Assembler Syntax
TODO.
Case Sensitivity
The Spin2/PASM2 syntax is completely case-insensitive. That means not only that addpix, AddPix and ADDPIX are all valid spellings of the ADDPIX instruction, but also that user defined labels and constants can be used with different casing than their definition.
For readability, documentation uses all-uppercase for any keywords, but any sane programmer uses all-lowercase in actual source files.
Operators
(TODO: Are float ops even relevant to DAT/CON?)
Unary Operators
| Operator | Term | Priority | Description |
|---|---|---|---|
| !!, NOT | !!x | 12 | Logical NOT (0 → -1, non-0 → 0) |
| ! | !x | 2 | Bitwise NOT (1's complement) |
| - | -x | 2 | Negate (2's complement) |
| -. | -.x | 2 | Floating-point negate (toggles MSB) |
| ABS | ABS x | 2 | Absolute value |
| FABS | FABS x | 2 | Floating-point absolute value (clears MSB) |
| ENCOD | ENCOD x | 2 | Encode MSB, 0..31 |
| DECOD | DECOD x | 2 | Decode, 1 << (x & $1F) |
| BMASK | BMASK x | 2 | Bitmask, (2 << (x & $1F)) - 1 |
| ONES | ONES x | 2 | Sum all '1' bits, 0..32 |
| SQRT | SQRT x | 2 | Square root of unsigned value |
| FSQRT | FSQRT x | 2 | Floating-point square root |
| QLOG | QLOG x | 2 | Unsigned value to logarithm {5'whole, 27'fraction} |
| QEXP | QEXP x | 2 | Logarithm to unsigned value |
Binary Operators
| Operator | Term | Priority | Description |
|---|---|---|---|
| >> | x >> y | 3 | Shift x right by y bits, insert 0's |
| << | x << y | 3 | Shift x left by y bits, insert 0's |
| SAR | x SAR y | 3 | Shift x right by y bits, insert MSB's |
| ROR | x ROR y | 3 | Rotate x right by y bits |
| ROL | x ROL y | 3 | Rotate x left by y bits |
| REV | x REV y | 3 | Reverse order of bits 0..y of x and zero-extend |
| ZEROX | x ZEROX y | 3 | Zero-extend above bit y |
| SIGNX | x SIGNX y | 3 | Sign-extend from bit y |
| & | x & y | 4 | Bitwise AND |
| ^ | x ^ y | 5 | Bitwise XOR |
| | | x | y | 6 | Bitwise OR |
| * | x * y | 7 | Signed multiply |
| *. | x *. y | 7 | Floating-point multiply |
| / | x / y | 7 | Signed divide, return quotient |
| /. | x /. y | 7 | Floating-point divide |
| +/ | x +/ y | 7 | Unsigned divide, return quotient |
| // | x // 7 | 7 | Signed divide, return remainder |
| +// | x +// y | 7 | Unsigned divide, return remainder |
| SCA | x SCA y | 7 | Unsigned scale, (x * y) >> 32 |
| SCAS | x SCAS y | 7 | Signed scale, (x * y) >> 30 |
| FRAC | x FRAC y | 7 | Unsigned fraction, (x << 32) / y |
| + | x + y | 8 | Add |
| +. | x +. y | 8 | Floating-point add |
| - | x - y | 8 | Subtract |
| -. | x -. y | 8 | Floating-point subtract |
| #> | x #> y | 9 | Force x => y, signed |
| <# | x <# y | 9 | Force x <= y, signed |
| ADDBITS | x ADDBITS y | 10 | Make bitfield, (x & $1F) | (y & $1F) << 5 |
| ADDPINS | x ADDPINS y | 10 | Make pinfield, (x & $3F) | (y & $1F) << 6 |
| < | x < y | 11 | Signed less than (returns 0 or -1) |
| +< | x +< y | 11 | Unsigned less than (returns 0 or -1) |
| <. | x <. y | 11 | Floating-point less than (returns 0 or -1) |
| <= | x <= y | 11 | Signed less than or equal (returns 0 or -1) |
| +<= | x +<= y | 11 | Unsigned less than or equal (returns 0 or -1) |
| <=. | x <=. y | 11 | Floating-point less than or equal (returns 0 or -1) |
| == | x == y | 11 | Equal (returns 0 or -1) |
| ==. | x ==. y | 11 | Floating-point equal (returns 0 or -1) |
| <> | x <> y | 11 | Not equal (returns 0 or -1) |
| <>. | x <>. y | 11 | Floating-point not equal (returns 0 or -1) |
| >= | x >= y | 11 | Signed greater than or equal (returns 0 or -1) |
| +>= | x +>= y | 11 | Unsigned greater than or equal (returns 0 or -1) |
| >=. | x >=. y | 11 | Floating-point greater than or equal (returns 0 or -1) |
| > | x > y | 11 | Signed greater than (returns 0 or -1) |
| +> | x +> y | 11 | Unsigned greater than (returns 0 or -1) |
| >. | x >. y | 11 | Floating-point greater than (returns 0 or -1) |
| <=> | x <=> y | 11 | Signed comparison (<,=,> returns -1,0,1) |
| &&, AND | x && y | 13 | Logical AND (x <> 0 AND y <> 0, returns 0 or -1) |
| ^^, XOR | x ^^ y | 14 | Logical XOR (x <> 0 XOR y <> 0, returns 0 or -1) |
| ||, OR | x || y | 15 | Logical OR (x <> 0 OR y <> 0, returns 0 or -1) |
Ternary Operator
| Operator | Term | Priority | Description |
|---|---|---|---|
| ? : | x ? y : z | 16 | If x <> 0 then choose y, else choose z |
Condition Codes
TODO: Maybe move this
Each instruction can have a condition code. If the condition is not met, the instruction has no effect and takes 2 cycles. (Exception: BRK and NOP may not have condition codes applied to them)
| Encoding | Primary Name | Alternate 1 | Alternate 2 | Alternate 3 | Description |
|---|---|---|---|---|---|
| %0000 | _RET_ | Always execute and return (More Info) | |||
| %0001 | IF_NC_AND_NZ | IF_NZ_AND_NC | IF_GT | IF_00 | Execute if C=0 AND Z=0 |
| %0010 | IF_NC_AND_Z | IF_Z_AND_NC | IF_01 | Execute if C=0 AND Z=1 | |
| %0011 | IF_NC | IF_GE | IF_0X | Execute if C=0 | |
| %0100 | IF_C_AND_NZ | IF_NZ_AND_C | IF_10 | Execute if C=1 AND Z=0 | |
| %0101 | IF_NZ | IF_NE | IF_X0 | Execute if Z=0 | |
| %0110 | IF_C_NE_Z | IF_Z_NE_C | Execute if C!=Z | ||
| %0111 | IF_NC_OR_NZ | IF_NZ_OR_NC | Execute if C=0 OR Z=0 | ||
| %1000 | IF_C_AND_Z | IF_Z_AND_C | IF_11 | Execute if C=1 AND Z=1 | |
| %1001 | IF_C_EQ_Z | IF_Z_EQ_C | Execute if C=Z | ||
| %1010 | IF_Z | IF_E | IF_X1 | Execute if Z=1 | |
| %1011 | IF_NC_OR_Z | IF_Z_OR_NC | Execute if C=0 OR Z=1 | ||
| %1100 | IF_C | IF_LT | IF_1X | Execute if C=1 | |
| %1101 | IF_C_OR_NZ | IF_NZ_OR_C | Execute if C=1 OR Z=0 | ||
| %1110 | IF_C_OR_Z | IF_Z_OR_C | Execute if C=1 OR Z=1 | ||
| %1111 | (empty) | IF_ALWAYS | Always execute |