_0_1010 BU_DRR branch uninterruptable deny, relative, all operands in registers 0⁸1_011_0_1010
Pulled:
• #0 signed integer 0…255: instruction count
If s⁹ is a null integer, BU_DRR is performed instead.
Pulled:
• #0 signed integer: offset
• #1 signed integer 0…255: instruction count
Pushed: none
BU_GRI branch uninterruptable grant, relative, instruction count embedded u⁸_1101_0_1010
Pulled:
• #0 signed integer: offset
If u⁸ is 0, BU_GRR is performed instead.
BU_GRO branch uninterruptable grant, relative, offset embedded s⁹_111_0_1010 BU_GRR branch uninterruptable grant, relative, all operands in registers 0⁸1_111_0_1010
Pulled:
• #0 signed integer 0…255: instruction count
If s⁹ is a null integer, BU_GRR is performed instead.
Pulled:
• #0 signed integer: offset
• #1 signed integer 0…255: instruction count
Pushed: none
BPU_DAE branch-and-push uninterruptable deny, absolute, instruction count embedded u⁸_0001_1_1010 BPU_DAR branch-and-push uninterruptable deny, absolute, instruction count in register 0⁸_0001_1_1010
Pulled:
• #0 signed integer: address to which to go
Pushed, if branch is taken:
• #0 signed integer: return address
If u⁸ is 0, BPU_DAR is performed instead.
Pulled:
• #0 signed integer: address to which to go
• #1 signed integer 0…255: instruction count
Pushed, if branch is taken:
• #0 signed integer: return address
BPU_GAE branch-and-push uninterruptable grant, absolute, instruction count embedded u⁸_0101_1_1010 BPU_GAR branch-and-push uninterruptable grant, absolute, instruction count in register 0⁸_0101_1_1010
Pulled:
• #0 signed integer: address to which to go
Pushed, if branch is taken:
• #0 signed integer: return address
If u⁸ is 0, BPU_GAR is performed instead.
Pulled:
• #0 signed integer: address to which to go
• #1 signed integer 0…255: instruction count
Pushed, if branch is taken:
• #0 signed integer: return address
BPU_DRI branch-and-push uninterruptable deny, relative, instruction count embedded u⁸_1001_1_1010
Pulled:
• #0 signed integer: offset
Pushed, if branch is taken:
• #0 signed integer: return address
If u⁸ is 0, BPU_DRR is performed instead.
BPU_DRO branch-and-push uninterruptable deny, relative, offset embedded s⁹_011_1_1010 BPU_DRR branch-and-push uninterruptable deny, relative, all operands in registers 0⁸1_011_1_1010
Pulled:
• #0 signed integer 0…255: instruction count
Pushed, if branch is taken:
• #0 signed integer: return address
If s⁹ is a null integer, BPU_DRR is performed instead.
Pulled:
• #0 signed integer: offset
• #1 signed integer 0…255: instruction count
Pushed, if branch is taken:
• #0 signed integer: return address
BPU_GRI branch-and-push uninterruptable grant, relative, instruction count embedded u⁸_1101_1_1010
Pulled:
• #0 signed integer: offset
Pushed, if branch is taken:
• #0 signed integer: return address
If u⁸ is 0, BPU_GRR is performed instead.
BPU_GRO branch-and-push uninterruptable grant, relative, offset embedded s⁹_111_1_1010 BPU_GRR branch-and-push uninterruptable grant, relative, all operands in registers 0⁸1_111_1_1010
Pulled:
• #0 signed integer 0…255: instruction count
Pushed, if branch is taken:
• #0 signed integer: return address
If s⁹ is a null integer, BPU_GRR is performed instead.
Pulled:
• #0 signed integer: offset
• #1 signed integer 0…255: instruction count
Pushed, if branch is taken:
• #0 signed integer: return address

BU_DAE	branch uninterruptable deny, absolute, instruction count embedded	u⁸_0001_0_1010	BU_DAR	branch uninterruptable deny, absolute, instruction count in register	0⁸_0001_0_1010
Pulled: • #0 signed integer: address to which to go Pushed: none If u⁸ is 0, BU_DAR is performed instead.	Pulled: • #0 signed integer: address to which to go • #1 signed integer 0…255: instruction count Pushed: none
BU_GAE	branch uninterruptable grant, absolute, instruction count embedded	u⁸_0101_0_1010	BU_GAR	branch uninterruptable grant, absolute, instruction count in register	0⁸_0101_0_1010
Pulled: • #0 signed integer: address to which to go Pushed: none If u⁸ is 0, BU_GAR is performed instead.	Pulled: • #0 signed integer: address to which to go • #1 signed integer 0…255: instruction count Pushed: none
BU_DRI	branch uninterruptable deny, relative, instruction count embedded	u⁸_1001_0_1010
Pulled: • #0 signed integer: offset If u⁸ is 0, BU_DRR is performed instead.
BU_DRO	branch uninterruptable deny, relative, offset embedded	s⁹_011_0_1010	BU_DRR	branch uninterruptable deny, relative, all operands in registers	0⁸1_011_0_1010
Pulled: • #0 signed integer 0…255: instruction count If s⁹ is a null integer, BU_DRR is performed instead.	Pulled: • #0 signed integer: offset • #1 signed integer 0…255: instruction count Pushed: none
BU_GRI	branch uninterruptable grant, relative, instruction count embedded	u⁸_1101_0_1010
Pulled: • #0 signed integer: offset If u⁸ is 0, BU_GRR is performed instead.
BU_GRO	branch uninterruptable grant, relative, offset embedded	s⁹_111_0_1010	BU_GRR	branch uninterruptable grant, relative, all operands in registers	0⁸1_111_0_1010
Pulled: • #0 signed integer 0…255: instruction count If s⁹ is a null integer, BU_GRR is performed instead.	Pulled: • #0 signed integer: offset • #1 signed integer 0…255: instruction count Pushed: none
BPU_DAE	branch-and-push uninterruptable deny, absolute, instruction count embedded	u⁸_0001_1_1010	BPU_DAR	branch-and-push uninterruptable deny, absolute, instruction count in register	0⁸_0001_1_1010
Pulled: • #0 signed integer: address to which to go Pushed, if branch is taken: • #0 signed integer: return address If u⁸ is 0, BPU_DAR is performed instead.	Pulled: • #0 signed integer: address to which to go • #1 signed integer 0…255: instruction count Pushed, if branch is taken: • #0 signed integer: return address
BPU_GAE	branch-and-push uninterruptable grant, absolute, instruction count embedded	u⁸_0101_1_1010	BPU_GAR	branch-and-push uninterruptable grant, absolute, instruction count in register	0⁸_0101_1_1010
Pulled: • #0 signed integer: address to which to go Pushed, if branch is taken: • #0 signed integer: return address If u⁸ is 0, BPU_GAR is performed instead.	Pulled: • #0 signed integer: address to which to go • #1 signed integer 0…255: instruction count Pushed, if branch is taken: • #0 signed integer: return address
BPU_DRI	branch-and-push uninterruptable deny, relative, instruction count embedded	u⁸_1001_1_1010
Pulled: • #0 signed integer: offset Pushed, if branch is taken: • #0 signed integer: return address If u⁸ is 0, BPU_DRR is performed instead.
BPU_DRO	branch-and-push uninterruptable deny, relative, offset embedded	s⁹_011_1_1010	BPU_DRR	branch-and-push uninterruptable deny, relative, all operands in registers	0⁸1_011_1_1010
Pulled: • #0 signed integer 0…255: instruction count Pushed, if branch is taken: • #0 signed integer: return address If s⁹ is a null integer, BPU_DRR is performed instead.	Pulled: • #0 signed integer: offset • #1 signed integer 0…255: instruction count Pushed, if branch is taken: • #0 signed integer: return address
BPU_GRI	branch-and-push uninterruptable grant, relative, instruction count embedded	u⁸_1101_1_1010
Pulled: • #0 signed integer: offset Pushed, if branch is taken: • #0 signed integer: return address If u⁸ is 0, BPU_GRR is performed instead.
BPU_GRO	branch-and-push uninterruptable grant, relative, offset embedded	s⁹_111_1_1010	BPU_GRR	branch-and-push uninterruptable grant, relative, all operands in registers	0⁸1_111_1_1010
Pulled: • #0 signed integer 0…255: instruction count Pushed, if branch is taken: • #0 signed integer: return address If s⁹ is a null integer, BPU_GRR is performed instead.	Pulled: • #0 signed integer: offset • #1 signed integer 0…255: instruction count Pushed, if branch is taken: • #0 signed integer: return address

The next instructions are suitable if the programmer is confident that the request for uninterruptability will be granted.

XU_DE exception if uninterruptable denied, instruction count embedded 0⁸_ XU_DR exception if uninterruptable denied, instruction count in register 0⁸_
Pulled: none
Pushed: none
If u⁸ is 0, XU_DR is performed instead.
Pulled:
• #0 signed integer 0…255: instruction count
Pushed: none