Implementation

class Helper:
    def __init__(self, XLEN):
        self.XLEN = XLEN

    def EXTSXL(self, value, bits):
        bits = min(bits, self.XLEN) # strangely this is redundant
        return SelectableInt(exts(value.value, bits), self.XLEN)

Table

func	pcode
extsb	RA <- EXTSX(RS, 8)
extsh	RA <- EXTSX(RS, 16)
extsw	RA <- EXTSX(RS, 32)

Examples in tabular form

these should contain desired and expected answers, not what the code says "this is the answer if you run this code on these values". They are also CSV files which the openpower-isa unit tests can run to confirm the implementation is correct.

0xA000000090000A93

func	XLEN=64	XLEN=32	XLEN=16	XLEN=8
extsb	0xFFFFFFFFFFFFFF93	0xFFFFFF93	0xFF93	0x93
extsh	0x0000000000000A93	0x00000A93	0x0A93	0x93
extsw	0xFFFFFFFF90000A93	0x90000A93	0x0A93	0x93

Direct data download

0x0000000090000A93

func	XLEN=64	XLEN=32	XLEN=16	XLEN=8
extsb	0xFFFFFFFFFFFFFF93	0xFFFFFF93	0xFF93	0x93
extsh	0x0000000000000A93	0x00000A93	0x0A93	0x93
extsw	0xFFFFFFFF90000A93	0x90000A93	0x0A93	0x93

Direct data download

0x000000000000F074

func	XLEN=64	XLEN=32	XLEN=16	XLEN=8
extsb	0x0000000000000074	0x00000074	0x0074	0x74
extsh	0xFFFFFFFFFFFFF074	0xFFFFF074	0xF074	0x74
extsw	0x000000000000F074	0x0000F074	0xF074	0x74

Direct data download

0x0000000000000091

func	XLEN=64	XLEN=32	XLEN=16	XLEN=8
extsb	0xFFFFFFFFFFFFFF91	0xFFFFFF91	0xFF91	0x91
extsh	0x0000000000000091	0x00000091	0x0091	0x91
extsw	0x0000000000000091	0x00000091	0x0091	0x91

Direct data download

0x9999999999999999

func	XLEN=64	XLEN=32	XLEN=16	XLEN=8
extsb	0xFFFFFFFFFFFFFF99	0xFFFFFF99	0xFF99	0x99
extsh	0xFFFFFFFFFFFF9999	0xFFFF9999	0x9999	0x99
extsw	0xFFFFFFFF99999999	0x99999999	0x9999	0x99

Direct data download

0x1111111111111111

func	XLEN=64	XLEN=32	XLEN=16	XLEN=8
extsb	0x0000000000000011	0x00000011	0x0011	0x11
extsh	0x0000000000001111	0x00001111	0x1111	0x11
extsw	0x0000000011111111	0x11111111	0x1111	0x11

Direct data download

Examples

for xlen in (8, 16, 32, 64):
    helper = Helper(xlen)
    REG = lambda v: SelectableInt(v, xlen)

    assert helper.EXTSXL(REG(0xA000000090000A93), 64) == REG(0xA000000090000a93)
    assert helper.EXTSXL(REG(0x0000000090000A93), 32) == REG(0xffffffff90000a93)
    assert helper.EXTSXL(REG(0x000000000000F074), 16) == REG(0xfffffffffffff074)
    assert helper.EXTSXL(REG(0x0000000000000091),  8) == REG(0xffffffffffffff91)

    assert helper.EXTSXL(REG(0x7000000090000A93), 64) == REG(0x7000000090000a93)
    assert helper.EXTSXL(REG(0x0000000050000A93), 32) == REG(0x50000a93)
    assert helper.EXTSXL(REG(0x0000000000001074), 16) == REG(0x1074)
    assert helper.EXTSXL(REG(0x0000000000000031),  8) == REG(0x31)

    assert helper.EXTSXL(REG(0xA000000090000A93), 64) == REG(0xA000000090000a93)
    assert helper.EXTSXL(REG(0x0000000090000A93), 64) == REG(0x90000a93)
    assert helper.EXTSXL(REG(0x000000000000F074), 32) == REG(0xf074)
    assert helper.EXTSXL(REG(0x0000000000000091), 16) == REG(0x91)

    assert helper.EXTSXL(REG(0x9999999999999999), 64) == REG(0x9999999999999999)
    assert helper.EXTSXL(REG(0x9999999999999999), 32) == REG(0xFFFFFFFF99999999)
    assert helper.EXTSXL(REG(0x9999999999999999), 16) == REG(0xFFFFFFFFFFFF9999)
    assert helper.EXTSXL(REG(0x9999999999999999),  8) == REG(0xFFFFFFFFFFFFFF99)