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5 - Mathematics
The math instructions generally work off of the t register in conjunction with another register. This register can be selected either via the RPTR index, or directly.| add rp; add pc; add sp | addc rp | addx4 rp | dec rp; dec t |
| Addition of the t register and the current register via the RPTR index, the program counter, or the stack pointer, respectively. | Same as 'add rp', but with the carry flag included. | Addition to t of a register value. The 'x4' indicates the value is shifted before addition, effectively adding the value four times. | Decrement the register pointed to by RPTR (or the t register) by one. |
| dec2 rp; dec2 t | inc rp; inc t | inc2 rp; inc2 t | inc4 rp; inc4 t |
| Decrement the register pointed to by RPTR or the t register by two. | Increment the register pointed to by RPTR or the t register by one. | Increment the register pointed to by RPTR or the t register by two. | Increment the register pointed to by RPTR or the t register by four. |
| neg rp; neg t | sub rp | subc rp | subcr rp |
| Negate (two's complement) the value in the specified register or the t register. | Subtract selected register's value from the t register, placing result in t afterwards. | Subtract selected register's value from the t register with carry. | Subtract t from the selected register's value with carry, placing the result into t. |
| subr rp | sx8 rp | sx16 rp | zsub rp |
| Subtract t from the selected register without carry. | Sign extend the specified register's 8 bits to 32 bits. | Sign extend specified register's 16 bits to 32 bits. | Subtract contents of specifed register from zero, placing in t. |
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