ssr.h File Reference

This file contains functions to conveniently program Snitch's SSRs. More...

Go to the source code of this file.

Enumerations
enum	snrt_ssr_dm { SNRT_SSR_DM0 = 0 , SNRT_SSR_DM1 = 1 , SNRT_SSR_DM2 = 2 , SNRT_SSR_DM_ALL = 31 }
	The different SSRs. More...
enum	snrt_ssr_dim { SNRT_SSR_1D = 0 , SNRT_SSR_2D = 1 , SNRT_SSR_3D = 2 , SNRT_SSR_4D = 3 }
	The different dimensions. More...
enum	snrt_ssr_reg {   SNRT_SSR_REG_STATUS = 0 , SNRT_SSR_REG_REPEAT = 1 , SNRT_SSR_REG_BOUNDS = 2 , SNRT_SSR_REG_STRIDES = 6 ,   SNRT_SSR_REG_IDX_CFG = 10 , SNRT_SSR_REG_IDX_BASE = 11 , SNRT_SSR_REG_RPTR_INDIR = 16 , SNRT_SSR_REG_RPTR = 24 ,   SNRT_SSR_REG_WPTR = 28 }
	The SSR configuration registers. More...
enum	snrt_ssr_idxsize { SNRT_SSR_IDXSIZE_U8 = 0 , SNRT_SSR_IDXSIZE_U16 = 1 , SNRT_SSR_IDXSIZE_U32 = 2 , SNRT_SSR_IDXSIZE_U64 = 3 }
	The size of the SSSR indirection indices. More...

Functions
void	snrt_fpu_fence ()
	Synchronize the integer and float pipelines.
void	snrt_ssr_enable ()
	Enable all SSRs.
void	snrt_ssr_disable ()
	Disable all SSRs.
void	snrt_sc_enable (uint32_t mask)
	Enable scalar chaining.
void	snrt_sc_disable (uint32_t mask)
	Disable scalar chaining.
uint32_t	read_ssr_cfg (enum snrt_ssr_reg reg, uint32_t dm)
	Read the value of an SSR configuration register.
void	write_ssr_cfg (enum snrt_ssr_reg reg, uint32_t dm, uint32_t value)
	Write a value to an SSR configuration register.
void	snrt_ssr_loop_1d (enum snrt_ssr_dm dm, size_t b0, size_t s0)
	Configure an SSR data mover for a 1D loop nest.
void	snrt_ssr_loop_2d (enum snrt_ssr_dm dm, size_t b0, size_t b1, size_t s0, size_t s1)
	Configure an SSR data mover for a 2D loop nest.
void	snrt_ssr_loop_3d (enum snrt_ssr_dm dm, size_t b0, size_t b1, size_t b2, size_t s0, size_t s1, size_t s2)
	Configure an SSR data mover for a 3D loop nest.
void	snrt_ssr_loop_4d (enum snrt_ssr_dm dm, size_t b0, size_t b1, size_t b2, size_t b3, size_t s0, size_t s1, size_t s2, size_t s3)
	Configure an SSR data mover for a 4D loop nest.
void	snrt_ssr_repeat (enum snrt_ssr_dm dm, size_t count)
	Configure the repetition count for a stream.
void	snrt_ssr_read (enum snrt_ssr_dm dm, enum snrt_ssr_dim dim, volatile void *ptr)
	Start a streaming read.
void	snrt_ssr_write (enum snrt_ssr_dm dm, enum snrt_ssr_dim dim, volatile void *ptr)
	Start a streaming write.
void	snrt_issr_set_idx_cfg (enum snrt_ssr_dm dm, enum snrt_ssr_idxsize idxsize)
	Start a streaming indirect read.
void	snrt_issr_set_bound (enum snrt_ssr_dm dm, size_t bound)
void	snrt_issr_set_ptrs (enum snrt_ssr_dm dm, volatile void *base, volatile void *idcs)
void	snrt_issr_read (enum snrt_ssr_dm dm, volatile void *base, volatile void *idcs, size_t bound, enum snrt_ssr_idxsize idxsize)

Detailed Description

This file contains functions to conveniently program Snitch's SSRs.

An SSR stream can be configured to replace a store (or load) sequence as could be generated by an N-dimensional affine loop nest, e.g. the following store sequence can be mapped to a 2D write SSR:

for (int i = 0; i < b1; i++)
    for (int j = 0; j < b0; j++)
        ptr[i * s1 + j * s0] = 0;

An ISSR (Indirect SSR) stream can be configured to replace a store (or load) sequence as could be generated by:

for (int i = 0; i < bound; i++)
    base[idcs[i]] = 0;

The convenience functions provided in this file can be used to set up such access patterns. The function argument names reflect the variable names presented in these sample code snippets.

Note: The exact number of elements configured in an (I)SSR stream must be consumed. Failure to comply with this requirement will result in undefined behaviour.

Enumeration Type Documentation

snrt_ssr_dim

enum snrt_ssr_dim

The different dimensions.

Enumerator
SNRT_SSR_1D	1D stream
SNRT_SSR_2D	2D stream
SNRT_SSR_3D	3D stream
SNRT_SSR_4D	4D stream

snrt_ssr_dm

enum snrt_ssr_dm

The different SSRs.

Enumerator
SNRT_SSR_DM0	SSR data mover 0
SNRT_SSR_DM1	SSR data mover 1
SNRT_SSR_DM2	SSR data mover 2
SNRT_SSR_DM_ALL	Write to all SSRs

snrt_ssr_idxsize

enum snrt_ssr_idxsize

The size of the SSSR indirection indices.

Enumerator
SNRT_SSR_IDXSIZE_U8	Unsigned 8-bit integer
SNRT_SSR_IDXSIZE_U16	Unsigned 16-bit integer
SNRT_SSR_IDXSIZE_U32	Unsigned 32-bit integer
SNRT_SSR_IDXSIZE_U64	Unsigned 64-bit integer

snrt_ssr_reg

enum snrt_ssr_reg

The SSR configuration registers.

Enumerator
SNRT_SSR_REG_STATUS	SSR status register
SNRT_SSR_REG_REPEAT	SSR repeat register
SNRT_SSR_REG_BOUNDS	SSR bounds register
SNRT_SSR_REG_STRIDES	SSR strides register
SNRT_SSR_REG_IDX_CFG	SSSR index configuration register
SNRT_SSR_REG_IDX_BASE	SSSR base address register
SNRT_SSR_REG_RPTR_INDIR	SSSR indir. indices read ptr register
SNRT_SSR_REG_RPTR	SSR read pointer register
SNRT_SSR_REG_WPTR	SSR write pointer register

Function Documentation

read_ssr_cfg()

uint32_t read_ssr_cfg ( enum snrt_ssr_reg reg, uint32_t dm )

inline

Read the value of an SSR configuration register.

Parameters

reg	The register index.
dm	The SSR index.

Returns

The value of the register.

snrt_issr_set_idx_cfg()

void snrt_issr_set_idx_cfg ( enum snrt_ssr_dm dm, enum snrt_ssr_idxsize idxsize )

inline

Start a streaming indirect read.

Parameters

dm	The SSSR index.
base	The base pointer to the data.
ptr	The pointer to the indirection indices.
bound	The bound of the first (and only) loop.
idxsize	The size of the indices.

snrt_sc_enable()

void snrt_sc_enable ( uint32_t mask )

inline

Enable scalar chaining.

Parameters

mask	A bitmask indicating which registers should be enabled for chaining.

snrt_ssr_loop_1d()

void snrt_ssr_loop_1d ( enum snrt_ssr_dm dm, size_t b0, size_t s0 )

inline

Configure an SSR data mover for a 1D loop nest.

Parameters

dm	The SSR index.
b0	The bound of the loop.
s0	The stride of the loop.

snrt_ssr_loop_2d()

void snrt_ssr_loop_2d ( enum snrt_ssr_dm dm, size_t b0, size_t b1, size_t s0, size_t s1 )

inline

Configure an SSR data mover for a 2D loop nest.

Parameters

dm	The SSR index.
b0	The bound of the first loop.
b1	The bound of the second loop.
s0	The stride of the first loop.
s1	The stride of the second loop.

snrt_ssr_loop_3d()

void snrt_ssr_loop_3d ( enum snrt_ssr_dm dm, size_t b0, size_t b1, size_t b2, size_t s0, size_t s1, size_t s2 )

inline

Configure an SSR data mover for a 3D loop nest.

Parameters

dm	The SSR index.
b0	The bound of the first loop.
b1	The bound of the second loop.
b2	The bound of the third loop.
s0	The stride of the first loop.
s1	The stride of the second loop.
s2	The stride of the third loop.

snrt_ssr_loop_4d()

void snrt_ssr_loop_4d ( enum snrt_ssr_dm dm, size_t b0, size_t b1, size_t b2, size_t b3, size_t s0, size_t s1, size_t s2, size_t s3 )

inline

Configure an SSR data mover for a 4D loop nest.

Parameters

dm	The SSR index.
b0	The bound of the first loop.
b1	The bound of the second loop.
b2	The bound of the third loop.
b3	The bound of the fourth loop.
s0	The stride of the first loop.
s1	The stride of the second loop.
s2	The stride of the third loop.
s3	The stride of the fourth loop.

snrt_ssr_read()

void snrt_ssr_read ( enum snrt_ssr_dm dm, enum snrt_ssr_dim dim, volatile void * ptr )

inline

Start a streaming read.

Parameters

dm	The SSR index.
dim	The number of dimensions to use.
ptr	The pointer to the data.

snrt_ssr_repeat()

void snrt_ssr_repeat ( enum snrt_ssr_dm dm, size_t count )

inline

Configure the repetition count for a stream.

Parameters

dm	The SSR index.
count	The repetition count.

snrt_ssr_write()

void snrt_ssr_write ( enum snrt_ssr_dm dm, enum snrt_ssr_dim dim, volatile void * ptr )

inline

Start a streaming write.

Parameters

dm	The SSR index.
dim	The number of dimensions to use.
ptr	The pointer to the data.

write_ssr_cfg()

void write_ssr_cfg ( enum snrt_ssr_reg reg, uint32_t dm, uint32_t value )

inline

Write a value to an SSR configuration register.

Parameters

reg	The register index.
dm	The SSR index.
value	The value to write.